phew.... had another *almost* disaster this weekend. i was in heavy traffic trying to get to the stadium and was merging over a lane, right on top of those steel "zipper" looking things that join sections of overpasses together. hit the bump, brakes went TO THE FLOOR, wife screamed :eek:, almost slammed into a BMW X5 that was stopped in the right lane.

DAMN, something has GOT to be done about this.... at this point tho', what can Subaru do? nothing!! :mad: its not like they can change a part to correct this, they are F#CKED UP! am i to assume the entire '02 lineup has these problems? or is this an Impreza problem? im worried for winter :( :confused:

Bob

I believe this is a common problem in all 2002 WRXs.

Interestingly, someone posted an opposing view: http://www.i-club.com/forums/showthread.php?s=&threadid=102889

Not that I'm about to disconnect my ABS.

I wonder what breaking will be like this winter in New England?

Cheers!
David

It happens to the 02 RS too. :(

Have your car checked out by competent independent shop, since nobody here trusts Subaru to do anything but sit and smile. Then after they fix it, send the fix to SOA for their amusement, and call the NHTSA Auto Safety Hotline (toll free at 1-888-DASH-2-DOT) to report safety defects or to obtain information on cars, trucks, child seats, highway or traffic safety.
But remember it took them 15 years to catch up to Ford and Firestone, so please be patient.

There is simply no way I'm giong to buy a WRX untill this issue gets resolved. :(

Originally posted by westy66
phew.... had another *almost* disaster this weekend. i was in heavy traffic trying to get to the stadium and was merging over a lane, right on top of those steel "zipper" looking things that join sections of overpasses together. hit the bump, brakes went TO THE FLOOR, wife screamed :eek:, almost slammed into a BMW X5 that was stopped in the right lane.

DAMN, something has GOT to be done about this.... at this point tho', what can Subaru do? nothing!! :mad: its not like they can change a part to correct this, they are F#CKED UP! am i to assume the entire '02 lineup has these problems? or is this an Impreza problem? im worried for winter :( :confused:

Bob

This isn't a Subaru poblem, but a typical 'con' with ABS. Everything is a trade-off. ABS can be fooled by bumps on the road, railroad tracks, snow,etc. The most common examble is that of trying to stop in heavy snow. ABS makes it worse, since it does not allow the tire to 'dig in'. This has been an OLD OLD issue since ABS first came out with ANY car.

The good news is your ABS in the Subaru is top notch and as most modern cars has 4 sensors.. each tire works independently... so the effect is minimized as much as is possible.

Don't like it? Pull the fuse and practice manual panic bracking. Personally, I prefer ABS. I believe its pros outweight the cons. I got a couple flat spotted front tires on my Miata once that really brought the point home ($$).

Rick

Originally posted by Flashman
This isn't a Subaru poblem, but a typical 'con' with ABS. Everything is a trade-off. ABS can be fooled by bumps on the road, railroad tracks, snow,etc.

Rick

i dont know.... ive driven a lot of different cars with ABS and havnt noticed ANYTHING like this before.

The brake pedal really went to the floor? At the point where the resistance in the pedal left were you still getting baking power at all or was the car free to coast? I really don't think that you can say that the pedal dropping from under your foot is "normal".

Ive had the exactly same thing happen to me twice coming into a tollbooth over bumpy pavement. ABS decided tires were slipping, and hence, no brakes. Scared the @#$$ out of me.

No, it really does go way down, almost to the floor. Braking power appears to disappear completely. I experienced this on a test drive when I was braking for a stoplight from 40mph and crossed a section of rippled pavement. Thank god I didn't have anyone in front of me because even with panic braking (foot HARD to the floor) it took me 3-4 times the normal distance to stop the car. I started braking WAY early because I was testing out how smooth I could get the car to downshift, and I still almost rolled into the intersection.

This is a very real problem that both SOA and numerous posters on the I-club are trying to discount. The WRX is a great car, but this braking problem is a serious issue. I wonder how many of the NUMEROUS wrecks that have occurred recently could have been avoided had the car's braking system been working properly. In my opinion, this is more serious than the infamous Audi "unintended acceleration" problem of the 1980s, only in this case the problem is real and not a hoax invented by a television show.

Evidently Subaru thinks that the press would be so bad from this that they choose to ignore the problem, hoping that they can make it through this model year without major drama until they can fix the problem in the next revision of the ABS system.

:mad:

I get behavior similar to this on my MY00 RS (thought not as bad from the sound of it), so it's not limited to the newer Imprezas. There were some bumps in the pavement at the joints on a bridge on my way to work, just before the parking lot turn in. If i was braking hard when i went over them, the ABS would kick in, and refused to let me slow down. Very disconcerting.

If you have the brakes on, and the tire bounces up off the pavement, the tire stops. ABS sees that as a locked wheel, and triggers. I always wondered if having nicer shocks would help this (thinking they could help keep the tire in better contact with the road), but i lost my job before i installed the new AGX's. =\

OK this is a long one....

braking (foot HARD to the floor) it took me 3-4 times the normal distance to stop the car.

When you hit the brakes, do you just leave your foot on the brake?

If you hit a (one) bump at the time you engage your brakes hard, the ABS will go on and STAY on until you lift off the brake.

Yes, it will take about 3-4 times the distance to stop because the ABS was designed for you maneuver AROUND an obsticle in your way without locking. Turning locked front wheels causes severe understeer and you'd plow into the subject you were trying to avoid.. hard.

Learning proper braking in any given situation is very important. 1st rule is STAY CALM. Let your brain control your foot and not your reactions to the events... adrenaline. (or your wife/passenger screaming or gasping for that matter).

If you feel your ABS come on, yet there's no continuous bumps, (ie you hit one bump that forced them to activate) ease off a little and re-apply the brakes. It only takes a fraction of a second to do this. But, make sure you are going in almost a straight line. If you do this at speed around a corner, you WILL get lift throttle oversteer.

Practice this in a parking lot that has bumps, or near street that has bumpy pavement or potholes. Here in the North East, we have plenty. Just make SURE there's no one else in front or around you when you do this. Be in a rural area, out of residential neighborhoods. (Train tracks in the middle of nowhere helps.) Just practice will get you the better feel for things. (We auto-x on some bumpy courses, and I've gotten familiar with the subaru ABS system over bumps... my RS used to do this too...I do feel that Subaru makes one of the best ABS systems out there).

If you get stopped by those in blue, explain the situation witha cevat like, "i'd rateher learn the limits of my braking and what happens with ABS in a safe envronment where there's no danger of hitting anyone instead of getting in an accident." Usually they either say, ok, or just take it somewhere else. If you're alone in a non-0residential area and there's no-one around, it'd be hard to get a ticket for learniong to be a better driver. :)

It takes practice, reptitiveness and patience. But learning where ABS Kicks in and what to to braking wise, can mean the difference between a non-accident, a fender bender or a totalled car.

--kC

Thanks for the great explanation KC, but what you're describing is a normal ABS system in operation. This is exactly the kind of BS response that everybody who's experienced this problem has been getting. This is NOT a normal ABS system in operation. No other car with ABS has acted this way, and I've driven LOTS of them.

Once I realized the pedal had gone to the floor, I completely removed my foot from the pedal, then tried to reapply braking pressure.... there was NOTHING. No pedal resistance whatsoever.

By the way, your statement about ABS being designed to make braking distances 3-4 times longer is TOTAL BS. The whole point of AntiLock brakes is to reduce braking distance by preventing wheel lock. A rolling wheel stops sooner than a sliding wheel.... remember? The ability to steer around an obstacle is merely a convenient bonus.

I ESPECIALLY resent your implication that everyone who has this problem simply doesn't know how to drive. That seems to have been the #1 response on this board, and it comes from people who really DON'T KNOW WHAT THEY"RE TALKING ABOUT because they haven't experienced the phenomenon firsthand.

Trust me, I can drive quite well, and I can brake with ABS quite effectively. Believe me, I've explored the limits of ABS on too many cars to mention right now, most of them rentals. :devil: This behavior is in NO WAY normal.

:monkey:

Originally posted by Porter
...Once I realized the pedal had gone to the floor, I completely removed my foot from the pedal, then tried to reapply braking pressure.... there was NOTHING. No pedal resistance whatsoever...

Is this phenomenon reproducible? Can you make it happen given the correct (or incorrect) environment and driver input? There seems to be a common thread to the posts on this subject. Most are mentioning an expansion joint or flex joint on a bridge as being a key ingrediant.

It is obviously not normal and needs to be brought to Subaru's attention. The only way to get over the hurdle of getting people to believe that it isn't driver error is to demonstrate the failure to them. I suppose there is another way to get them to admit that there is a problem but that involves many Subaru accidents and subsequent insurance claims. The latter isn't the method of choice.

So far I have only experienced the ABS engaging when I didn't think it should have. I was braking and starting a turn at about 15-20MPH over a bumpy area. The pedal didn't go to the floor but the ABS activated and it gave the impression of extending my stopping distance. I believe I could have pressed harder on the pedal and brought the car to a stop faster but I didn't need to. This cannot be what you are experiencing. If the pedal drops it is not driver error. Let's get past that.

My question, if you missed it is, can you make it happen again (and again), given the correct environment? This would make it much easier to address.

It seems as if some can reproduce the problem. If so, have they been able to get a Subaru tech to experience the problem? What was the result?

Here's a link to a somewhat dated site that contains quite a bit of ranting about similar problems:
http://home.sprynet.com/~mklphoto/SUBARU1.HTM

It's amazing how many people recently woke up on the wrong side of the bed. Chill dude. :) Let me explain what I said in a better way, using my and your comments.

