Gbody brake Guru's needed

[nawlins-tim]

It'll be '78/'79 (vender depending) to '81 then '82 to '88 on the boosters. This is because of the change in the master cylinder to match the change with the calipers. The master cylinders will be iron for '81 & earlier, aluminum for '82 & newer.

Well we might be getting somewhere. I have an aluminum master cylinder but it seems straight bore. I have to take a closer look on that. I read that the early master will fit on early AND late booster. But not the other way around. ( later master wont fit the early booster) I bought a early booster and used my old master cylinder, which is aluminum. Its gonna take a real close look to compare the boosters. Good thing I still have the old one

 

[64nailhead]

I’d guess you have the wrong pin installed in the booster or the booster has an issue. There is a chance that the master is not returning fully - easy to check by pulling it off to see if the piston is against the snap ring retainer.

The old style master cylinder can be used with the newer booster without any issues - done that.

 

[nawlins-tim]

I’d guess you have the wrong pin installed in the booster or the booster has an issue. There is a chance that the master is not returning fully - easy to check by pulling it off to see if the piston is against the snap ring retainer.

The old style master cylinder can be used with the newer booster without any issues - done that.

The New booster came with a pin installed. Im sure of that cuz I measured and referenced it to the old booster pin. Might be the Master cylinder since its the one that has been on the car for years.

 

[nawlins-tim]

***UPDATE***
i pulled it all apart inspected the master cylinder. Nothing odd with it, the dimpled plate at the rear was in the correct position. next I removed the the Booster. This time I measured the thing in every way I could and There was no visible differences between the old and the new. i even re-installed the old booster and of course it put the pedal right where it should be. Im guessing there is something missing inside the booster of a spring is cocked or whatever. The first booster was a New piece from Rockauto so I have to box it up and reship it back. I was trying to save a few bucks by useing rock auto. I ended up going to O'Reilly's auto and got a Reman unit for almost 50% MORE. So Im going to have another go at it today. Stay tuned............ By the way, comparing the Rockauto unit with the Oreilly unit is a f'n complete match except the Rockauto one is powder coated black.