I have a 91 Trans Am convertible with drum rear
brakes........
I want to upgrade to disk brakes......( aluminum calipers )
Swap whole rear for a disk rear....?
Or
Just swap out brakes......??
What is the easiest way....??
Will PBR brakes bolt on.....??
Thank you in advance

 

Aluminum calipers = PBR (same thing)

PBRs won't bolt directly on, but it's not that hard to make the necessary modifications.

IMO it's best/easiest to buy a rear that's already equipped with the brakes you want, since it's ALOT harder to piece them together, especially when you don't know what you're doing to begin with. However, "easier" kinda means just "less difficult"; it's not easy to find a 89-92 disc brake rear just laying around. OTOH it's also not easy to find someone that has one and is willing to bust it up just so you can have all the NICE pieces off of it. By the time you pay somebody to do that, you will have bought the whole rear anyway; and probably paid them a bit extra so they can afford to dispose of the rest of it which is now GARBAGE.

Another option might be to put a 4th gen rear under it. That would require using wheels with the 4th gen offset however.

 

I also have a disk rear from a 88 GTA it has the older
Non aluminum calipers.......
Can they be updated to the aluminum calipers and rotors....??

 

Notice all the links that say "Search" all over the page? Try clicking any of them and enter "rear disc conversion". Literally read any thread that comes up and you'll get the answers you're looking for.

Buy a conversion kit and get it over with, or learn to live with drums.

 

I bolted LS1 rears to a rear that was born with the iron calipers, no modifications necessary. I'm sure your PBRs will bolt up to the 88 rear.

 

Not without aftermarket or 1 year only backing plates.

 

https://www.thirdgen.org/forums/brak...se-search.html

https://www.thirdgen.org/forums/brak...drum-rear.html
https://www.thirdgen.org/forums/brak...rear-disc.html
https://www.thirdgen.org/forums/faq-...iscs-89-a.html
https://www.thirdgen.org/forums/brak...onversion.html
https://www.thirdgen.org/forums/tran...-10-bolts.html
https://www.thirdgen.org/forums/brak...-question.html
https://www.thirdgen.org/forums/brak...sion-kits.html
https://www.thirdgen.org/forums/susp...onversion.html

https://www.thirdgen.org/forums/brak...se-search.html


!!!!!!!!

 

He says he also has a disk rear from an 88. Was telling him I bolted LS1 rears to an 87 rear that had the iron calipers. I know it can't be done to a drum rear.

 

Disc rear from 88 would be a Borg Warner 9-bolt. The only way to bolt PBRs to a 9-bolt is with the backing plates from a 1989 9-bolt, or to use aftermarket copies.

 

Sorry man, I was thinking 10 bolt although that's not what you said. I misinformed you as Drew has clarified.

 

Hi everyone
Ok this is what I have.......
My car is a 1991 Trans Am Convertible with drum brakes.......( 305 TPI Auto )
My donner car is 1988 GTA { 5.7 TPI Auto } ( I stripped it for the digital dash and wiring harness ) it has disk
Rear brakes ..... old style ( I've been told that they are not that good)
Which rear is better to do a rear disk swap..??
Thank you

 

You're kidding. Right?

 

Not kidding......
I want rear disk brakes with aluminum calipers......
Which of the two rears is better for the swap...
In the 91 vert is a drum rear
The parts car (88 GTA) has old style disk brakes
Or neither and I must find a complete rear WITH the aluminum calipers
Thank you

 

Don't know the best way for you to proceed; you obviously have several options. I've got an 4th gen LS1 rear brake set-up available if you decide that is what you want to do. If your interested just get back to me and be sure to include your ZIP code in your reply.

( Brakes are HEAVY so if you are not in the US the shipping expense would be very high.)

 

Your disk rear is a 9 bolt and they only had the pbr's in 89. Find some aftermarket brackets and bolt up the 89-97 disk brakes. Factory brackets are not plentiful because of the 1 year use. Try flynbye.com.

 

your 1 will need too change the mounting brackets on the axle to work with pbrs ,this requires pulling the axle out off housing .Had a 85 10 bolt disc and cast iron disc calipers and converted it to the pbr the one that were on 1989-1992 ,had to replace brackets and sims and e-cables this ie same as 9 bolts .They also sell kits to convert them

 

I have an 87 disc brake 9-bolt and I bought the PBR adapter brackets from flynbye.com. I believe they were $85. Will be installing over the holidays.

Just a note, this is not a "cheap" conversion. I bought most of the parts from RockAuto and I'm in it for almost $700. Be sure to buy the calipers that come with hardware and brackets - I bought Centric rebuilds.