I'm not the best writer in the world. I'll admit that whole hartedly. I never really cite reference becuase no matter what, someone else has other reference to refute a claim. So I can only respond to certain comments brought up. I'm not saying YOU HAVE TO do this or else. There are just suggestions that I put above and you can ignore them or try them out. :) It's up to you. Also, sometimes things are left out of the original story to make a point, or just throught they were so insignificant, they didn't matter. ("It's all in the detials") ;)

Yes, it will take about 3-4 times the distance to stop because the ABS was designed for you maneuver AROUND

It's not 3-4 times. I was using what you said as a quick reference. After re-reading it, I'll change that to... ABS, on dry pavement, does NOTHING to SHORTEN your stopping distances compared to a like system without ABS using threshold braking. (Threshold braking...braking to the point just before the wheels lock up). ABS releases the brakes and then engages, then releases, then engages, ohhh about 100 times a second. That's what they do. Threshold braking and braking uner normal circumstances on flat, level dry road, going straight, will ALWAYS stop better than ABS in the same car.

A rolling wheel stops sooner than a sliding wheel.... remember? The ability to steer around an obstacle is merely a convenient bonus.

See my 1st post. In simple terms: Sliding=bad (understeer in my post was meant as sliding, locked tires... you have no manueverability) ABS=Good to move and stop better. Threshold braking=best. It also depends on vehicle speed.

Me: I ESPECIALLY resent your implication that everyone who has this problem simply doesn't know how to drive. That seems to have been the #1 response on this board, and it comes from people who really DON'T KNOW WHAT THEY"RE TALKING ABOUT because they haven't experienced the phenomenon firsthand.

You: Once I realized the pedal had gone to the floor, I completely removed my foot from the pedal, then tried to reapply braking pressure.... there was NOTHING. No pedal resistance whatsoever.

Why did you take offense at a suggestion? That's all it was. You in fact did what I said... remove foot from ABS and re-apply. So you agree with me. What happened next was not normal. And wasn't said in the orginal post. But you resent the fact that I suggested you do something you already do? I don't get it. :)

Lastly, you read too much into what I said. That's the problem with the written word instead of face to face communication. You can get too many interpretations.

I experienced this on a test drive when I was braking for a stoplight from 40mph and crossed a section of rippled pavement. I started braking WAY early because I was testing out how smooth I could get the car to downshift, and I still almost rolled into the intersection.

So you were concentrating on your downshifting rather than braking, in a car you were testdriving? Was it your car then, or were you looking at purchasing a car? Friends car? See the problem with the written word? :)

You may indeed have a problem with your car. I never said that in my post because just as "get it checked out, you may have a problem" is a suggestion, "learn threshold braking" is another.

I'm on your side. If you think it's a problem have it looked at. But most of the other symptoms listed in this post by others here ARE NORMAL in a Subaru. The issue I would have (with your car) with the dealer is that when you lifted and then re-applied, there was NO braking pressure. That's a problem. ABS going on, under hard braking over bumps, is normal. Having no braking at all afterwards is not.

Nebver at any time. I never questioned your ability to drive.

I mean you no harm. Take me to your leader. :alien: :)

--kC

Sorry KC, I didn't mean to jump all over you like that.

The reason I'm a little touchy about this is that many people in other threads dedicated to the subject have reported exactly the same phenomenon.... TOTAL loss of braking when attempting to brake on an uneven surface. Not one wheel, but all four calipers completely ceasing to clamp.

I'll go back and find the other threads so I can show the pattern a little more clearly, i.e. owner reports problem with the braking system letting go on him, and several other I-clubbers jumping on him and telling him that it's perfectly normal ABS operation and that he simply doesn't know how to drive with ABS.

Please don't take my comments personally, I was just expressing frustration. I personally prefer to threshold brake, I learned to drive in a non-ABS vehicle and learned how to make it handle in all kinds of weather and surface conditions.

BTW, this happened on a test drive from the dealer, the salesman sitting next to me almost had a heart attack... he was like "Um, I'd better get that checked out when we get back." He told me later that he'd had another customer who had brought their car in several times for this problem and they'd been unable to fix it.

BTW this was a dealer in Virginia.

I'll dig up those old threads, see ya in a minute....

[edit] hmmm.... the search function seems to have crapped itself.

My dad had a '97 dodge ram with 4 wheel abs. I used to drive it up and down my street in the winter time and intentionally slam on the brakes. The brake pedal fell totally to the floor pan and then kicked back up at me and then sunk once more and stayed there while the brakes were doing their thing. My mom's Honda CR-V does this although not as hard as the truck, my 2.5RS does this although less than either of them. Thus far it feels the best. I've driven a new generation Dodge Neon with abs and it feels like somewhere in the middle of the ram and the CR-V,

So, wow, I had been reading about all of these breaking problems and had never really experienced it until the other day. I just started college and moved into an apartment complex, and right after the entrance (a couple hundred feet) there's a crack type dealey :) in the ground, then a speed bump. So after turning into the place, I'm going about 10~15 mph, and slowly start applying the breaks for the speed bump (they're huge) and right then and there, EVERY TIME, my abs triggers, and the pedal drops to the floor. Keep in mind, this is under light breaking.

Since I'm not familiar with the area enough, I can't bring my car in and say try to fix it right now. And yes, you're probably thinking, oh it's a young guy, he doesn' t know how to drive. Well, I would think I have some experience driving, I went to Bondurant, and i've driven a few high performance (camaro ss, viper) and well built (bmw 330, toyota sequoia) and my old car, toyota celica... I've experienced ABS on all of those, except for the celica and the viper (no abs one either) of course. And I'm quite familiar with threshold breaking. The ABS on all of these other cars never felt anything like this. I totally agree. It scared the living daylights out of me when it happened, but i'll just hope that someone else gets it fixed, and then posts on the board so I can tell the dealership what to do.

I had a 95 GMC Jimmy that did this! I almost had numerous accidents due to the ABS engaging on bumps under light-moderate braking. I wanted to sell the car, once I figured out this was "Normal" and not a fluke type thing. I can see the class action suit on this one..... Brakes that disengage to cause accidents!
Bobby Hopp
'01 Audi 225TT Quattro coupe

I have not noticed any unusual braking behavior in the few weeks that I have been driving my WRX, but some of the reports here definitely sound like there might be an issue. We probably won't be able to figure out on a message board it there is a problem with all cars, some cars, of if this is "normal".

I would encourage everybody who observes these problems to report them to their dealers. Especially if you can reproduce it, please have it checked out! If the service technician doesn't give it the proper attention, talk to the service manager, your regional service manager, etc., until you feel like your concerns are addressed. If there really is a malfunction here, it needs to be found and fixed as quickly as possible, before people start crashing their cars. And while it makes perfect sense to validate your observations with other owners, discussing it on a message board will not solve a problem. When I saw my dealer about a less serious issue, and mentioned how it had been discussed online, the technician said (paraphrased) that he doesn't care about the issues that people report on the internet, he only cares about issues that customers bring to him, and that SoA informs him about. So let them hear it!

My 98 M3 did the same thing. Would scare the CRAP outta me but usually if I backed off break (disengaging ABS?) and hitting the brake again then it would bite.

OK, having experienced on 2-3 occasions the previously discussed ABS problems, I did some experimenting. It was rainy and slick outiside today, so on a few occasions I engaged the ABS in a safe spot where I knew I wouldn't get into trouble if something went wrong. On all tests it worked just as it should. I could definitely feel/hear it working, but the pedal did not drop, and I felt that I had maximum braking (for the surface) at all times. Never once did I get the OH-GOD, NO BRAKES feeling that I've experienced a few times on the dry pavement. The pedal stayed firm and although I stayed on the brakes hard, it returned control to me as soon as the wheels regained grip. I did not have to lift the pedal to disengage the ABS. I also felt the 4-channel system working as I could feel the car yaw slightly from one side to the other as the individual brakes worked independently. When the problem ocurred it was as if ALL the brakes released regardless of the fact that only one wheel had lost contact with the pavement for a microsecond. I just wanted to share this with you, and maybe get some feedback.

I haven't had this problem with the Legacy yet, but my 97 Chevy S10 used to do this when I first bought it.

Hitting a bump under braking would sometimes cause the ABS to activate. The brake pedal would go to the floor and the truck would keep rolling forward like it had no brakes. Not fun when you are approaching a busy intersection. And this was on perfectly dry roads.

After about a year I replaced the brake pads with some good quality aftermarket ones. Made a big difference in the way the ABS system responds and I haven't had the problem occur since then.

Good tires with better grip than the stock ones should help as well since they will be less prone to lock up.

-Steve

First, to all who believe that SOA is trying to "sweep this under the carpet". If you stop and think for a moment, I'm sure you will realize that the liability (if nothing else) would preclude them from taking a position like that.

I experienced this anomoly one time. As a result, I spoke to SOA and the tech dept. is on the case. My car is at the dealers at this moment being checked. I'm sort of a test case, since apparently very few calls have been made about this problem. So, I would suggest that anyone who has had this experience should call SOA (be nice!) and let them know what has happened. I know from personal experience that nothing is more difficult to fix then the "it only happened once" type problem. Without symptoms a cure is hard to develop.

SOA logged the problem, but said that I should take it to the dealer. I called the dealer and they said I should bring it in. I agree, but the dealer is 2hrs away. I might be able to get roadside assist to haul it in for me, but I'd still have to go and pick it up. That sucks.... I'm sure they won't find anything wrong with it anyway. Could some of you that live closer to your dealership take yours in too? I'll see if I can schedule an appointment anyway.

Okay, I'm in...happened to me this weekend for the first time. Almost went into an X5 at a stop light. That wouldn't have been pretty. Scared the S*@* out of me. I guess nobody knows until they bring it in, but I have a feeling that dealerships are going to say:

a) "We drove your car for hours and had a whole lotta fun, but never experienced the problem you discussed...we think you're nuts"
or
b) Yeh, it seems like what you are saying MAY be true, but we don't think there is anything that can be done. Drive safely.

Whaddayathink?

Or they could say.... "We couldn't duplicate your problem, but we figure any problem you're having is probably due to you driving the car too hard, and we consider that abuse so we're not going to cover this repair even if we find something wrong."

:rolleyes:

Originally posted by Zoomer
First, to all who believe that SOA is trying to "sweep this under the carpet". If you stop and think for a moment, I'm sure you will realize that the liability (if nothing else) would preclude them from taking a position like that.

