Rear Disc Brakes
Applications & Backing Plate Comparison
First, lets look at the different iron caliper setups out there. Below is a spreadsheet that shows the different applications.
There are front wheel drive setups off Cadillacs, Buicks etc that some try to use, but IMO is not worth it. The discs measure about 10.5" on the FWD and 11" on the RWD. The pic below shows the differences between the two backing plates.
The pic above shows the RWD "Large" backing plate that uses a "Large" GM caliper. In '79, GM went to a "Small" backing plate and thus a "Small" caliper. From what I can tell GM used the "Small" backing plate on the Trans Am from '78-'81.
As you can tell in the above pic the T/A backing plate utilizes a "Small" plate.
"Big" & "Small" Caliper Comparison
In the pic below you can see the difference between the "Big" and "Small" calipers.
Caliper Rebuild Instructions
Here are detail instructions on how to rebuild the calipers.
Proportioning Valve
A good starting point for a combination valve is the '79-'81 Pontiac WS6 four wheel disc combination valve. GM still has it available through their parts counters (GM part # 1257189). This combination valve is good, stock-style non-adjustable valve and lists over at www.gmpartsdirect.com for about $80.
'98-'02 F-body Rear Discs
Some other possiblities for rear discs come from the LS1 GM F-bodies ('98-'02). This setup features an integral drum parking brake inside the brake rotor hat that allows a more compact caliper to be used (unlike the previous '89-'97 F-body rear disc setup).
The LS1 rear calipers are similar to the C5 calipers, but with one major difference. The abutment (or caliper bracket to some) is different between the C5 and LS1 caliper. The calipers are very similar and even the abutment interchanges between the two calipers. Only minor cosmetic differences distinguishes the two apart from each other.
Cardone Automotive Products offers loaded remanufactured calipers. Just ask your friendly auto parts counter man for part number 16-4696 & 16-4697 to get the right calipers. Keep in mind that you can possible piece together, with the GM part numbers listed below, the calipers for less money (when you include the the core charge into the picture) than with the parts store sourced calipers.
The '98-'02 F-body rear backing plates (and associated hardware such as the e-brake mechanism) bolts directly onto GM A-bodies featuring the Chevy 10-12 bolt rear ends.
GM part #'s 10444625 & 10444626 will get you the right backing plate & e-brake mechanism for the RH and LH sides.
| GM Part # |
Quantity |
Description |
| 12455127 |
1 |
LH LS1 PBR Caliper* |
| 12455128 |
1 |
RH LS1 PBR Caliper* |
| 12456459 |
2 |
Caliper Abutment |
| 22163484 |
2 |
Flex Hoses w/Banjo Bolt |
| 12530697 |
4 |
Caliper Guide Pins |
| 10289539 |
1 |
LH E-brake Bracket** |
| 10289540 |
1 |
RH E-brake Bracket** |
* - Anti-rattle clips are necessary & can be found through AutoZone (Brakeware part #: H5927).
** - TBD if these fit '64-'72 GM A-body differential lower control arm mounting brackets.
With the above mentioned part numbers, you'll also need to procure rear rotors for '98-'02 F-bodies (Aimco part #: 55050) & brake pads for the same year F-bodies as well.
'98+ 2WD S10
And yet another option is the two wheel drive S-10 setup. It too features a integral drum e-brake setup, like the LS1/C5 setup, but uses a smaller rotor. This setup should fit easily underneith 15" GM rally wheels (unlike the LS1/C5 rear disc setup), but some experimention is necessary to confirm this. More info to follow soon.
Below are pics of the setup!
Links!
GM RWD Rear Disc Brake Page
Another GM RWD Rear Disc Brake Page
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Some other possiblities for rear discs come from the LS1 GM F-bodies ('98-'02). This setup features an integral drum parking brake inside the brake rotor hat that allows a more compact caliper to be used (unlike the previous '89-'97 F-body rear disc setup).
