I got a 79 Z28 that ive been working on for a while. New motor, new trans, new rearend. Brakes have never worked well. Always have to bleed em just to get em to work a little bit, But still barely work. I get fluid to all four corners just fine. I replaced one line that had a kink in it. Anyway, What should i verify and definately check before i get a new booster and master cylinder? And i think my master cylinder is leaking anyway. Also, is all of the booster/master cylinders on these cars slanted back real bad? I havent paid alot of attention to others in the past. If i need a new booster/cylinder what bore and such should i be looking for? Rear drum, front disc by the way. Any help is greatly appreciated. This is the major reason i dont drive it much. Thanks

 

Well, if you dont have any major brake upgrades done to the car then I would just go back with a factory booster and master cylinder. Also where is the master cylinder leaking from? If its leaking anywhere below the reservoir then that could be your issue for mushy brakes right there since it would be letting air bubbles in the lines. I would personally check all the lines to make sure they aren't dry rotted or have any cuts or anything like that in them!

 

i really just noticed the leak this past weekend. I mean, it was runnin down and drippin off the frame. Seemed to be leaking out the back of the master cylinder or somewhere close. The brakes are stock right now all around. Eventually doing a complete rebuild. But got another vehicle in that process. I just want the brakes to work, without goin too deep right now. THey just barely work. Ive looked the lines over pretty good in the past. They all seem good. And When i bleed em, i get fluid out of all bleeders fine. Also, i need to replace all the bleeders, cuz they are rounded off. Mods are a 383, afr 180 comp heads, comp hydraulic roller, rpm airgap, BG speed demon, around 10:1 compression. TCI th400 trans. Moser 12 bolt rear, 3.73 gears. Plannin on different motor in future.

 

Ya, I would go ahead and replace the booster and master cylinder together. I'm pretty sure that the issue if you have that much fluid leaking out the back!

 

With leaking at the master cylinder, replacing it is a given, and would also explain where the air is getting in. Don't know if I would mess with the booster yet, I didn't see you mention anything about having a stiff brake pedal. The booster is a power assist, so if you aren't feeling assistance at the pedal, it might be the booster, could also be a vacuum issue. It's up to you if you want to spend the time and money on something that may not be bad.

 

Ya, you may not have to but since you would have it out when doing the MC it would save him a little time and give a little more peace of mind to do it all at once! Plus it shouldn't be that much more for the booster.

 

Pedal never really been stiff. After a good sit for a while.. I get in and the pedal just hits the floor. This is the second motor in the car, Never had good brakes with either motor. I've got the vacuum line hooked direct to the back of the carb, with a "T" halfway to go to branch off to the transmission. Think i may have replaced the check valve once too. Anyone know for sure how to tell which master cylinder to get? Looked at year one and only found this , http://www.yearone.com/serverfiles/p...818AC11899&trk=

Is it at all possible for fluid to leak into the booster? causing it not to work right? seems like i heard this once.
Also i need to replace the bleeder screws. Anyone know what size is stock?

 

You can get a cheap booster in the $80 range. But, 80 bucks in your pocket is still 80 bucks, last time I checked. The power booster will have no effect on the brakes ability to stop the car, only on how much pedal pressure is needed.

 

Ya I feel ya!

 

oh ic. Right now to stop you really gotta lay into em,, But it doesnt seem stiff.. Brake pedal may be on the floor..Even after i bleed em,, they barely do anything. your barely stopping. it just doesnt seem like anything is doing anything. So im assuming i definately need a master cylinder?