Your position is naive. After talking with SOA about other issues and listening to their well rehearsed corporate excuses, I wouldn't put ANYTHING beyond them.

When I talked to the SOA rep, she requested that I call SOA when the appointment is made for the inspection. She told me that they hoped to find something fixable, but they wanted to know if no problem was found so that they could investigate further.

Okay, I'm volunteering to be the point man. If you have experienced this problem please email me at "hutchcpm@aol.com" with the following info:

1. You name and email address
2. your VIN #
3. date of mfg. (from the sticker inside your door)
4. weather conditions at time of problem
5. road conditions at the time

I have a contact at SOA that wants to help but they need info.

Here's a little more info on the problem:

Some cars (Including Impreza's, Forester's & Legacy's) could have a bad master cylinder. My RS did what the first post describe's at around 4,000 miles. It was IMMEADIATELY diagnoised by the dealer and SOA as a defective master cylinder and was replaced under warranty. No problems since, brakes work great during day-to-day driving, autocrossing and rallycrossing.

Unfortunately there are other things that can cause similar symptoms and I don't think that everyone's master cylinder is bad. Things like:
- Unfamiliarity with the ABS system
- Those crappy RE92's
- Loose or rough surface
just to name a few.

It sounds to me like SOA is having trouble determining which problems are legitiment brake system failures, and which are caused by some other reason.

I doubt that SOA is trying to "sweep this under the carpet", and no I am not naive...I just have a great dealer that works withSOA and me to get problems solved. Sadly, not every Subaru dealer can make that claim. Matter of fact, when I have had to call SOA they treated me fairly and did not give me any "excuse" that was "well rehearsed". Instead they either helped me solve my problem, or pointed me in the proper direction to get the problem solved.

Hope this helps some of you out.

OK - I've probably driven 10 (or more) WRXs under all kinds of conditions and have not experienced this.

My brand new WRX does not have this problem (I've tried it), neither did my old WRX.

Your assertion "I believe this is a common problem in all 2002 WRXs." is therefore false, unless you are describing a scenario I have not tested.

I don't doubt YOU (and others) either have a real problem or perceived problem, and definitely should get it checked out by the dealer.

Glenn

Ok, I just wanted to state something. First of all I personally believe that SOA isn't fully aware of the problem. They've got a few reports of a few drivers complaining about ABS problems. They've probably got a few complaints about aliens living in gloveboxes too. I'm a tech manager for a small computer company, and I admit that when I hear something really unusual/unlikely I try and chalk it up to user inexperience. Sometimes I'm wrong though. I've also seen some really rare software bugs, that only happen when you hold your mouth right under a full moon and you're wearing a plaid shirt. I've experienced this braking problem, and I can't believe that it was designed to work in this manner. And I've tried and tried to duplicate it, but I can't. Only happens when I'm not expecting it, and only twice in 10K miles. I'm familiar with ABS systems, their motors, valves, sensors, pumps, control systems, etc.... Admittedly the setup on the subaru is more advanced than any I've worked with before. I'm used to 2 to 3 channel systems that work from wheel slip alone. I understand that the Subaru ABS also uses accelerometers and some complex software to determine the optimum manner to brake. All ABS systems made in the past 5-6 years have not only failsafes that switch the system to standard brakes if the accumulator or pump pressures are low, but don't hesitate to light a big red indicator on the dash telling you that someting isn't right. I'm confident that it's a software problem or a sensor glitch. I'm going to take the WRX in for inspection as soon as I possibly can, but I KNOW that they are not going to check what I think needs to be checked. They will pull codes, check connections, fluid levels, pressures, and take it for a test drive. Somehow we'll have to make enough noise that a Subaru Engineer is going to take apart the ABS control system, and scrutinize every line of code, and every ABS circuit for possible tolerances or conditions that weren't anticipated. Even if I had crappy tires, bad driving habits, or even got under the car and started cutting wires, that's no reason for the ABS to go berserk. The electronics/controls are SUPPOSED to be failsafe and switch me to regular brakes when something goes wrong. I don't want to blame anybody, I don't want to sue anybody, and I'm not claiming to be the god of all things ABS. I'm just sharing my knowledge and experience in the hopes that we can be productive in finding a solution. And I KNOW, without a doubt, that there IS a problem with MY WRX. Thanks for reading my long rant.

Wow. Quite the thread. It seems that some people must have different cars. I know that people tire of my saying this, but I have tried braking my WRX in every situation that I can think of:

On gravel, on steel drawbridges that we have in Chicago, rumble strips, you name it. Hell, I can barely get my ABS to activate! Then again, when bumps make the ABS activate, I release pedal pressure then re-apply the brakes, just like they taught me in Skippy school. No problem.

But I have never, ever experienced what many are calling a secret Subaru plot. But realistically, after what happened to Ford with the Explorer, do any of you honestly think that ANY car manufacturer would voluntarily or knowingly issue a car, especially a performance car like the WRX, with substandard brakes, or a system that can make the pedal go to the floor over precisely the kind of stuff that the WRX is supposed to shine on?

I think not.

Probably the most important thing is that any of you experiencing this problem, should complain just as vociferously to your dealer as you do to this board. If you don't get satisfaction from the dealer, find the area SOA rep. Every region has one. Subaru cares about the WRX like they have no other car since the first generation Outback.

Here's when I can get my ABS to go off...in the rain, if I apply the brakes firmly and abruptly. It's also not the kind of braking that I do, and is the kind of braking that means I've probably overdriven the car (not that I'm implying that anyone here did such a thing...this is my experience alone).

Those who know me, know that I have DMS Golds on my car, with 17" P1s and Dunlop 9000s. But even with the stock suspension, I never noticed this problem. Some cars are different, apparently. But to blame Subaru for this, and to accuse them of sweeping it under the carpet defies logic. The Brit boys drive the piss out of their cars and to my knowledge, they haven't been experiencing similar problems, unless I just missed it on Scoobynet.

Something is wrong, if this stuff is going on. Go to the same spot, and duplicate the conditions. Since this is happening when it's dry out to most of you, this should be an easy thing to do. If it's a problem with the system, it should be duplicatable. But every ABS car that I have ever driven, when the wheels are unweighted, feels like the brakes have stopped working. Getting off of, then right back on the whoa pedal brings things back to normalcy.

There are a couple of people who have taken their cars in, and are having the dealer check out the systems. I'll be very curious to see what happens.

Kevin

OK - Just have to add my two cents worth. :monkey:

I concur with DammitBeevis that it could be a software error deep in the digital bowels of the ABS system. Who knows how many factors have to be just right before it misbehaves. I think the critical issue is whether or not it can be reproduced. Being in the software industry, I know how hard these things are to track down unless they can be reproduced. As long as this problem cannot be shown to exist SOA will not go to the expense of rectifying it. Also, the software may be another vendors code which complicates it even more. I am just speculating here - just another take on the problem. :rolleyes:

If anyone can reproduce this problem then document it as best you can and submit it to the regional service manager or higher. Only when it can be proven that there is a problem, will they spend resources on the solution.

That probably wasn't worth two cents.

I won't make it tomorrow, but I'm going to try duplicating the conditions in the last place it ocurred. I think I can probably whack the same bump at same speed under braking as I did before. I'll let you know what I find out.

Sounds like Zoomer knows what he is talking about. If they get information, they can maybe sort out what is going on.

The problem is when there are other "issues" getting mixed in. i.e. Brakes have grooves so they are all defective and it is a vast conspiracy.

Also, if they start throwing parts at the car for something that they "think" may cause it, they may mask the problem, but not fix it. If they don't fix it, it could happen again.

So, go with Zoomer. Get it to a dealer and have them check out the obvious stuff. Call SOA and let them know what you experienced. Don't call them if you didn't experience it just to say that you read it on the internet.

If the dealer doesn't take you seriously - get SOA on them.

Just my $.02. The more info. we provide the better things will be towards a fix. P. S. - I can't get my Rex to do it - and I really tried.

Spider

i dont think this is only a problem on 'some' WRX's or Impreza's.
i have put 7500 miles on my rex and have only experienced it twice. the condition have to be right. and my wife's New Beetle does NOT do this.

when rolling at only 25 or 30 mph, you should be able to stop in like what, 30 feet? if you are applying the brakes HARD, and whack a bump you WILL know what im talking about.

TRY THIS: find some railroad tracks... make sure nobody is behind you and there is no train coming :p ..... apply your brakes hard RIGHT BEFORE you hit them.... when you hit that first track, your brakes will go right to the floor and you will continue to roll like your arent even applying your brakes!!! its scary! they will catch in a couple seconds, but by that time you could have already hit something. i can repeat this at will. AND have done it in a friends WRX!

Bob :mad:

Hey Westy, this was one of the things that I tried during my attempts to replicate the brake problem, and my car just stopped. The ABS did activate, but without any drama. Just a nice, smooth stop. I was quite impressed.

I forget what else I did, but if you search for a thread called "GTGUY's WRX brake test" or something like that in this forum, you can see what I did, and what happened.

Kevin

I tried it too Westy and the ABS operated as expected. I used two different sets of tracks on my test, one set was fairly smooth and the other was rough. Neither produced the effect you described. I will try one more time though because the ABS didn't activate until I hit the tracks. I will try to activated it before I get to the tracks to see if this makes any difference. I don't see why it should but in the name of science I will be thorough. And I have one more set of tracks to try.

i own a 2000 2.5rs and have experienced the same problems when going over rumble strips or bumpy road areas while braking.
I've been a Tech for 14 years and have never experienced this in other makes or models. I thought it may have just been my scooby but apparently it is a problem across the board. I'm going to research this and if I find anything I'll be sure to post it.


jediknight.

Originally posted by Zoomer
First, to all who believe that SOA is trying to "sweep this under the carpet". If you stop and think for a moment, I'm sure you will realize that the liability (if nothing else) would preclude them from taking a position like that.



uh, have you never seen Fight Club? remember "The Formula" ? This really is the way they operate. It's not like SOA is some caring big brother... they are concerned about exactly one thing: the bottom line. This is how it is with ALL corporations and if they think they can get away with it without losing face, they will try.

whether or not they think they can get away with it depends on how much this problem is reported to people OTHER than subaru.

I disagree. Subaru isn't like Ford, where a multi-million dollar lawsuit or three won't kill them. There is absolutely no way that the company would knowingly put cars with a potentially fatal problem out there. They sold about 190,000 cars last year. Hell, Toyota sold more Camrys than that! Were publicity to get out about a brake problem, the company's North American presence would be in serious jeopardy. Look at how long it took Audi to recover from the "unintentional acceleration" rumors.

People at Subaru drive the cars, dealers drive the cars, their loved ones drive the cars. Who among us, even the most heartless, would voluntarily put their friends or family in harm's way by putting something that is knowingly defective out there?

Has anyone been able to duplicate the problem? I know that a few guys were going to try.

Kevin

Here is a thread posted in general that has two instances where the dealer was able to fix the issue, two different items, one from toby in the first post, second from StormRacing about 12 posts down (& mentioned in first post)

1. ABS module replaced
2. sensor replaced

http://www.i-club.com/forums/showthread.php?threadid=108976

PLEASE take any bad braking cars to the dealer as soon as possible!

Who among us, even the most heartless, would voluntarily put their friends or family in harm's way by putting something that is knowingly defective out there?

The same people that work for tobacco companies?:rolleyes:

Or those who put (and kept) the fuel tanks in GM trucks outside the frame rails?

Sorry, but without hijacking the thread, tobacco can't be compared to allegedly defective brakes on a car. If someone chooses to smoke, party on. But brakes, especially on a performance car, are another matter. They are a critical component.

As far as the GM fuel tank "test" in which cars on the telly blowed up real good...please.

I refer to my previous statement.

Kevin

Slide, thanks for the info, but I don't think this is a solution to the exact problem we are having here. It seems the problem that was solved in your linked thread was an "easier" one to fix... i.e. the problem was obviously apparent and an isolatable component was at fault.
With our problem, the main problem is that it's impossible for the usual routine testing to find the problem.

I'm going to email Zoomer with my info and hope that he's making progress. (Zoomer, please keep us posted as what to do and what's going on) But, I'm afraid it might depend on one of us being able to reliably replicate the situation, then go to a dealer and ask the manager or better yet the owner to take a test drive and make him wet his nice suit pants. then something might get done.

As I illuded to before, this is not a problem, unfortunately, where you can drop your car off for service and say "oh, by the way the ABS screws up when I hit bumps" and they can diagnose it and fix it...it just isn't that type of problem...which is a shame since it is such a life threatening issue. Once again, today, I almost rear ended someone when I was doing 25 mph and he cut in front of me on a bumpy road. I had to head for the shoulder and almost hit a curb to avoid ramming him. This is my 5'th or 6'th time it's happened in 2800 miles.

Jeff C.
--who now drives with one hand on the e-brake :mad:

Originally posted by SlideWRX
Here is a thread posted in general that has two instances where the dealer was able to fix the issue, two different items, one from toby in the first post, second from StormRacing about 12 posts down (& mentioned in first post)

1. ABS module replaced
2. sensor replaced

http://www.i-club.com/forums/showthread.php?threadid=108976

PLEASE take any bad braking cars to the dealer as soon as possible!

Clearly nobody here can fix it, so you should take it to the dealer and hope it happens when they drive it. The sooner the better, before you or someone else gets hurt. If you did rear end somebody, think how hard it would be to prove there is a defect with the ABS.

Just an FYI
I've gone through the same intersection, hitting the same bump at the same speed with the same amount of braking quite a few times (don't have an exact count, 15 or so maybe). And I cannot duplicate the problem. In fact, I can't even get the ABS to engage under the similar conditions. I've got to practically stand on it to even get the ABS working in this spot. And then I just get a chirp as the tire bounces through the bump/hole. Maybe I hit a stone or something that one time. I dunno. Anyway, just thought I'd let you guys know. Still trying to find time to take it to the dealership.

I spoke (email) with my friend at SOA this morning, they have informed FHI of the "reported" problem. SOA has been unable to duplicate the problem, FHI same deal. FWIW me either. My friend is running around in a WRX trying to make it happen .. no luck so far. I'm told that the "big wigs" are involved.

We need data! I've gotten several emails with the info I requested but not many. They can't fix what they can't find.

Tell them to come to my house..... I have a little hill in the driveway and the other day I drove over it and almost hit the garage because the stupid brakes didn't work.

Happened to me this morning. About 3 miles from my house, approaching a stoplight at about 20 or so. Braked normally (I tend to roll to the stop, not stop abruptly). Hit a patch of rough road and the abs kicked in. If I was going any faster into the stop I would have definately rear ended the car in front of me. Talk about being pissed off. I'd guess this is about the 4th or 5th time it happened to me. The real problem is it is totally unpredictable. It's got to be an interplay between alot of factors.

-jb

As I've said before, the unpredictability and difficulty in replicating this problem is going to be what kills us (hopefully not literally) in finding and fixing it. Good job with posting your issues, and everyone please make sure you email Zoomer with your info.


For what it's worth. It's happened to me 5 or 6 random times (2 different places have caused it twice each). But, last night I hit railroad tracks perfectly perpendicular, on purpose, and hit my brakes, and the abs kicked in but the car came to a nice abrupt stop! I dont' get it. My new theory is, it's either a whole slew of random factors, or that it takes all the wheels being "locked"/airborne at different milliseconds to fool the computer and mess it up, unlike hwat happened in my railroad track test where the two front wheels would have "locked" at the same time.

Jeff C.

For those of you that just got on this boat, here's links to a couple other threads on the same subject, the second one contains some technical info that some might find enlightening(sp?)
http://www.i-club.com/forums/showthread.php?s=&threadid=96438
http://www.i-club.com/forums/showthread.php?s=&threadid=76823

OK, I've seen threads in which people complain about the ABS system on their cars and I thought A) this is a somewhat rare problem a minority of owners are experiencing or B) it was a bunch of whiners who are overdriving their cars and blaming the ABS system for not stopping them. Sorry, but that was my assessment of the situation.
Well....it happened to me for the first time at ~8,000 miles. I was sent down a detour and I goosed the car up to about 35 mph when somebody pulled out in front of me and stopped (idiot-but that's another story). The weather was clear and dry, but the portion of the road where the right of my car was rolling had light gravel dust on it from construction. I hit my brakes hard (as I have been forced to do on two previous occasions) and the ABS immediately kicked in - the "bumping" on my foot, etc. Then the pedal just dropped (not to the floor, but close) and I had no brakes for at least a second or two:eek: I thought I was going to broadside the moron who decided to park in front of me! The second or so when I had no brakes gave me enough time to release then re-engage the brakes at which point they bit, under the same road conditions...I know I should not pump the brakes on an ABS system but I was a bit panicked and thought I was going to hurt somebody, so insincts took over.
Unfortunately, the road is now clean so I cannot reproduce the problem but I apologize for thinking you folks were "whacked". I will report this to my dealer.
I am definitely going to be super careful the first time I drive in the snow and will be prepared to disable the system by pulling the fuse if I think it is appropriate.

I had experienced the problem before, but I think it's not a defect instead a design issue.

I experience this issue whenever I brake into a railroad cross. ABS would kick in as the tires were "unloaded". When the car settles, I wouldn't be able to gain more brake power when step harder on the brake padal.

I think ABS is just trying to do its job at the "wrong time".
When the car brakes and tire gets unloaded, wheel gets locked up maybe for a split second. ABS sense wheels lock up at X amount of brake pressure thus it begin to bleed the pressure slightly to allow the wheel to spin again.

However, ABS doesn't know traction condition has changed after the car settles. It still think the traction condition is as poor as the moment you did the "jump". So when you try to apply more brake pressure, ABS just bleed them away to prevent wheels from locking up. I believe this process would keep going for about 2 seconds and you can hear a ticking sound from under hood.

How do I deal with this? Release the brake completely and reapply the brake again. Release the brake fully will disengage the ABS and you will be able to brake much harder since the tires do have the traction again.

Yeah Jason, but that is NOT how ABS is supposed to work. It is supposed to modulate the brakes several times a second.

Two comments/questions. Do any of the people that this has happened to have aftermarket wheels/tires, and any sort of brake upgrades? And how many more (I know that DammitBevis did) of you have tried to duplicate this problem. It seems like it should be duplicatable, if it's a mechanical deficiency.

Kevin

gtguy

I don't have anything aftermarket on my car.

As far as it being duplicatable, there are plenty of comments, including mine, about that earlier in the thread. It's not easy...

Jeff C.

OK I sat down and thought out what could cause this problem using the information from the Subaru Service Manual posted here:
http://www.i-club.com/forums/showth...&threadid=76823

Here's how I understand it.
The wheels never "lock" on the WRX, they will only slip up to 30% as defined by "slip=100*(vehicle speed-wheel speed)/vehicle speed.

At 25MPH, the ABS would activate when wheel speed dropped below 23MPH. I can assume on a single bump that the CPU would have a pretty good idea of the actual vehicle speed and that this would work OK.

HERE IS WHERE MY ASSUMPTIONS START

OK the CPU is now deciding how fast that wheel should be turning. It's logical to assume that it can't rely on the speed of the other front wheel for vehicle speed reference, since you may have just hit an ice patch with both front wheels. Following the same sort of worst-case logic, you wouldn't rely on the rear wheel speed either since the driver may have slammed on the brakes and they could be decelerating rapidly as well, but not reached the threshold yet. This is where the G-Sensor comes in. It's measuring the decelration and comparing it to the reference taken before the skid started to generate a very good estimate of current vehicle speed. Sounds good right?
So, what happens if another bump screws up the G-Sensor reading so that it over-estimates the vehicle speed by even just a tiny 2-3MPH. Even though the wheels are at 0% wheel slip, the computer may be calculating the threshold 8% wheel slip for all four wheels. This is in the ideal range for the ABS system, so it's happy, it thinks it's doing it's job correctly, and sees no reason to increase brake pressure. It also won't be using any of the wheels for a vehicle speed reference, and the wheel acceleration threshold needed to de-activate the ABS will never be reached because in reality the wheels are turning as fast as they can. So that leaves you stuck at whatever brake pressure level you were at when the slip occurred.
The only way to recover is to release the brakes to reset the ABS Assumptions, or to wait until some sort of failsafe in the program realizes how unlikely it is to maintain perfectly even wheel slip on all four wheels and stops the silliness itself.

