Qestion about my 79 Trans Am's rear brakes

So, I have this 1979 Trans Am that I've had for years, and I'm starting to get around to fix all its many issues. One of them is the brakes.

When I first bought the car (back in 2002), everything worked fine. A few years later, one of my rear calipers locked up (yes, REAR caliper, it's a WS6 car ). I ended up going through my brakes and replaced everything. I did all the calipers, rotors, etc. Ever since, the brakes haven't been the same. The fronts work fine, but the rears barely work at all. I have tried replacing the master cylinder, and then the old leaky proportioning valve was replaced with one of those adjustable front-to-rear billet milled ones like Stainless Steel Brake Co makes. Still, the rears just don't work well.

I was thinking of upgrading the rear brake setup. I can't stand the e-brake setup on these anyway, so I want to go with a setup that has an integral parking brake setup inside the rotor. Is there a car or truck out there that has the same bolt spread as my T/A that I can swap the rear brakes from?

I'd imagine 3rd or 4th Gen F-Body would be the best swap-over.

I do have access to a complete rear brake setup off of a 2004 GTO, but since its a IRS car and has a wacky bolt pattern, I figured it wouldn't work. What about a 90's Chevy Blazer? Pseudosport mentioned that to me earlier.

Just go buy one of the very many off-the-shelf disc brake conversions for that 10-bolt axle.

I have two cars with the stock WS6 rear disc setup and they aren't a very good system, They're better than drums but not by enough to justify the headaches that come with them.

Shawn

Many companies have aftermarket brake kits, but they're not cheap. I suppose if you consider the amount of use you'll get out of it and the headaches you'll avoid, it's probably money well spent. http://www.wilwood.com/BrakeKits/BrakeKitLanding2.aspx

In reply to ncjay:

ditch calipers for 3rd gen fronts and get one of those little mechanical caliper e-brake kits. worked for me, the difference between the two calipers, all else equal, was nuts. i have the ws6 rotors/brackets and 3rd gen front calipers on the back of my belair too.

Bumping up this absolutely ancient thread...

A friend offered me a nearly complete rear disc swap from a late 1990's Blazer on the cheap. These have the integral parking brake shoes, which is a better setup than the stock WS6 stuff. Is it worth the trouble to swap it over?

Probably

Your original issue is probably bad reman calipers. Have seen quite a few. The E-brake has to be exercised for the calipers to function correctly and the adjustment feature hangs up or slips.

The '85 system I used on my '91 is similar to the 70's system. Its never been great, but changing the spring in the prop valve helped. You have to fiddle with the adjuster/e-brake to get is close to the rotor, and hold the brake pedal down when applying the hand brake helps.

2nd gen F-bodies have staggered shocks, and consequently staggered calipers. So if you want to use Blazer brakes you need (IIRC) the left (DS) bracket from a 4WD blazer and the right (PS) bracket from a 2WD blazer. Then you end up using two left calipers, since one is behind the axle and one is in front. There is a big write-up about this on the 2nd gen Z28 site. So depending on what your friend has it may be only half of what you need.

I have a complete Blazer setup that I have dummied up on a spare disc brake differential, but haven't installed or driven on it yet. The whole thing bolts up with nothing more than a few washers to space the caliper correctly. From what I understand there is some trick to the parking brake cable, but I haven't gotten that far yet.

On the other hand, my '81 WS6 has the stock rear discs installed, and while the parking brake is fairly crappy, the brakes stop the car fine overall. Have you checked that there isn't some other issue with the brake? Maybe brake lines or the rubber hose between the chassis and the differential?

they used pretty much that exact same setup with minor changes from the late 70's until 97, at which time it was replaced with the far superior setup that was used in the 98-02 cars... 94-96 Caprices used a very similar setup to the 98-02 F bodies, but with a bigger bolt pattern. i think the 90's S series trucks also used the better system, but with the bolt pattern you need. there are probably caliper bore size differences, but i think all the calipers for those applications are interchangeable, so that gives you some tuning options..

also, GM designed in very little rear brake bias on all the cars they built.. i got the LS1 rear brakes that i swapped into my 86 Camaro to work by totally removing the spring in the proportioning valve under the master cylinder and putting a $35 Wilwood adjustable prop valve inline just after it.. this gives full brake pressure to the rears, with the ability to dial it down as needed.

SEADave wrote: Have you checked that there isn't some other issue with the brake? Maybe brake lines or the rubber hose between the chassis and the differential?

I don't remember if I ever followed up with that on the thread, but yes, I figured that out. My stock proportioning valve was a rusted nugget of metal, so I picked up an adjustable one from Summit. After installing it, I couldn't get the rears to do anything.

One day I got fed up and cranked the line pressure all the way to the rear. To my surprise, the fronts worked fine, and the rears started working! Brakes even felt good.

The parking brake has not worked since buying the car. It was not a drivability issue, as the car is an automatic, but MA has been getting stringent on safety inspections on older cars and I want a setup that will actually function.

I also plan on swapping in a different rear end with the S10 setup when I do this. I have access to a drum brake 8.5 10-bolt posi rear from another 1979 Trans Am, so I will not be messing around with my factory WS6 rear. I'm still in the parts gathering stage.