My rear gears were getting louder and louder over the last year, and it was time for an upgrade. I found a used disc axle locally, so I decided to change rear ends.

It looked really clean inside, the wear pattern on the teeth was almost non existant. I decided to go with Hawks HP Plus pads, and some rotors from Summit. I put everything back together, and found that one of the old calipers was leaking from the e-brake seal. So I decided to change both of them out.

Now I am getting a "Brake" light on the dash when I hold down the brake for more than a few seconds. The pedal feels a little softer. In swaps that anyone else had done, have you seen this issue? Or do you think that I need to keep bleeding and might have air in the lines? Thanks for any help in advance.

Here are some pics of the rear. I am very happy with it, it is very smooth. I just need to figure out the brake issue now.

The two things that trigger the brake light are;

1) E-brake (hand brake) is pulled.
2) The brake fluid in the reservoir is low.

Have you checked the fluid level? It may be low, and if the pedal feels soft you may need to bleed it.

OK...There was plenty of fluid, but I bled the rear brakes again and they feel better. The pedal is a little stiffer, and the brake light is gone.

On to question two: On the test drive with the windows down, I heard a chadder. I have another problem. I noticed the old pads on the axle were worn unevenly. If you looked straight down at each pad, it appeared that one side wore down further than the other. I just thought the slide pins were dirty, and the new calipers would fix that.

It appears that this is still the case. The pads flop around a little unless I am on the brakes because the top side of the outer pad touches while the bottom part of it doesn't. Also, the bottom side of the inner pad touches while the top side doesn't With pressure on the brakes, everything tightens up. But if I am not on the brakes, the pads can move around slightly. Has anyone else experienced this? I wouldn't think that both sides of the axle had mouting points that were not parallel to the rotor, but it appears that they are slightly. Any suggestions?

I do know that some gm brake pads have different thickness from factory, either that or you have a piston catching up. I dont know about the pads being loose, sure you got the correct pads?

I have discovered why my pads are loose. I took each rear caliper off one at a time. I slowly stepped on the brakes to get the piston to move. When I let off of the brake, the piston goes back in to where it was. Why are the pistons moving back in? I though that the piston should stay out when the pedal is released.

Anyways, this is my problem. The Pistons retract and do not hold the pad firmly against the rotor. So the pads are free to move around between the rotor and the caliper a little bit. The calipers are both new, picked them up from autozone. They do engage the rear brakes very well when I stand on the pedal. They work so well that I am going to need to upgrade the fronts now.

Have I missed something in my axle swap that would cause this to happen? Or is there any way to adjust the calipers so they don't do this?

Yes:

USE THE PARKING BRAKE. With that old crappy Saginaw system this is THE ONLY WAY that they ever get adjusted. You MUST use the parking brake, EVERY time you park the car; and maybe even twice on Sundays, just for good measure.

To adjust them up right now, you can sit in the car and work the parking brake for about an hour.

It might be possible to take the calipers off and unscrew the piston by hand. But, be VERY CAREFUL about this, though; once you unscrew them too far, it's quite difficult to screw them back in, without the "special tool". In fact, if you actually succeed in getting those to work a little bit for any length of time, that'll be your next problem; because if they work, they'll wear the pad, and you'll have to keep them adjusted by using the parking brake; but when you been adjusting them, and then the pads get thin and wear out and you put new pads in, they won't fit back on over the rotors, so you have to screw the piston back in ANYWAY, just to do a brake job. It's a really terrible system.

Just be glad it's not the one they used to use on the rear of Vettes, back in the 60s and 70s; that's got to be THE WORST ever built. The Saggy setup on these cars is at least not quite as bad as that old one.

Thank you for the reply. I will start working the parking break...!

I have been working the parking brake, and still no fix.

The pads on the drivers side are very loose. It seems like it gets worse after taking the car around a corner. Do I need to keep working the park brake for hours on end to get this to adjust, or could there be another problem? If I have to keep working the parking brake, should I do it with my foot on or off of the brake pedal?

My only other thought was this...I had to pound the old rotor to get it off. Is it possible that the C-clip on the axle was bent enough to allow the axle to move in and out a little too much? It just seems like after cornering, they get loose and noisy like the axle moves around and forces the piston back in.

I don't know enough about the internals of these calipers. How exactly does the park brake adjust the piston out? Is there anything inside that would prevent it from moving back in once it has been adjusted all the way out?

The proportioning valve can also throw the brake light if it senses a leak and it cant hold pressure.

is this rear end a posi? i just got a beefed up rear and i was wondering what to look for in a posi...sorry if im off the subject a little..

Yes, this is a posi.
----------
The brake light issue was fixed after bleeding the brakes, now it just feels like the pads are loose. It is like the piston goes back in on the drivers side rear caliper.

I hate these rear brakes! I should have found another drum rear end or upgraded to the Aluminum PBRs!

Now that I am broke...I replaced the drivers side Caliper again. I have tried working the hand brake over and over and still have problems with the pad retracting. I have a question about working the hand brake to adjust this out...

Should I work the hand brake with my foot on the brake pedal or off of the brake pedal? I have also tried removing the parking brake lever and backing the bolt out. I haven't had positive results from either process so far. Can anyone else provide advice? The sounds of the pads flopping back and forth in the caliper is driving me nuts.