Well, what do you folks think? Sound plausable? I love to be criticized.:D

It's certainly plausible. As is any other reasonable assumption/theory at this point. You cna't negate any of these ideas unless you're a Subaru tech who built the system. Hopefully some important people will see these ideas and ask the correct people.

Jeff C.

I suspect it blends the calc'd speed from the g-sensor with the VSS or ABS tone measured speed.

If I were writing the code, I would ONLY use the g-sensor when two or more wheels appeared to be slipping.

When just one is slipping, the measured speed is much more likely to be true.

Glenn

Keeping in mind this is all hypothetical.
1. Slip hits threshold on right front wheel.
2. CPU is using other 3 wheels for vehicle speed calc.
3. Brake pressure is still increasing on other three wheels.
4. Bump causes Decel Calc to error on the fast side.

5.1 CPU ignores other 3 wheels and assumes they are slipping
because of G-Sensor Readings. (original theory)
(low braking power results, can reset by current wheel
speed if an error is detected)
-or-
5.2 CPU ignores G-Sensor and uses wheel speed that MAY
be errored by slippage. (opposite original theory)
(may result in complete lockup, actual vehicle speed would
be difficult to re-estimate without releasing the brakes
completely for a moment)
-or-
5.3 CPU averages G-Sensor (poss too fast) with Wheels (poss
too slow) (Glenn's theory)
(erratic results, but most reliable, could follow 5.1 or 5.2
effect)

Further descriptions:
5.1 Very possible situation, would need the fewest subroutines to make it work. Programmer could easily not take into account such sensor deviation given it's 'normal' specifications. Low braking power wouldn't be acceptable if bad sensor readings are taken into account. (possible oversight in engineering)

5.2 The lockup would be instantly detectable, and you would only need to release the brakes for a moment to recover. Worst case being that you're on a VERY slick surface, and there isn't enough time/friction to accelerate the wheel back up to full speed after being locked. How to know when to ignore the G-Sensor would be the trick. (not reliable on really slick surfaces)

5.3 Most complex situation, would need code to deal with either situation. It would be correct the most often, but may not act consistently. (sounds familiar)


and yes, I'm bored.....

Where is the G-Sensor for the ABS located anyway? Seems like the way to test this would be (in a safe and controlled environment) to bump and/or mis-orient the sensor while in operation. Technically bumping the sensor while not changing it's orientation SHOULDN'T alter it's readings since everything should average out, only instantaneous readings would be in error. Mis-orienting it would show how much the calculations relied on it.

Originally posted by Porter

By the way, your statement about ABS being designed to make braking distances 3-4 times longer is TOTAL BS. The whole point of AntiLock brakes is to reduce braking distance by preventing wheel lock. A rolling wheel stops sooner than a sliding wheel.... remember? The ability to steer around an obstacle is merely a convenient bonus.


Sorry, but the primary purpose of any ABS system is to allow the driver to retain directional (steering) control during hard braking, rather than letting the wheel lock up and slide. A rolling wheel stops sooner than a sliding wheel? No, a rolling wheel steers better than a sliding wheel. Did you read your owners manual? "The ABS system does not always decrease stopping distance. You should always maintain a safe following distance from other vehicles. When driving on badly surfaced roads, gravel roads, icy road, or over deep newly fallen snow, stopping distances may be longer for a vehicle with the ABS system than one without." The "ABS Stops on a Dime" claim is salesman-speak. Those of us in the back shop know better.
ASE Master Tech L1 certified

You have obviuosly never experienced what we have.
Again, as was stated by another member, ABS should NEVER, no matter on what road conditions, ice, mud, gravel, etc, EVER cause the stopping distance to more than DOUBLE. The Subaru ABS is flawed - period.


Originally posted by WRXSTi69


Sorry, but the primary purpose of any ABS system is to allow the driver to retain directional (steering) control during hard braking, rather than letting the wheel lock up and slide. A rolling wheel stops sooner than a sliding wheel? No, a rolling wheel steers better than a sliding wheel. Did you read your owners manual? "The ABS system does not always decrease stopping distance. You should always maintain a safe following distance from other vehicles. When driving on badly surfaced roads, gravel roads, icy road, or over deep newly fallen snow, stopping distances may be longer for a vehicle with the ABS system than one without." The "ABS Stops on a Dime" claim is salesman-speak. Those of us in the back shop know better.
ASE Master Tech L1 certified

Just so you folks know. I ran into ONE situation where ABS more than doubled my stopping distance. It was a parking lot with some nearby construction, the previous heavy rain had washed a 1/4" thick layer of really gooey mud onto the pavement. If my tires would have just locked and dug-in and piled the mud up in front of themselves, I would have stopped in a few feet, but NOOOO, as soon as the wheel stopped turning, they'd release and suck some more slick mud underneath themselves, I might as well have not used the brakes. I thought quickly and hit the parking brake, and as soon as the back wheels started dragging I stopped. I would have liked to have a switch to turn them off at that time though.

Ok D.B. We'll give you that scenario in causing ABS to horribly affect stoppnig distance! But how RARE is that!!?

Jeff C.

Originally posted by WRXSTi69
A rolling wheel stops sooner than a sliding wheel? No, a rolling wheel steers better than a sliding wheel. Did you read your owners manual?
It obviously steers better, nobody questions that. But it also stops sooner. It might not be in your owners manual, but any high school physics text will explain the difference between the two different coefficients of friction (static and kinetic).

You get the optimum braking power by braking as hard as possible without ever blocking the wheels. The reason why ABS can make your braking distance longer is that it doesn't achieve this goal. It will release the brakes when it detects blocking (very quickly!), but it doesn't prevent the wheels from ever blocking. So a perfect driver would be better than ABS. But nobody is perfect, and most drivers are very far from it. That's why ABS reduced the braking distance for most people, especially under difficult conditions.

Peace please. You are both right but too stubborn to admit that the other one is too. The points that you are making are not mutually exclusive. You both get to be right.

BTW, I love ABS. I just don't like not being able to trust the WRX ABS all the time. I was at least aware of situations in my old pontiac that would confuse the ABS (mud, grass, loose gravel). I can accept the give-take situation with ABS. It's the unrpredictibility of these new problems that bother me.

Well guess what?

I duplicated it, or I think I did.

~25 over a speed bump (at work), with only the right wheels over the speed bump, and brake hard.

Got some ABS going over the bump, yet the right front kept modulating even after I was beyond the bump.

I was able to stop fine. Firm pedal. (your car still may have a hydraulic problem).

Also bear in mind I have PZero Rossos, so YMMV.

Here's what I think is happening:
the brakes are grippy enough that as soon as the solenoid switches off bypass, and the caliper grips again, the tire skids again instantly, and this of course triggers the ABS again.
And repeat.
And repeat.

That is kind of what is supposed to happen with ABS, but if it hadn't triggered in the first place over the bump, the ABS wouldn't have triggered on the flat bit by itself, so it appears that being triggered by a bump induces a state where the ABS activates where it wouldn't have.

But then again, this problem should just show up with normal ABS activation, but then you'd be much closer to the threshold, and not beyond it.

The only way to diagnose this is with some data acquisition from all four tone rings and valve solenoid outputs.

If this is "the" problem, I don't think it is a firmware bug per se, more of an ABS design issue. I expect they could fix it by having some "dead time" before the solenoid fires, or making the activation a bit less like a square wave, which might also harm braking.

I wonder how the Bosch systems handle it?

Glenn

Did it "feel" like you lost about 50% or more of your braking ability? I mean, if you were trying to stop at a stoplight, and this happened about 15 ft before the light, would you worry that it might not stop in time? That's how I would characterize it. Like all of the wheels lost braking power, not just the one?

^
|
|
Sorry, that was me, forgot to logout my Wife first.

^
|
|
Sorry, that was me, forgot to logout my Wife first.

Did it "feel" like you lost about 50% or more of your braking ability? I mean, if you were trying to stop at a stoplight, and this happened about 15 ft before the light, would you worry that it might not stop in time? That's how I would characterize it. Like all of the wheels lost braking power, not just the one?

Well, it wasn't underwear changing time. It felt like I maybe lost 20-40% of the stopping power, and had a firm (but buzzing) pedal. I had no real problem stopping.

Again, had I not hit the bump, it wouldn't have been cycling braking that hard on that surface. The issue is how long the cycling lasts, I could understand it happening for a few feet, but this happened until I had basically stopped.

It isn't clear to me that this isn't what any other ABS system might do. Time to hit the books again.

Glenn

To all:

I just purchased a WRX wagon and have to say that I haven't experienced this phenominon with this car, but have with two other very highly regarded sports cars that I've owned:

94 RX7
98 BMW M Roadster

Both have ABS and in one instance with the M Roadster about 6 months ago, thought I was going to die. I had to make a panic stop about 1/8 mile before a freeway offramp. The car in front of me dead stopped and I slammed my usually increadible breaks. They started to lock up and pulled to a rough patch on the side of the road. The car slowed, but then the brakes let off as I started steering onto the shoulder knowing if I didn't, i'd rear end the car in front of me. The brakes behaved exactly as I've seen described above. They didn't stop the car, they slowed it while still allowing me to steer. It scared the hell out of me and I almost went completely off the shoulder. I had the brakes checked by BMW and they basically explained the same behavior over unevensurfaces under heavy braking that was described above. I also had a similar less severe incident with the RX7.

What I'm trying to say is I don't think this is a Subaru issue, but as pointed out by others, a ABS issue. Also as someone else pointed out, I'd highly recommend taking your car to an open lot and try panic stopping it several times, several different ways under controlled circumstances so you know how the car will behave. I do this every time I get a rental car. You'll be amazed at how it will affect your following distances. It's what I usually recommend to people I know who tailgate. :)

Hope this helps someone.

Glenn,
That sounds about right, I'd be willing to bet the 'feel' is proportional to the panic level at the time.
Was it repeatable? If so, you think you could get the critical dimensions of that speed bump for us? :D (That'd be fun trying to explain to somebody walking by)

I have not tried to repeat it.

I just changed a bunch of stuff on the car, so not sure any further testing on my car will be valid.

I'll try tomorrow though. :)

Glenn

I think what might be going on here is "yaw-monent buildup delay *1". Yaw-moment is the tendency of a vehicle to turn about a vertical. For instance, if both right tires are on a low friction surface like sand or ice, while both left tires are on a high friction surface like dry asphalt, then the car would tend to turn left under braking. This tendency will vary from vehicle to vehicle, but tends to be greater on smaller cars (And I believe the WRX sedan's wider track may also increase this tendency). To counteract this tendency, the ABS on smaller cars is sometimes supplemented with "yaw-moment builup delay". This feature delays the build up of brake pressure to the front wheel thats on the high friction surface (has the most traction).

Let's assume for the moment that the Impreza's ABS has this feature. If the ABS is "inadvertently" triggered at one of the front wheels by a bump, then the system may interpret that wheel as being on a low friction surface, thus applying "yaw-moment buildup delay". Now two things are happening. Brake pressure is being modulated at the wheel where ABS was "inadvertently" triggered, and the build up of brake pressure is being delayed at the other front wheel. Both of which would equate to a greater stopping distance. Yes, ABS may be able to stop faster in some conditions, but that's compare to a locked wheel. In the case at hand, the wheel in question probably wasn't even close to locking before hitting the bump and triggering the ABS. I believe that modulating brake pressure at a wheel that doesn't really need it will only increase stopping distance.

How does pedal drop fit into the equation? I believe most newer 4 channel ABS schemes use accumulator chambers to temporarily store large amounts of brake fluid as the means to reduce brake pressure. These accumulators are used in both modulating the brakes and in "yaw-moment buildup delay". This accumulation of brake fluid would result in the pedal dropping without and increase in stopping power.

Since we are all theorizing here, let me throw out another theory. It seems that leading theory is that the wheel hitting the bump(s) is becoming unweight and slowing faster than the others. Thus "inadvertently" triggering ABS. Well what if that wheel is just following the irregular surface and thus travelling a greater distance. This could also possibly trigger "inadvertent" ABS engagement. Just a theory.


Also, have any of those who have experienced this problem had their brake pedal's reserve distance check? If it were less than the minimum requirement per the Owners Manual, you could very well bottom out when the ABS kicks in. Also of note, our left hand drive Imprezas have less pedal reserve than the right hand drive cars. The right hander's pedal has almost an 1" more travel before it would hit the floor.

*1. Bosch Automotive Handbook 4th Edition

My WRX also experiences a similar problem. When braking on rough surfaces, braking distance is greatly reduced VS a non ABS equiped car. I have no problem with the brake pedal bottoming out.

Under hard braking on a heavily traveled bumpy road close to my home, non ABS equiped cars normally experience wheel lockup, although just for an instant. These bumps don't greatly decrease the stopping distance since wheel lockup is instantaneous. In this case, the ABS system reacts very slowly in comparison to such a short duration wheel lockup and greatly reduces stopping distance. I believe in my case it is the wheels inability to remain in contact with the road that triggers the ABS, not increased distance traveled by the wheel.

Here's where I think the Subaru ABS system is flawed. If I only hit the bump with one wheel, as expected the ABS system is triggered. It feels as if the ABS system reduces braking force to the three other wheels, that can still apply normal braking forces, to match the amount of stopping power of the wheel that has lost contact with the pavement.

I live in Wisconsin where we drive regularly on snow. My first experience with ABS (on a rented grand am) scared the crap out of me. Having learned to drive on snow in non-ABS equpied cars I have found that if two wheels are on snow (say the right side wheels) and the left side wheels are on pavement, that you should just lock the wheels that are on snow and stop using the left hand side wheels that are on pavement. I learned when stopping for a red light that if the car has ABS, the left side wheels will only stop the car as fast as the right side wheels that are on snow are capable of. I believe that the Grand-Am ABS system was just a two channel system.

You ask, if this is true what is the purpose of 4 channel ABS system. Not having ever engineered an ABS system, I can only guess. I assume it is to allow the ABS system to reduce braking force on one wheel only. It seems as if the WRX ABS system is acting more as a 1 channel system, not a 4. If anyone has more indepth knowledge of the WRX ABS system, please post. Thanks

This problem definatly sounds like a
serious problem. SOA, just like other
automakers are in the business of
making money, so to replace all the
parts required for this fix is not cost
effective until they get pressure from
the government or multiple law suits.
Not to say SOA has done this, but they
are big business....

It would be best if everyone who has
had this happen to them, copy/paste
their thread entry to the following site:

NHTSA_Vehicle_Safety_Report (http://www.nhtsa.org/cars/problems/ivoq/default.htm)

If they receive enough complaints they
will pressure SOA to review/recall the
problem.

I know using the Govt for things like
this can take forever, but this is a
better first step for a fix. :)

Originally posted by Tsepic
Here's where I think the Subaru ABS system is flawed. If I only hit the bump with one wheel, as expected the ABS system is triggered. It feels as if the ABS system reduces braking force to the three other wheels, that can still apply normal braking forces, to match the amount of stopping power of the wheel that has lost contact with the pavement.

That's exactly what the "yaw-moment buildup delay" is suppose to do. It reduces braking force to the other wheel(s). Even if the brake pressure is only reduced at the other front wheel, it's likely to feel like its been reduced at all the other wheels since front brakes do a majority of the work. This feature is intentionally designed in to keep the car from pivoting around the front wheel that still has traction ("normal braking forces") when the other is on a slippery surface. Therefore, I would not say the flaw is that it reduces braking pressure, but that the ABS has been "inadvertently" triggered at a wheel that is not actually on a lower friction surface. If it wasn't for "yaw-moment buildup delay", most of the people complaining of this "problem" would instead be complaining about how dangerous it is that their car turns to the left or right when braking on asymmetrical surfaces (uneven traction/friction).

I also find it interesting that quite a few people feel we should bring this to the attention of the NHTSA. Well, I think they, and the Insurance Industry, are quite aware of the issues with ABS brakes. Go and read their web page www.nhtsa.dot.gov/cars/problems/equipment/ABSBRAKES.html . Things such as the pedal suddenly dropping and increased stopping distances are mentioned there. I believe there was even talk in the Insurance Industry awhile back about getting rid of ABS discounts or even increasing rates for ABS equipped cars because of an increase in the number of rear enders they were involved in.

I'm not a big fan of ABS, but I've learned to live with it. In snowy conditions I do my best to keep it from kicking in. And when it does kick in, I either let off and reapply or just press down as hard as I can depending on the situation.

Now none of this is meant to say that what people are complaining about here is not an actual problem. It's just that "normal" ABS operation is considered problematic by many, including myself.

Originally posted by Scottie
Therefore, I would not say the flaw is that it reduces braking pressure, but that the ABS has been "inadvertently" triggered at a wheel that is not actually on a lower friction surface.
Very interesting stuff about this "yaw-moment buildup delay", that explains why the braking pressure would be reduced at both front wheels when one of them hits a bump. There's one thing in this theory that I still don't understand: From the descriptions I read here (I haven't observed the problem myself), it sounded like the reduced braking pressure persists long after the bump. Once the wheel that hit the bump gained traction again, shouldn't this be detected by the ABS, and braking pressure should be increased again?

My last car was a 1993 RX-7 Twin Turbo (gone and missed, buit old and decrepit). Mazda had a recall abotu an ABS problem that involved repalcing a hose in the ABS system. It was a 5 minute repair.

The probnlem manifested itself on my car by the brakes barely working in reverse! The cure of subaru may or may not be as simple.

One problem with the WRX is the horrid RE92 tires. I got into the ABS yesterday when I had no reson to expect it. The WRX braking distances are disgustingly long becuase these tires ahve no grip.

I belatedly bedded in my brakes today at 1,000 miles. It has made a hiuge diffeence in the brak preformance. I don;t know if it has any affect ont he anti-lock question.

I have 2002 WRX sedan i too noticed that the abs would come on after hitting short bumps in the road that would make my tire jump up, or on rough pavement it definatly increases the braking distace alittle and i'm not looking forward to the winter because of it

tried to duplicate this issue.
Was not able to do so. I don't ever want to go through anything like this. Anyway, the approach to this issue is to ensure that the media gets this information if SOA decides to ignore this problem. 2020 or any consumer affairs organization would be a good start. I did not buy my rex for me to die in it. Anyway, hope the problem is solved. Peace.

I haven't noticed anything scary with the ABS in 500 miles of driving my new WRX, but the ABS does seem a bit twitchy, especially on bumpy roads. My 99 RS never had the ABS kick in on dry asphalt but my WRX does kick in when I don't think it should. It seems to be a little on the sensitive side and I have owned a RS, Outback, Forester, and a WRX so the comment "that's just how ABS is suppose to work" does not apply :rolleyes:

I recommend that all you guys that are having problems with your ABS just pull your ABS fuse and drive without for awhile. I'm pulling mine as soon as it snows. I drove all winter with the Forester's ABS disconnected and I acutally liked it better.

Mike:D

There are VERY smooth RR tracks (the kind with the rubberized surround) about 50 feet from a traffic light. I didn't catch the green for the first time and when I put my brakes on, I felt the pedal chatter and it DID feel like it greatly increased braking distance.

I'm lucky there was NO car in front of me all the way to the light (I was in the lead of the traffic platoon).

