I was working with my brother yesterday on his '97 LS and his rear brake pads are noticing some accelerated and uneven wear. We just changed the rear rotors and pads about 6 months ago and their already worn pretty badly again. The front rotors and pads seem to be wearing at a normal rate however. The passenger side rear rotor and pad are worse than the driver side. The outer pad (side closest to wheel hub) on both rear sides seems to be worn more than the inner (side farthest from hub) pad. The rotor on the passenger rear side has been scored pretty badly due to the pad wearing unevenly on the outer pad. The pads are a ceramic compound and the outer pad has been worn down to the metal and the metal portion was scoring the outer edge of the rotor as a result of this. We were going to just get the 1 rotor resurfaced and replace both sets of pads, but we were't able to depress either of the caliper pistons on the passenger or driver side. They seem to be seized up pretty good. I've replaced rear pads on my 95 and his 97 a few times and the piston has never been this hard to turn back into the caliper. Obviously, this is a factor in the pads being worn unevenly. What I'm not sure about is what to do next, or if anyone has had a similar problem on their 94-01 Teg. I'm thinking that since both of the pistons are seized, the calipers on both sides will need to be rebuilt or replaced with new ones. I'm also thinking that there may be an issue with the brake proportioning valve under the hood on the firewall. This would explain the increased rate of pad wear due to the rear brakes being used more than designed. Normally, rear brakes are only biased to about 30% and the front at 70%. Any ideas or help on this would be appreciated! Worse comes to worse, we'll just take it to a brake shop ad have them look at it. I would like to be able to do it ourselves though. Thanks!

 

Since you couldn't depress the pistons on the rears(and I see you said turn, so it's not that you're trying to just push them in like the fronts), I doubt it's the prop. valve or anything other than the calipers themselves. I'd get some rebuilt ones. Might find a good deal online or hit up a local parts place.

If it was just that the pads were potentially sticking, I'd lean towards taking a look at the e-brake mechanism on the calipers (or maybe even the MC/prop. valve) but since it's so uneven and, as said, you couldn't get the pistons to move, I would lean towards the calipers. Not a mechanic but that's my guess.

When was the last time the fluid was bled on the car?

 

Sounds like they're hanging up. All the slides and contact points need to be greased so they move freely. If they bind, you will get this uneven wear.

 

I had a similar issue on my 98. Replaced the rear calipers a few months ago and everything is OK so far. Gas mileage went up a little since the seized right rear caliper is not causing a constant drag. Also, you always replace calipers in pairs (left and right side on the same axel) to ensure even braking.

 

yep, sounds like its a seized caliper.

if its not turning back in, then its either corroded or busted somehow.

 

Have you tried opening the bleeder screw and then pushing the piston back in?

 

hey thats a good idea. but wont that introduce air into the lines?

 

Sometimes, but if you're like me, I always bleed the lines after a brake job anyways. That's the easiest way I have found to see if you have a frozen caliper or just a collapsed line. A collapsed line would also prevent the piston from going back in, kinda acting like a one way valve.