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Old 04-05-2009, 11:54 PM   #1
evoboy88
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Default Lean Less: The Inside Scoop on Anti-Roll Bars from GRM

So this is an older article I posted up on the svt forums when i was messin around with my svt focus, thought it would be good reading material for anyone that wants a little more knowledge on sway bars!

http://grassrootsmotorsports.com/art...-less/#more-78
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Old 04-05-2009, 11:56 PM   #2
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Update your link......
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Old 04-06-2009, 12:02 AM   #3
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fixed!
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Old 04-06-2009, 06:16 PM   #4
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Good info!

I was just reading a post from TiC about the same concept, regarding reducing understeer.

Most people want to add oversteer to make the car more neutral. Yes, this might make the car more neutral, BUT, you're still understeering just as much. Ideally, we should lessen the understeer. In theory, we can do this by adding a bigger bar in front, to reduce body roll, therefore limiting the amount of negative camber lost, and retaining grip @ the front of the car.

Very interesting idea. Sounds great in theory...but what are the real world results? Are the results as nice from the driver's seat as they are on paper?
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Old 04-06-2009, 06:49 PM   #5
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Quote:
Originally Posted by mowgli29 View Post
Good info!

I was just reading a post from TiC about the same concept, regarding reducing understeer.

Most people want to add oversteer to make the car more neutral. Yes, this might make the car more neutral, BUT, you're still understeering just as much. Ideally, we should lessen the understeer. In theory, we can do this by adding a bigger bar in front, to reduce body roll, therefore limiting the amount of negative camber lost, and retaining grip @ the front of the car.

Very interesting idea. Sounds great in theory...but what are the real world results? Are the results as nice from the driver's seat as they are on paper?

DEAR GOD!!!!! Someone who gets it!!!!

Real world results are just as nice as on paper.

I wrote that months ago, and thought it was dead dead dead.
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Old 04-06-2009, 09:01 PM   #6
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Quote:
Originally Posted by evoboy88 View Post
So this is an older article I posted up on the svt forums when i was messin around with my svt focus, thought it would be good reading material for anyone that wants a little more knowledge on sway bars!

http://grassrootsmotorsports.com/art...-less/#more-78
Quote:
Originally Posted by the article
This is why blindly adding parts to your car may not produce the desired results.
Yes. This

Adding this to the Swaybar FAQ.
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Old 04-06-2009, 09:38 PM   #7
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Quote:
Originally Posted by mowgli29
Most people want to add oversteer to make the car more neutral. Yes, this might make the car more neutral, BUT, you're still understeering just as much. Ideally, we should lessen the understeer. In theory, we can do this by adding a bigger bar in front, to reduce body roll, therefore limiting the amount of negative camber lost, and retaining grip @ the front of the car.
Very interesting.. I just read this article and figured out why a larger rear sway bar helped make my car more "neutral". Before I actually knew what was happening, everything I could think of in my head would equal to more understeer from a larger rear sway bar, but I get it now.

Last edited by chazly413; 04-06-2009 at 09:49 PM.
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Old 04-07-2009, 11:01 AM   #8
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Quote:
Originally Posted by mowgli29 View Post
Good info!

I was just reading a post from TiC about the same concept, regarding reducing understeer.

Most people want to add oversteer to make the car more neutral. Yes, this might make the car more neutral, BUT, you're still understeering just as much.
Not quite - re-read the part about TLLTD.
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Old 04-07-2009, 11:21 AM   #9
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Quote:
Originally Posted by Mind View Post
Not quite - re-read the part about TLLTD.
I assume you're referring to this:

Quote:
As the rate of lateral load transfer increases, additional demands are placed upon the tire. So if we install a firmer anti-roll bar in the front, then we increase the distribution of lateral load transfer toward the front tires. This increases the front TLLTD value, which will result in additional understeer, holding all else constant.
IMO, the key phrase there is, "...holding all else constant."
I have 255's

So, if we have a stock WRX, on which we throw a stiffer front bar in hopes to increase traction/decrease understeer by controlling camber change, it will understeer more, just as conventional thought would tell us.

For this theory pan out correctly, we need to throw some wider rubber under the car to handle the extra lateral load.

EDIT: wait, no...I think I see what you're driving at. re-re-reading.
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Old 04-07-2009, 11:30 AM   #10
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In addition to thinking about just the balance of the car, you should also look at if the swaybar is increasing overall GRIP.

I know swaybars should be used more to fine tune the balance of the car, but on a limited budget they can go a long way to improving available grip.

- Andrew
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Old 04-07-2009, 11:40 AM   #11
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Quote:
Originally Posted by mowgli29 View Post
I assume you're referring to this:



IMO, the key phrase there is, "...holding all else constant."
I have 255's

So, if we have a stock WRX, on which we throw a stiffer front bar in hopes to increase traction/decrease understeer by controlling camber change, it will understeer more, just as conventional thought would tell us.

