This is a long time issue. Car was put on hold with the birth of my daughter and am now getting back at it. Im 1/3 of the way into a T56 swap and am wanting to tackle this brake issue shortly after. Im at a loss as I cant figure out whats happening. Had lots of great suggestions from board members but cant get it done. Heres a copy from a old old post. Again I appreciate any help/suggestions.


Heres a quick run down of braking issues with my 91 Z28 1LE 355 .
Car has horrible braking. Cannot for the life of me come anywhere close to locking up my brakes even if I two foot her. The pedal isnt spongie or soft. It feels like it used to when I could lock up the brakes. However, the pedal goes hard after 3-4 rapid pumps. It feels like there is no vacuum left in the booster. Has lower vacuum due to the cam. Heres what I have done so far with no real improvement

1) Added EARLS stainless braided flex lines
2) Tried a vacuum resevoir
3) Replaced can with SSBC vacuum pump so no low vacuum issues
4) Flushed and bled and bled and bled fluid
5) Verified visually the calipers are moving and not binding
6) Changed rear calipers , pads and rotors
7) Cahnged brake master cylinder
8) changed booster check valve
9) changed front calipers, pands and rotors

Ive got a new combination valve to go in. Im now ready to just bite the bullet and buy a new brake booster. I am concerned about quality of boosters. Does anyone have any experience or recommendations on boosters? OEM vs. aftermarket? Is it possible to rebuild them?
Thanks in advance.
Kris

 

I'm going to bump this. I have similar issues with my 87.

 

Describe your vacuum plumbing, and have you vacuum tested the booster?

 

I have only done the "pump the pedal until its hard and then start the car and the pedal sinks" test. Plumbing wise I have tried the hose from intake plenum to booster check valve and now I have it plubed from the electric pump to booster.

 

I just put a hydroboost on mine from a astro van. Brake pedal feels good, high and a little firm.

 

What year Astro van did that hydroboost come off?

 

I dont know the exact year. I know I got one that extends strait out from the firewall, not up at an angle. The newer front clip models with the curved headlights have the kind that come up at an angle, the older square headlight models come strait out and had the required flat bracket.