stiff break pedal 1989 pontiac grand prix turbo abs brakes

I believe your master cylinder needs to be replaced.

Sounds like the power booster or the vacuum hose going to the power booster is bad. Hope that helps! Jim

abs system with no vacuum booster.

Of course it has a vacuum booster. Your master cylinder is bolted to it. That's how the assist is developed to allow you to apply the brakes with minimum pedal pressure. Most likely the vacuum line going to is has either broken or come disconnected. The booster does occasionally fail though so it could be that as well.

I thought the same thing, munron, but it looks like we both stand corrected. With ABS there is no power booster listed in either Rockauto.com or Napa cataloging. I work for Napa and did some research into this today. The ABS unit and master cylinder are one unit. Part number 540087 and retails for $1140 plus tax and $114 core charge! It is unavailable. You will need to have the original one rebuilt if that's the problem. Your local Napa store can probably send it out for rebuilding. Or maybe somebody on Ebay has one. If you have hydroboost that may be the culprit. You'll need to have an older GM mechanic look at it. Sorry I couldn't get you a better answer! Hope that helps! Jim

Love learning new things. Thanks for that info. Hopefully a used one can be made to work if that’s even the problem.

Is the car drivable if this thing starts to fail? Im guessing you would lose ABS but would it default to just normal braking or just fail? Also, is this on ALL Grand Prixs or just the McLarens?

There are usually enough safe guards built into modern braking systems to allow them to keep functioning when a component fails. Complete and total brake failure is for the most part a thing of the past, but it can still happen. If the car stops when you put your foot on the brake then I'd say its derivable at least to a very limited degree, but I wouldn't necessarily consider it safe and it should be repaired as soon as possible. This master cylinder/ABS combo would be common to all Grand Prixs. Probably to all Pontiacs across the board, but again I may be wrong.

Power Brake X-Change Inc. in Pittsburgh Pennsylvania can rebuild this assembly. (412) 441-5729 336 Lamont Place Pittsburgh PA 15232 They have been rebuilding quality units for over 45 years. They also rebuild all types of manual and power steering gear boxes, Pumps, Rack & Pinions, Valves and Cylinders.

Power Brake X-Change is still rebuilding a quality ABS unit for the 1989-1991 Grand Prix. This unit was also used in Oldsmobile. Their phone is 412 441-5729 or 1 800 580-5729 Their web site is powerbrakeX-change.com They have been rebuilding for over 45 years and also rebuild all types of steering units. Manaual and power steering gears, pumps, cylinders, valves for anything that moves!!!