(TIP) Disable brake booster for left-foot braking in Rallycross
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Thread: (TIP) Disable brake booster for left-foot braking in Rallycross

  1. #1

    Default (TIP) Disable brake booster for left-foot braking in Rallycross

    I wanted an easy way to be able to left-foot brake in SCCA rallycross events without sending myself through the windshield, but without permanently modifying or replacing the OEM brake booster. I also wanted something that would enable me to quickly hook the brake booster back up for daily driving. Here is what I came up with for under ten bucks.

    All you will need is:

    3/8" brass hose barb to male pipe fitting
    Brass cap for said hose barb to male pipe fitting
    Small hose clamp 1/4"-7/8" (I used MasterPro hose clamps with removable key from Oreilly Auto [Part # MP6R004V] for a tool-less installation once I arrive at the event)






    Locate your brake booster vacuum line (The only rubber hose coming off your brake booster, typically located under or to the left of your master cylinder)
    Loosen the clamp and pull the hose from the booster (It will "PSHHHHH" don't worry, this is normal, you are just releasing the vacuum from the booster)

    My clamp was a pinch-type clamp. If yours is the same, take that crap off and chuck it in the bin.
    Replace with the shiny new hose clamp you got from your auto parts store! YAY!

    Now, I lock-tited the brass cap onto the pipe fitting to make sure it wouldn't leak. Any thread sealer will do nicely, but isn't entirely necessary. Really this is just me being extra careful.

    Now, say you've just arrived at your rallycross (or autox!) and you want to activate your LEFT-FOOT-BRAKE-ACTION!

    Just remove the brake booster line (and enjoy the PSHHH),



    Cram the barbed brass pipe fitting into the end of the rubber vacuum hose, and secure the hose clamp around it.



    At this point, I zip tie the hose to something to make sure it isn't flopping around while I'm driving. I encourage you to do the same.


    After you finish your rallycross (or autox!), just clip the zip tie, loosen the hose clamp, remove the barbed pipe fitting, reinstall the vacuum hose onto the brake booster, tighten the hose clamp around it, and you're good to go! I keep my barbed pipe fitting in my glove compartment so I never forget it!

    You probably shouldn't drive around all the time with your brake booster disabled, but ultimately that's your call, and your consequences to deal with should something happen.

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  3. #2

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    Huh? You just need experience braking with the left leg to train yourself for how much force is needed.

    Tim.

    '98 VW Jetta TDI - RallyX/DD
    '96 Subaru Impreza - Rally car

  4. #3

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    I'm told it removes inconsistencies in braking force created by the varying vacuum in the brake booster on turbo cars, but IMO it is just more comfortable to left foot brake with the added resistance. I've gotten a lot of similar replies when showing people this quicky-delete, but this is just how I'm comfortable doing it. To each his own I guess.
    Last edited by tdgrim89; 07-01-2014 at 12:17 PM.

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  6. #4
    100 oversquare right
    Join Date
    Jun 2006
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    First off Impressive Mod. I love this sorta thing, cheap and it does the job that is asked.

    and ... I think you are cheating yourself out of learning how to better modulate the brakes under motor sports / racing conditions. I've wanted to mod my car in the opposite direction. I've had a few times in autocross and rallycross where i was brake spooling so much i ran out of vacuum (and thus out of power brakes) . I did not like it.


    But ya .. to each their own, if its makes racing more FUN for you, then why not ? ( i think in the long run this will hurt your ability to improve and become a faster driver ... BUT it has to be about Fun first )

    lets not loose sight that rally / rally cross is a Hobby , something we pursue for fun in our spare time. if this adds fun for you, keep at it.
    Welcome to Rally Addicts anonymous! Hi I'm Alex Rademacher, and i have a Rally problem..... 23 rallies and counting....

  7. #5

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    Quote Originally Posted by tdgrim89 View Post
    I'm told it removes inconsistencies in braking force created by the varying vacuum in the brake booster on turbo cars
    THAT can be true, yes, and not just turbo cars. Some have switched to manual brakes for that reason. Thing is, manual brakes have different sized master cylinders and different pedal leverage so you can get the same force with less effort. You're potentially leaving some braking on the table by simply disabling the booster. But, hey, maybe you have really jacked quads and it doesn't matter. ;-)

    Tim.

    '98 VW Jetta TDI - RallyX/DD
    '96 Subaru Impreza - Rally car

  8. #6

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    Quote Originally Posted by A1337STI View Post
    First off Impressive Mod. I love this sorta thing, cheap and it does the job that is asked.

    and ... I think you are cheating yourself out of learning how to better modulate the brakes under motor sports / racing conditions. I've wanted to mod my car in the opposite direction. I've had a few times in autocross and rallycross where i was brake spooling so much i ran out of vacuum (and thus out of power brakes) . I did not like it.


    But ya .. to each their own, if its makes racing more FUN for you, then why not ? ( i think in the long run this will hurt your ability to improve and become a faster driver ... BUT it has to be about Fun first )

    lets not loose sight that rally / rally cross is a Hobby , something we pursue for fun in our spare time. if this adds fun for you, keep at it.
    For all of my tarmac driving, I have the ABS disabled and keep the brake booster intact, but in place of left foot braking I've been practicing heel-toe shifting and modulating the brakes with the booster intact. I like to practice as many driving techniques as I can to try to develop a better understanding of car handling and build a solid foundation for a style of driving that feels more natural and comfortable to me. For whatever reason, having the greater resistance in the brake pedal feels more comfortable to me for left foot braking.


    Quote Originally Posted by TronDD View Post
    THAT can be true, yes, and not just turbo cars. Some have switched to manual brakes for that reason. Thing is, manual brakes have different sized master cylinders and different pedal leverage so you can get the same force with less effort. You're potentially leaving some braking on the table by simply disabling the booster. But, hey, maybe you have really jacked quads and it doesn't matter. ;-)

    Tim.
    I got the idea of disabling the brake booster (as opposed to upgrading the master cylinder) from the guys at Dirtfish. So I tried it out and found it to be very comfortable, but I liked that I was able to just reattach the brake booster for daily driving. Once I start building another car for daily driving, I might go full on upgrade with the master cylinder on this car, but for now I think I'm pretty comfortable with my current set up.. but then again I'm always trying new stuff, so you never know. haha

  9. #7
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    Interesting thread.
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