When left-foot braking, if you overlap the throttle and brake too much, the brake booster cuts out. Does anyone know a way to defeat/trick the brake booster into working while left foot braking?

BTW, my car is an 05 2.5 RS Sedan.

<nelson laugh>
HA HA! Drive by wire is smrAt3r than you!

http://www.funkyfridge.com/shop/images/AB-BP-24818.jpg

You'll need a vacuum pump ;)

You'll need a vacuum pump ;)

Care to explain what exactly I need to do?

You need to provide a source of vacuum to the booster that doesn't go away when you press the accelerator.

or just plug the vaccum line and run no power assist. Its at least consistent that way, and you can beef up your leg muscles since you have to brake like a man. If you want power assist in a turbo car, run a vaccum pump, but it just saps power. Just run no vaccum and if you really have a hard time with it, (which you shouldn't, I run cars like this all the time, it takes 5 minutes and is non destructive), you can modify the fulcrum on the pdeal to give you a bit more leverage. Or else spend huge and get a different master cylinder etc.

Okay, that sounds like a good budget option. I don't mind the increased pedal pressure as much as the inconsistency.

Which vacuum line am I plugging?

From the "hot rod" world :

Under $100 at Summit Racing, and should SAFELY solve the issue (http://store.summitracing.com/partdetail.asp?autofilter=1&part=CCA%2D5200&N=115&autoview=sku)

From the "hot rod" world :

Under $100 at Summit Racing, and should SAFELY solve the issue (http://store.summitracing.com/partdetail.asp?autofilter=1&part=CCA%2D5200&N=115&autoview=sku)

Cool, does anyone know if this is STS legal?

I hightly doubt its STS legal. Very highly doubt it.

plug the line coming from the intake manifold to the brake booster. just a big bolt, on the manifold side. IMHO this is MUCH MUCH safer than just a big reservoir (see the link) since that will eventually run out with LFB...

To whomever thinks it is unsafe, well, you stil have the same braking, just without power assist. You can lock up the brakes , so the only safety issue is driver fatigue / brain fade, really. Here are tons of vids of a no assist pedal in action:

http://www.rocketrally.com/managed/mod-CMpro-listpages-subid-41.phtml
-Pat

I hightly doubt its STS legal. Very highly doubt it.

What about just blocking the vacuum line? can you pass tech with no power brake assist?

Sure you can pass inspection. You will have to check out the effects of modifying that.

or just plug the vaccum line and run no power assist. Its at least consistent that way, and you can beef up your leg muscles since you have to brake like a man. If you want power assist in a turbo car, run a vaccum pump, but it just saps power. Just run no vaccum and if you really have a hard time with it, (which you shouldn't, I run cars like this all the time, it takes 5 minutes and is non destructive), you can modify the fulcrum on the pdeal to give you a bit more leverage. Or else spend huge and get a different master cylinder etc.


Have you ever tried braking with NO power assist ??? it is F- ing hard I ran out of gas once and as I coasted into the gas station I was mashing the brakes as hard as I could and I could barely stop the car. So Id say running no power assist is like shooting yourself in the foot.

plug the line coming from the intake manifold to the brake booster. just a big bolt, on the manifold side. IMHO this is MUCH MUCH safer than just a big reservoir (see the link) since that will eventually run out with LFB...

To whomever thinks it is unsafe, well, you stil have the same braking, just without power assist. You can lock up the brakes , so the only safety issue is driver fatigue / brain fade, really. Here are tons of vids of a no assist pedal in action:

http://www.rocketrally.com/managed/mod-CMpro-listpages-subid-41.phtml
-Pat


Maybe its different is if your engine isn't stopped or maybe my opinion is different because I was driving a trailblazer at the time.

Have you ever tried braking with NO power assist

yes, in fact, in every single turbo rally car I have ever driven (and my street cars, and any other turbo car you plan to left foot brake). CLICK THE LINK

Its not hard, you just weren't ready for the pedal effort. Like I said, you can try a bigger reservoir, but once you run out... watch out.

Have you ever tried braking with NO power assist ??? it is F- ing hard I ran out of gas once and as I coasted into the gas station I was mashing the brakes as hard as I could and I could barely stop the car. So Id say running no power assist is like shooting yourself in the foot.
Do you realize who you are talking to here?

Take his advice, shutup, and do it ;) If its good enough for Pat, its DEFINETLY good enough for you.

-Tom

Thanks Pat. I'll take a look at plugging that vacuum line tonight. Like I said, I don't mind the extra effort, it's the lack of consistency that bugs me. I still want the vacuum assist for the street, so hopefully its something I can switch back and forth at the event.

There is a VERY large diffrence between trying to brake a freakin lame Trailblazer with no power assist (unexpected) and racing a Subaru with no power assist (expected).

Dealing with unassisted Scooby brakes is no problem once you have practiced a bit. Pull the vac line off your brake booster (big black cylinder on firewall near windshield washer tank) and plug it with a bolt wound into the hose end. Then expiriment gently with the differing brake pedal feel you will get. Don't worry, the brakes will feel feeble at first, but you can push hard enough with an unassisted foot (left or right, your preference) to stop just fine. The brake pedal mod mentioned earlier will help, but is NOT RECOMMENDED if you are not mechanically inclined or a basic DIY dodo.

WARNING: Any previous advice is not factory approved, may void SOA factory warranty, may result in you smacking into dangerous unyielding upright objects if you do not take into account difference in brake feel, may result in sharply decreased autoX/rallyX times if you actually have a clue, and will change the way you look at your stock brakes, etc etc etc.

When you run unassisted brakes, you soon learn that when you want to BRAKE, you poosh hard. Stupid no-brainer lockup is not easy to achieve. Simple--call it Darwinian ABS.

Dave G
Still Alive Despite Bolt In Rally Car Brake Booster Hose

Haha! I love the disclaimer.

I've run four events so far left-foot braking and this has happened every time. It's not a problem pushing the brakes harder (I'm a runner and a swimmer), just a pain in the ass to not know when the assist is going to run out.

If STS legality is an issue, then neither the vacuum cannister nor blocking the vacuum line are legal.

If STS legality is an issue, then neither the vacuum cannister nor blocking the vacuum line are legal.

:(

My parade may just be a couple monkeys walking in the same general direction flinging poo, but you're definitely raining on it.

Sorry about that :(

It'd be Street Prepared Legal (Booster/MC mods allowed there), but not ST or Stock legal.

Sorry about that :(

It'd be Street Prepared Legal (Booster/MC mods allowed there), but not ST or Stock legal.

I may look into an SP class.... I'm getting tired of getting my ass kicked by honda civics. :lol: