Hi All, my 84 gsl is almost road ready, but the master cylinder and brake booster are shot. I have found master cylinders all over the place, but not boosters. I read that master/boosters from other cars/years will work, but don't know what to get. what will work? I am not looking to do any mods to the car, just bolt something in that will replace the oem parts. thanks in advance for the help.

 

Your booster can be rebuilt . I had mine rebuilt locally . It was basically full of brake fluid .

 

What are your issues? Heavy brake pedal, leakage, no brakes? I have rebuilt my brakes, new calipers and new master and slave but I still need a lot of pressure on the pedal to stop. I'm thinking like you that the booster could be bad.

 

I'm working off memory here, and not in a position to do much searching rn. I recall a thread in this forum where despite a master cylinder replacement and booster rebuild they still had poor breaking. The problem turned out to be that the pushrod from the brake pedal into the booster/ master was not inserted correctly...reversed iirc.

EDIT:

OK, found the post I was thinking of, but it was for a soft brake pedal: The booster has a "reaction" disk in it. If you had the whole assembly apart, maybe you have the same issue as this person.

https://www.rx7club.com/1st-generati.../#post12437745

The 2nd gen thread that helped the guy above, pictures etc.

https://www.rx7club.com/2nd-generati...r-fix-1103221/

 

Thanks to those who have replied to my question. I wish I could answer better, but I am having the car worked on by a mechanic and he says they are gone.

 

I doubt both are blown. If your master is shot it would leak either internally or externally , leaks cause very mushy brakes at all times . external will drain your reservoir and you will be able to visual spot it . A Failed booster will cause hard brakes and or inconsistent brakes. If your master fails INTERNALLY through the rear seal you will get a booster coconut

 

Hard brake pedal indicative of a bad booster turned out to be a vacuum leak. Pump down test with a vacuum pump showed that I just need some vacuum line clamps.

 

+1 he should start by replacing al of his booster hose and clamps . You only need about two feet of booster hose and six clamps . .

Make sure you don't throw out your check valve and to place it in the right direction

 

Thanks again everyone. I found an old thread that mentioned Prior Brakes in Mesquite TX. I contacted them and sent it out on a saturday. Had it back on Thursday.$140. Highly recommend them.

 

What work did you have them perform? Was the booster not holding vacuum?