WATCH: Fixing Brake Knock-Back & Laguna Seca Fail!

MotoIQ Project Infiniti G20 Racecar has been experiencing some braking issues and we try to resolve them before Martin takes it for its first trip to world renowned Laguna Seca! The car has developed a bad case of piston knock-back that has left us with brakes that are less than confidence inspiring. We will start with the basics and work ourselves up to more involved solutions.

Parts used:

StopTech Slotted Rotors
FRONT: 126.42051SL & 126.42051SR
REAR: 126.42055SL & 126.42055SR

G-LOC Brake Pads
FRONT: GP430 – R16 compound
REAR: GP540 – R8 compound

Centric Calipers
FRONT: 141.42075

Wilwood Residual Pressure Valve (4lb.)
4 lbs: 260-15365

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  1. in my car the cause of pad knockback was the check valve in the vacuum hose between the brake booster and the vacuum source went bad. just a suggestion to check yours as the residual pressure valve would fix the knockback issue, but you might still have a bad valve. or maybe its why you still have knockback in some parts of the track

    side question, do residual pressure valves play nice with ABS?

  2. The check valve was actually one of the first things we checked when the issue started, but unfortunately that wasn’t it. Good suggestion though.

    And no idea whether or not the residual pressure valve will work with your ABS system, as our G20 racecar does not have ABS. I don’t see it affecting the activation of the system since that’s usually based on wheel speed alone, but it could affect the actuation of the caliper.

    1. I wish someone would have told me about the check valve when I was trying to solve my knockback issue… I spent lots of money on replacing perfectly good parts trying to track it down

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