The Stovebolt Site Forums The Shop Area The HiPo Shop Brake booster problem (and a strange one)

I installed a dual-stage power brake unit when my original master cylinder failed on a hill. I bent new hardline to the front, bled the system, and tested. It worked perfectly, stopped the 3.5 ton panel on a dime. I drove the truck to my buddy's shop to replace the sheetmetal damaged in the brake failure, and we ended up doing a major resto. For the better part of a year, it sat in the yard while we worked on a cure for it's cancer.

Here's where it gets strange: When I put it back on the street, I noticed that the brake pedal would stay down when depressed with the brakes locked. I can pull the pedal up and the brakes release, but the only way to make the thing behave normally is to remove the vacuum hose and cap the booster.

So what makes my booster stick with full pressure? I need to get this sorted, as stopping without the booster is a total b1tch.

sounds like you need a return spring on the pedal.
had to do it on my COE as it did the same thing.
go get ya a universal clutch return spring from a parts store..

I would first try just replacing the Vac check valve going into the booster. If that doesn't cure it then you probably developed a tear in the booster seal and just need to replace the booster.

I replaced the return springs for both brake and clutch pedal, but that didn't change anything. I think I'll take it into the local brake shop and have the booster/check valve tested.

I really hate spending money I don't have, and I was hoping this would be something I could solve.

did you put in a proportioning valve too?
Check that the rod isnt sticking.