Upgraded a 65 mustang from drum brakes to front disc power brakes using a CSRP conversion kit. Kit went on fine, but when the car is turned on there's a good 3" of completely free play in the brake pedal before it gets firm and starts actually braking. If I adjust the pushrod length pretty far out then there's no play, but that causes the brake pedal to be up ridiculously high - much, much higher than the gas pedal and practically in your lap. Even with the current situation, the brake pedal is still a little too high at 3.5" higher than the gas pedal.
When the car is off, there's about 1" of free play in the brake pedal, and then once I turn the car on and the booster is being used, the free play is around 3-3.5".
I've tried the below troubleshooting steps already, which have made zero difference:
When the car is off, there's about 1" of free play in the brake pedal, and then once I turn the car on and the booster is being used, the free play is around 3-3.5".
I've tried the below troubleshooting steps already, which have made zero difference:
- Master cylinder was bench bled
- Brakes have been bled in order several times
- Brake pedal does not "pump up", further indicating that there's no air in the lines
- Rear drum brakes have been adjusted to slightly drag
- Replaced all brake lines with stainless steel and re-bled everything again
- I was thinking maybe I need a 10-PSI residual pressure valve for rear drum brakes, but the site where I bought the kit claims the master cylinder already has an "integral residual pressure valve" of 10-PSI
- I've checked the booster to master cylinder pushrod length with one of these adjustment tools and the rod is dead-on (zero/almost zero gap)
-
- I thought maybe I need a new brake pedal, but I've read that the 65 and 66 Mustangs used the exact same pedal for manual and power brakes, and only in 67 and newer did they use different pedals... This is the only thing I can think of left - something different needs to be done with the pedal, even though supposedly the 65's used the same pedal across manual and power brakes.... I think Mustang Steve's conversion kit comes with a pin that you're meant to weld in around 1" lower on the brake pedal, and a different generic kit I saw includes what looks like a custom pin that you just tighten down after drilling a new hole, instead of welding in:
-
Last edited: