I know it's kind of long. But I want to make sure I get every thing taking care of before the swap do to this being my DD. I found a set of rear disc on a 82 Trans-Am with a 10 bolt at the local yard. I have been looking for a set of these for awhile for my 89 RS convertible. So I bought the backing plates, calipers and the proportioning valve. Now I have been doing some searching and found that I need to modify the axle housing to get the backing plates to fit. But I also found a couple things here and there that I am not sure about. The first one is that the proportioning valve I got off the 82 won't work with the 89's lines. I looked at both and the lines do look a little larger than the one on the 89. I just need to confirm this. Next is that I need the master cylinder from four wheel disc car, since I was converting it from a drum car. I though I just needed the proportioning valve. So do I need the master cylinder also? Next I heard that I might need the axles from the rear disc car also. Because the rotor might not fit over the flange. Is this true? Or is it only for the PBR rear disc setup. It's starting to seem like it's harder and more parts to do then just put the rear disc on and go. But the good thing is that there is a 86 Firebird there with a 9 bolt with rear disc. I been studying the parts manual and my 87 IROC with the 9 bolt with rear disc. And the rear disc are the same as the 82 Trans-Am. And it looks like from what I saw. Is that I can use the master cylinder and proportioning valve from that 86 Firebird. Since the parts manual said that the 86-87 stuff is the same. And the proportioning valve looks the same on my 87 IROC and 89 RS. Which means the lines should bolt up. So what all this means is, what do I really need to make this work and what kind of surprises am I going to run into. Thanks in advance for all the help!! Adam :-)

 

Anyone?

 

I am going through a similar swap myself. I have a rear from a 82 camaro that i am putting in my 91 vert. From what i have read and have been told, you just need a prop valve and you have to find a way to make the brake lines fit because they are a different size for the 82 prop valve.you dont need a new brake booster, the one you have should work fine. The biggest problem i expect to face is figuring out how to run the brake lines and e-brake line into the rear discs since drums are different. I plan to do this in the next few weeks, if i come across any other problems i will let you know

 

As far as the PBRs, the 88 and earlier, are 10.5" rotors, 89 and later, are 11.75" rotors.

I'd swap entire rears, instead of trying to fit the discs on a drum rear. Besies, the PBR rears will have a posi unit. Certainly not all 10 bolts so. LOTS are open gears.

 

On the early cars,at least '82-'85,you had to order G80 and a V8(if not a Z28 or T/A)to get J65 4 wheel disc brakes.And I don't think you will find factory PBR calipers on 10 bolts before '88.They were cast iron Moraine or Delco-Moraine but the you're right the rotors are 10.5".

The J50 style,most likely what you have now,brake booster will work fine with your swap.There was a TSB in '83 that customers complained of the high pedal effort of 4 wheel disc cars.The solution was to use the J50 booster.But you will need a proportioning valve for a rear disc car(not exactly certain on the master cylinderthough).Also '82-'83 brake lines are SAE and '84 up are metric.And you're right in needing different E-brake lines for your swap.