Wilwood brakes problem

[j67]

Hi



The drum-drum to disc-drum conversion is done but I feel the braking power is not impressive. The pedal is not really spongious but it is like not having enough foot pressure to stop the car in a panic situation. It is OK but not like I thought. My Firebird 67 doesn't brake faster that my Chevy Venture ...

Here is the setup

- Brake booster/Master cylinder are a disc-drum Firebird 69 rebuilt unit

- Proportioning valve is a new Firebird 76 disc-drum unit

The system is bled correctly. These Wilwood calipers supposedly can be used with the stock system.

Any idea ? Should I replace the MC with a Wilwood MC ? If yes, wich one ?

Thanks

[j67]

I have the 140-2285 Pro-series kit (camaro 67-69) ...

[dustinls1]

the most common problem with power assisted brakes is that the vehicle does not make enough vacuum to operate the booster effectively. The booster needs to see 18" of vacuum to operate properly. I would put a vacuum gauge on a manifold vacuum source and see if you have enough. I would recommend switching to manual if there is not enough vacuum in the motor.

switching to manual will require the use of a 1" bore master cylinder and raising the attachment point of the pushrod on the pedal to the upper hole in the pedal closer to the pivot point. the smaller bore will build pressure easier and the increased pedal ratio will increase your mechanical advantage over the cylinder making it easier for your leg to build the required pressure.

[j67]

I have not checked the vacuum yet but if it is 18" or more, is it possible that this MC doesn't fit at all the calipers in the 140-2285 kit ? I hope to stay with power assisted brakes ...

[dustinls1]

The master cylinder is not likely the problem, anything witha 1" or larger bore(power master cylinders are usually 1.12") will supply the necessary volume and are capable of making the required pressure.