Brake issue on 69 camaro

[ddavisart]

Hey Guys, I'm helping a buddy on his 69 camaro and we just finished adding wilwood disc brakes to the front, wilwood 1 1/8 tandem mc, wilwood proportioning valve, and a 10lb residual pressure valve. His car originally had factory discs on the front and drum on the rear, so we just upgraded the front discs for now. The rear still has the factory drums. We went ahead and put on a 11in brake booster in the process also and bleed the system.

When the brake pedal is pumped a few times the pedal starts to have a slow return back up. Almost like it sticks to the floor. It only does this when the engine is running and the booster hisses alot in the process. I'm thinking maybe its just a bad booster out the box. I checked the engine vacuum to the booster and its getting 20hg which is more then the recommendation. The master was bleeded on a bench before install, and all the air seems to be out of the brake lines.

A few other notes
- I can pump the pedal as much as i want with the engine off and it always feels the same (not sure if this is normal with a disc front/ rear drum setup)
- I can feel the pedal get a little easier and drop some when the car is cranked
- The booster sounds very loud and hisses alot with any contact with the brake pedal when engine is running.

Any idea why the brake pedal would be returning so slow and dropping during a few back to back presses? Each press seems to bring it down a little lower, then you have to wait a few seconds for it to recover.

Thanks

[dontlifttoshift]

I don't if your booster is this way, but a lot of boosters use engine vacuum to return. If it is hissing it sounds like it may be leaking vacuum on that side and that would explain the slow return.

It seems like booster replacement may be in order.

[ddavisart]

Thanks Donny, I'm gonna grab another booster sometime this week to try out. It seems like thats the first thing to try