Pad Kickback and long pedal

Discussion in 'Road Racing Forum' started by ddozier, Jun 11, 2019 at 3:30 PM.

  1. ddozier

    ddozier TMO Intermediate

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    Was at Road America last weekend and had a great time running with nearly perfect weather. I know Road America is known for pad kickback issues if you use the curbs and it was something I have experienced many times at that track as well as at Road Atlanta with my old setup. Both the old and new cars used the PP Front and rear brakes with Carbotech pads and cooling added.

    With the new car I was not sure what to expect but had all the same issues so at least it is consistent across both of my cars. For me Turn 8 and the brake zone at Canada both had to have brake checks to reset the pads. I use all the curb at the apex of 7 and the track out of 7, this is causing the issue as if I go through 7 clean I have a firm pedal at 8. I use the curbs though the kink apex and a little at track out as well. By the way they just reworked the gators at track out of the kink and added about a foot of concrete outside of the gators. The new gators are aggressive and the concrete outside of the gators is down right diabolical to drive on I would not advise getting on either if you can help it.

    I am considering a 2psi residual valve to help reduce the issue but was wondering if anyone else is having the same issues and if they had tried the valves as a remedy.

    I spoke with a few racer friends and they said its 50/50 if it will help or not, the concern is about spindle flex and that may be causing the rotor to deflect and push back the pads, but if the spindle is flexing it has to be combined with the bumps from the gators to cause the long pedal. For me it seems the vibration from the curbing and centrifugal force combined is the likely culprit.

    Any ideas?

    Dave
     
  2. TMSBOSS

    TMSBOSS TMO Addict

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    Been there, done that.

    Have to tap the pedal Before you need brakes to reset.

    Curious to know if the residual valve works for you.
     
  3. neema

    neema TMO Race

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    I'm constantly tapping the pedal to make sure brakes are there. Thought it was normal to overcome knock back.

    Aren't there some caliper designs that include a spring behind the pistons to mitigate this? Track use only--I can imagine they add a bit of drag.
     
  4. TMSBOSS

    TMSBOSS TMO Addict

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    C2 & C3 Corvettes have springs behind the pistons. So it’s not a new concept. First production year for the Discs in the C2’s was 1965.
     
  5. JAJ

    JAJ TMO Addict

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    There is another solution for S550's that has an additional benefit: replace the standard front knuckles with GT350 knuckles with the bolt-in hub. The bolt-in hubs are vastly more rigid than the stub axle. The side benefit is that you can put GT350 front brakes on as well (which limits you to 19" rims), or you can add an aftermarket 380mm kit that'll fit under 18" rims.
     

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