Not very happy about it. It looks to me that ABS only helps on ice and rain. Snow doesn't allow "digging in" and bumps are downright scary.

JL

One automotive company has addressed the phenomenom of ABS not allowing the tire to dig into the ground, Nissan. On their Xterra, they proclaim in the sales brocure that the abs will not activate on snow and other appropriate surfaces to allow the tires to pile obstruction in front of them and to dig through to grippier substances.

-Jason

My ABS Post- March 25, 2001 (http://www.i-club.com/forums/showthread.php?s=&threadid=31283)

I posted this 9 days after I picked up my car (3/16). 4 days later (3/29) in the rain, I was unable to avoid hitting someone who turned in front of me before I passed.

Did this ABS issue contribute?.....I'll never know.........

ABS Post, June 7 (http://www.i-club.com/forums/showthread.php?s=&threadid=38451)

Another interesting thread on this topic.........

Originally posted by dug-e-fresh
My ABS Post- March 25, 2001 (http://www.i-club.com/forums/showthread.php?s=&threadid=31283)

I posted this 9 days after I picked up my car (3/16). 4 days later (3/29) in the rain, I was unable to avoid hitting someone who turned in front of me before I passed.

Did this ABS issue contribute?.....I'll never know.........

Interesting...

I was cut off by someone in a Honda. I hit the brakes and got into the anti-lock. Taht was when I decided the tires had to go.

Pepople tend to underestiamte the tires contribution to the performance and handling of the car. My RX-7 came with Yokaham A022's. In the rain, I had to go around corners slower than anything else including Metros. Byt he time I got to the Proxes T1-s, I had a secure tire and could outcorner everyone in the rain.

My wife was with me during that incident. I told her these tires go - tires are cheaper than sheet metal and human body parts. She agreed.

Maybe we need to complain to DOT, especially since you had an accident.

The RX-7 was rated as stopping from 60 in about 113'. The Subaru is closer to 140-150. Witht he Proxes, my car stops about the same as the RX-7.

If you want all weather tires, look around, particularly the Toyo's.

FargoRS,
That's interesting. My experience has been the opposite. The ABS seemed to kick in more readily on my RS than my WRX.

One possible reason for this could be tire/wheel weight. I was running the stock wheels with 205/50R16 tires on my '99 RS that weighed in at 36 lbs. On my WRX I've been running the combo of 16x7 Speedline Comp 2s with RE730s which weigh in at 44 lbs. The extra inertia of this heavier combo may help to keep the wheel rotating when it becomes unweighted by a bump during braking. I'll be able to test this theory shortly, as my winter wheel/tire combo for the WRX weighs in at 36 lbs. I'll let everyone know if this seems to make a difference.

FargoRS:

My RX-7 had real light wheels and a variety of tires over its life. The last set were 245-45/16 Proxes. The wheels weighed about 13 lbs (16x8). ABS rarely kicked in unless I jsut slammed the brake pedal in a panic stop. I could ususlally hold to pedal to the point of incipient lockup and not get into the bas resulting in shorter stopping distances.

Since I have only 70 miles on these tires, I will have to see if I cna do that.

BTW: it is important to bed in the brakes per the Subaru manual. My brakes became much better after I did that.

We just got hammered with snow in Fargo the other day, about 6 inches to a foot in some places. I just put Dunlop Sport 5000 Asyms on last Friday and I'm very pleased with them. However, ice still makes the ABS go crazy so I grabbed the manual, found the ABS solenoid fuse on the interior panel and pulled it yesterday. Much better! I find I can stop faster in powder and packed snow and I have a little more imput on ice. At least I can feel what is going on unlike the ABS trying to fight me. Don't get me wrong, I like ABS and it has saved my arse a few times and I'll definately re-enable it in the spring when it gets wet and sloshy. But driving on gravel, snow, and ice is better without. The down side is that bright little yellow ABS light bugs me ;) Might have to put some tape over it. I'm thinking about getting a stock Subaru switch and making a On/Off switch that will go next to the Fog and Cruise switch.

Lastly, the snow just makes me happy with my choice to get a WRX over any RWD performance car. Time to put the RWD cars in the garage and leave them till spring guys! This is a true all year all weather performance car. Also, I watched about a dozen FWD and RWD cars get stuck pulling into a parking lot yesterday, so I purposely drove over to the same spot and I couldn't get myself stuck in my WRX if I tried!!! Hahahaha

Mike :D

just an fyi here. my abs was triggering prematurely as well when hitting bumps w/ a light application of the brakes.

i got under the car and found out that the abs sensor was almost ready to fall off the driver's front hub. the single bolt that fastens the abs sensor bracket to the hub had backed out about 75%. this explained why the abs was triggering when hitting a bump (the sensor goes momentarily airborne and exceeds its sensing range and the ecu can't detect the wheel and thinks the wheel's locking up => abs activates).

i put some high temp loctite on the bolt and snugged'er back up. no abs problems anymore. this only happened on one side. i removed the other front hub's sensor bracket bolt and did the same fix... there is no evidence that FHI provided a locking feature on the bolt, thus, it vib'ed loose.

duckboy

I'll check my sensors when I get home and I'll let you know what I find.

Originally posted by duckboy
just and fyi here. my abs was triggering prematurely as well when hitting bumps w/ a light application of the brakes.

i got under the car and found out that the abs sensor was almost ready to fall off the driver's front hub. the single bolt that fastens the abs sensor bracket to the hub had backed out about 75%. this explained why the abs was triggering when hitting a bump (the sensor goes momentarily airborne and exceeds its sensing range and the ecu can't detect the wheel and thinks the wheel's locking up => abs activates).

i put some high temp loctite and the snugged'er back up. no abs problems anymore. this only happened on one side. i removed the other front hub's sensor bracker bolt and did the same fix...

duckboy :eek: Verrrrrry interesting!

Wow, finally a cause effect relationship to explain this, I've seen such symptoms on rare occasion, but not since a recent service, perhaps a similar thing was dealt with.

Nice to see somebody actually got a quantified fix for it!

All I can say if it does it again with my WRX I am pulling the fuse. It is too scarry and real! My wifes Legacy GT does not do it. I wonder if it has to do with the stiff springs etc. of the WRX

did you all find that you had a similar problem with your abs bracket falling off? has your abs premature triggering has gone away? let me know. i'd like to know if i should be expecting some serious might occur with my abs.

duckboy

I just gave it a quick look so far. It 'feels' tight. My Grand Prix Pontiac is burning coolant, so it's taking the WRX's spot in the garage right now for a tear-down. It's too cold/rainy to work on the Subie outside. But I should have the engine put back together next week, and I'll be able to take a closer look at the sensor.

I've got to take the car into the dealership tonight for driver's side window repair (third time) and I am going to talk about this specifically. I can replicate this at any time on one specific turn lane that has a deep manhole that is offset to the right side. No gravel, nothing. As you brake on it, the ABS DEFINETLY keeps going well after the manhole. It's about 20 feet before the line, and if I brake firmly (not panic) from 35, it will go on and continue all the way across the line. It's definetly something with one wheel abs working in a strange fashion. Foot falls to the floor, and abs continues long past where it should. If I stradle the manhole (practicaly have to drive on the curb, but still) I can make the same stop with 3 or more carlengths to spare before the line.

take care,
rob

well im glad im not the only one ... thank you i club for all your dedicated input. i experienced this braking problem many times. it would be a shame on soa not to do a thing about it. n i thought i was crazy n defective alone.

I've had the same thing exactly; last week I almost rear ended a guy on the freeway after braking over bumps and have almost rear ended cars at stop lights after braking over some bumps at least 3 times now.

This happens with RE92s and 17" S-02s on the car.

I reported it to SOA (not knowing about this thread) and they recommended I take the car to the dealer, well of course the car got the all clear at the dealership (i know my brakes are good!)

I called SOA back and am awaiting a call from the person handling my case, with the knowledge of this thread and the exact same scenario happening to others I'll see what we can get SOA to do.

It's funny because this thread is such a revelation to me, how amazing it is that we all have the same story to tell.

I am not alone!

I'll keep all informed as things progress (if I can get SOA to do something.)

- Richard.

I still haven't been able to duplicate the problem, though I recall this very same thing that you all describe happening in my Legacy GT, with the stock tires. I was also (not that I am suggesting that anyone else might have been) coming up to the stop and stopped cars too hot (fast, that is).

I got on the brakes, and hit a frost heave. The car did indeed take longer to stop. Of course, when I installed the DMS/P1/Dunlop 9000 combo, I never again experienced the problem on that car, nor on my WRX with the same suspension package.

I wonder if putting on the DMS immediately, meant that my ABS sensor got tightened to spec, in light of another member's discovery about his ABS bracket? Or if it's just a car to car thing?

Kevin

Originally posted by Bugsie1
I've had the same thing exactly; last week I almost rear ended a guy on the freeway after braking over bumps and have almost rear ended cars at stop lights after braking over some bumps at least 3 times now.

This happens with RE92s and 17" S-02s on the car.

I reported it to SOA (not knowing about this thread) and they recommended I take the car to the dealer, well of course the car got the all clear at the dealership (i know my brakes are good!)

I called SOA back and am awaiting a call from the person handling my case, with the knowledge of this thread and the exact same scenario happening to others I'll see what we can get SOA to do.

It's funny because this thread is such a revelation to me, how amazing it is that we all have the same story to tell.

I am not alone!

I'll keep all informed as things progress (if I can get SOA to do something.)

- Richard.

Nope, you are not alone. My car is at the dealership today to have the interior door panel replaced (power window problem) and I asked the mechanic to just check it out. I described the situation, and he seems competent and friendly enough. He said he would try and duplicate it.

On another note, I called SOA to discuss the problem with me and promptly got the brushoff. They asked me to describe the problem in detail and told me "someone will be calling you very shortly about this." Well, they didn't.

Could you give me a contact number for the person you spoke to? Perhaps if I report it to the same person you did, they might take both of us a little more seriously.