For this theory pan out correctly, we need to throw some wider rubber under the car to handle the extra lateral load.

EDIT: wait, no...I think I see what you're driving at. re-re-reading.
No, sounds like you've got it - it's all a trade between how much vertical load a tire can take (the wider the tire the more it can take), what your camber is, slip angle, steering angle, etc etc etc. This thread has some conversation and examples regarding weight transfer with some examples... take a look:

http://www.iwsti.com/forums/gd-suspe...nsion-mod.html
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Old 04-07-2009, 12:01 PM   #12
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Ok, Mind...I think I got it...Seems to me like the understeer problem could be attacked from either approach.

Say you're generating X amount of load, which is currently "saturating" the front tires and causing understeer. From here, you need to analyze what the possible causes would be.

Is X load simply too much for the tires?
What if we don't have the best contact patch possible?

If the tires just can't hack it, maybe it's best to run a stiffer rear bar so as to transfer some of the load to the rear tires.
If you need to need to optimize the contact patch of the front tires, maybe it's best to run a stiffer front bar to minimize camber change.

I think I'm just thinking myself stoopid

EDIT: oops, you beat me!
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Old 04-07-2009, 01:45 PM   #13
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Quote:
Originally Posted by mowgli29 View Post
I think I'm just thinking myself stoopid
That means you're on the right path

I think what you described is basically it, you're either losing grip due to camber loss or because there's too much load on the tire (or both). So, it will really depend on your setup as to how you attack the problem. That's probably why people have wildly varying results on this topic.

I think it would be a really interesting question to stock class autocrosses - if the rule was changed to allow a change to either front OR a rear bar, but not both (vs. only allowing changes to front bar only as the rule is today), which bar would they choose?

My guess is RWD would choose front, FWD would choose rear, and AWD would choose...
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Old 04-07-2009, 02:11 PM   #14
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Quote:
Originally Posted by Mind View Post
That means you're on the right path

I think what you described is basically it, you're either losing grip due to camber loss or because there's too much load on the tire (or both). So, it will really depend on your setup as to how you attack the problem. That's probably why people have wildly varying results on this topic.

I think it would be a really interesting question to stock class autocrosses - if the rule was changed to allow a change to either front OR a rear bar, but not both (vs. only allowing changes to front bar only as the rule is today), which bar would they choose?

My guess is RWD would choose front, FWD would choose rear, and AWD would choose...
well said. I'm rather curious myself!

Just to throw more variables into the mix...I'd think people's decisions might also be dependant on which type of suspension a particular vehicle has. For example, those of us with mcstruts all around, versus a fwd car with mcstruts up front and a beam in the rear, double wishbone all around, or mustang solid axle versus cobra IRS....the list goes on
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Old 04-07-2009, 03:05 PM   #15
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between reading that iwsti thread and the grm article, I'm learning alot here, and I thought I knew a decent amount before....

Quote:
But CRITICAL speed of the car - any setup will have a critical speed or moment where you just can't control it anymore. I spun my bone stock WRX plenty of times at autocross (and also plowed into walls of cones).
Never even heard that before...I wish I had read some of this before I oversteered the old Maxima head on into a van! Although, I'm not sure that's what happened...

It seemed like a case of lift-of understeer in addition to the shape/bank of the turn affecting weight transfer...I doubt I'll ever know for sure, but this is certain: I've NEVER experienced a car (and a FWD one at that!) snap oversteer like that before. It was unbelievably dramatic, and at the speed I was going, there was no road left to allow time for correcting.

so after that happening and then seeing this:
http://i214.photobucket.com/albums/c...taccelgain.jpg
I'm getting more and more scared of oversteer (as fun as it can be sometimes)
I think I'll be a little more appreciative of the moderate amounts of understeer on my DD from now on!
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Old 04-07-2009, 03:23 PM   #16
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Well, autocross (especially noob autocross) tends to induce some pretty spectacular conditions on a car. I'm not sure I've ever encountered conditions on the street, or even close to it, that I do in autocross.

But I agree - a snap-oversteer setup is definitely something you want to stay away from for a street car. In my experience, I thought stock setup with a 20mm-ish rear bar was a great balance for the street. But some people think it's too little, and some people even think it's too big .
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Old 04-07-2009, 06:03 PM   #17
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The BIGGEST KEY IDEA to keep in mind is that you have to stiffen the car evenly, stiff c/o's plus stiff bars = nono, at that point, the tires become your suspension, stiff bars with firm to medium spring or stiff springs with a light bar upgrade will produce the best results, keep in mind when springs you are running when you pick a bar setup!!!
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