The person dealing with my case is "Karen" (that's all I know.)
My case number is 351927

I encourage everyone who has had this problem to call SOA (1-800-SUBARU3) and report it. Get a case number and log it here in the thread.

Also fill in the form at NHTSA;

http://www.nhtsa.org/cars/problems/ivoq/default.htm

then at least they'll notify SOA and it'll be taken more seriously.

- Richard.

I got the car back from the dealership, and they were unable to replicate the problem. The tech acknowledged on the form, however, that the problem seems specific enough that perhaps a testdrive with a tech should be scheduled. I'm very pleased they are at least willing to try and believe me.

Just on a somewhat unrelated note:

My 99 outback was braking very poorly. In fact, it was barely braking at all. The pedal would touch the firewall and the car would slow down. I could not engage abs on dry or wet roads although it would activate on gravel. I had horrible fade and essentially could complete one 80mph stop within normal distances - any braking after that was non-existant.

Took it to the dealer 3 times, all 3 times they could not reproduce the problem or follow my instructions. They did however leave some scratches on the car and grease on the seats.

They didn't even bleed the brake system.

I finally fixed the issue myself by replacing the front rotors & pads w/ aftermarket and bleeding the brakes with ATE Super Blue fluid. My brakes still aren't as good as I would like, but they do work. I am jealous of those of you who have dealers who care about customer safety and service.

Originally posted by remarcable
Just on a somewhat unrelated note:

My 99 outback was braking very poorly. In fact, it was barely braking at all. The pedal would touch the firewall and the car would slow down. I could not engage abs on dry or wet roads although it would activate on gravel. I had horrible fade and essentially could complete one 80mph stop within normal distances - any braking after that was non-existant.

Took it to the dealer 3 times, all 3 times they could not reproduce the problem or follow my instructions. They did however leave some scratches on the car and grease on the seats.

They didn't even bleed the brake system.

I finally fixed the issue myself by replacing the front rotors & pads w/ aftermarket and bleeding the brakes with ATE Super Blue fluid. My brakes still aren't as good as I would like, but they do work. I am jealous of those of you who have dealers who care about customer safety and service.

You can always call subaru and tell them taht you will file a report with the government.

Back in 1967 (I am probably the oldest WRX driver in the US) I had a Cougar that had out of round wheels. I knew they were out of round because when I put michelin X's on it they weren't round and the tire dealer checked. After a big hassle, I got to see the Mercury factory rep. He looked at it, said "Micehlin tires. Your tires are bad. and started to walk away. I said, "Guess I'll call my lawyer". I got new whells.

Jan

A little update. SOA has been in contact with me multiple times over the past few weeks. They are going to have a regional tech rep meet me, and take a ride in the car with me driving. As you may or may not know, I can replicate this braking problem pretty much at will. They want to log the actions of the ABS computer when this happens, which is by far the most direct acknowledgement of a potential issue. I was told that none of the other owners contacted about this could replicate it on a road near the dealership or were willing to help. Cmon guys, I'm disappointed! Anyway, if anyone else can replicate this, and can do so consistently _on the stock rims and tires with stock suspension_ please email:
shopf@subaru.com (Susan Hopf)

She is handling my case, but is also working with some member of their management staff who is apparently trying to track down this exact problem. Be nice, she has been extremely helpful and patient. They have not once claimed that the problem did not exist, even when a local tech couldn't replicate it when he was driving.
take care,
rob says, "Fight the power? Hell, we ARE the power."

Good job man. Keep us posted!
Strangely enough I haven't had the problem occur in a month or so. Of course, I jinxed myself now. :)

Jeff C.

Great news!

I have plenty of ABS driving experience to know that the WRX pedal just plain feels WRONG during ABS'ing. I was on asphalt ripples on a downhill approach to a red light with cars under it. It was on a dry sunny day last week. I hit the brakes from 35mph as the tires hit the ripples. I was startled. It felt like a brake line let go!!! You know-pedal turns to sponge. The car did not appear to be slowing down!!! I pumped the pedal, got out of ABS and gently stopped it with my heart in my throat. I will try some ABS'ing in the dirt around my area to see if I can duplicate it. If the pedal does go soft, there IS a BIG problem. My 92 Legacy NEVER did this in rain, snow, dirt, leaves, or bumps. The ABS in that car just tickled my foot not my MIND. My 2001 Legacy never plays mean ABS tricks either.:confused:

LETS DUPLICATE THIS FOR A SERVICE DEPARTMENT. Where's Ralph Nader these days?

Originally posted by cygnusz
I have plenty of ABS driving experience to know that the WRX pedal just plain feels WRONG during ABS'ing. I was on asphalt ripples on a downhill approach to a red light with cars under it. It was on a dry sunny day last week. I hit the brakes from 35mph as the tires hit the ripples. I was startled. It felt like a brake line let go!!! You know-pedal turns to sponge. The car did not appear to be slowing down!!! I pumped the pedal, got out of ABS and gently stopped it with my heart in my throat. I will try some ABS'ing in the dirt around my area to see if I can duplicate it. If the pedal does go soft, there IS a BIG problem. My 92 Legacy NEVER did this in rain, snow, dirt, leaves, or bumps. The ABS in that car just tickled my foot not my MIND. My 2001 Legacy never plays mean ABS tricks either.:confused:

LETS DUPLICATE THIS FOR A SERVICE DEPARTMENT. Where's Ralph Nader these days?

I read in EVO magazien (British) that the Posche 911 does the same kind of trick with ABS when the front starts bobbing up and down.

FWIW, I had a similar experience on a bomupy surface when Iw as cut off by soem ignoramous. The next thing I did was get rid of the crap RE-92's and put on Toyo Proxxes T1-s (225-50/16). Now the brakes behave normally. Besides thtaq, the car does not lean antything like it used to. Understear has all but disappeared.

I thinkt he sidewalls of the RE-92's are too soft and the flex, loading and unloading the tires and suspension and giving erroneous readings to the ABS.

I would like to hear what experiences other people ahve had, getting rid of the crap OEM tires. (Are you listening, Subaru? You don't need a Ford/Firestone problem).

The next thing I did was get rid of the crap RE-92's and put on Toyo Proxxes T1-s (225-50/16). Now the brakes behave normally.

The brakes were probably behaving normally on the RE92's, you just didn't have as much traction.

Glenn

Originally posted by Glenn Wallace


The brakes were probably behaving normally on the RE92's, you just didn't have as much traction.

Glenn

When I got my 93 RX-7, it came with Yokohama A022A's. Int he damp I couldn't go aroudn a corner any faster than an explorerer. In the raan, it was worse. As soon as I went to Dunlop SP-8000's,the car became drivable int he rain. As I went throught Bridgestone S02's, Sp9000's and the Proxxes (in 8 years and 135,000 miles you get to samplle a lot of tires) the car got progressively better.

Now, I will tell you again, the WRX is a different car onthe Proxxes than it is on the RE-92's. I do not get lockup any sooner than the RX-7. Braking distances are much, much shorter. There is 1/3rd the lean in corners.

I wish some one else would change their tires and convince the rest of you guys (and gals).

I see many of you people spending tons of money on modifications and zilch on tires because they aren't sexy. Yet, they represent the biggest and cheapest perfomance change that you can make. Brembo brakes won't make the car stop any quicker on stock tires.

The tires that come on the car are great for giving demo drives, when you aren't pushing the car. They are soft, smooth, quiet. The Proxxes are hard, not very noisy, and stick liek glue.

I agree that the re92's are poor performing tires, however the WRX ABS system seems to have some anomalies when the brakes are initially applied on a bumpy surface. They seem to work fine if they are applied before hitting bumps. I have been able to easily repeat this braking problem.

No RE92s=no brake issues for me. Once, I thought that I had found the perfect spot to duplicate this issue:

Downhill exit ramp (straight) with a big a** hump about midway down it. On a clear night with no traffic behind (or in front of) me, I tried it. I stood on the brakes as hard as I could just before hitting the hump. The ABS went off, every light (almost) on the dash came on, and the car stopped so fast that I stalled it (oops!). Started it back up, and drove off. No pedal to the floor, no nothing. I should note that I was on 17" P1s with Dunlop 9000s.

I'm sure that some people have defective setups. In a run of thousands of cars, this will indeed happen. And no, I don't think that Subaru has a Firestone/Explorer situation on their hands. The RE92 is a fine tire, driven as Joe or Joan Q. Public would drive it. It's only in the hands of an enthusiast driver that its inadequacies become apparent.

Good luck,

Kevin

Originally posted by Glenn Wallace


The brakes were probably behaving normally on the RE92's, you just didn't have as much traction.

Glenn

Glenn:

That is precisely my point! The RE-92s do not have the traction that a decent tire has. Poorer traction means that the wheels lock sooner, the bas comes on sooner.

I ahve another suspician that I have no way to verify: the extreme flexing of the sidewalls on the RE-92's may make one wheel start locking up, the ABS detects the difference in rotation between the two wheels and activates.

BTW< if you look at road tests of the RX, you will see that braking distances really, really suck.

My daughter's signifigant other has a new civic and hates the tires ebcuase of greasyness in the rain. The manufactuerers of most cars put on terrible tires.

My daughter lives in Boston. She just bought a new Imprese Ouback Sport. It has RE-92's. I think she should replace them

Originally posted by superspd8
[B]

Glenn:

That is precisely my point! The RE-92s do not have the traction that a decent tire has. Poorer traction means that the wheels lock sooner, the bas comes on sooner.


that may be true, but theres something else up with the abs on the new age impreza.. I've had these same problems with abs coming on under non-normal conditions, and the worst part is that 1/2 second of no brakes at all before the abs does anything.. its really some scary S*** .. I have never had any experience in other abs-equipped cars. the rate of oscillation in the subaru brakes is really low also, leading me to beleive that the whole system is cheaply built. I'm seriously considering putting an ABS kill switch in. Tires arent really the primary issue here, since the activation happens on things like pothole and stuff like that, although you are right that a better tire will lock up less hence less abs under hard braking.

GTguy, find a bit pothole like a recessed manhole cover or drain and hit the brakes