What causes brakes to wear WAY more on one side?

I've never run into this before, but here I am.

I drove my fiance's Audi S6 on Thursday and noticed that the rear brakes were a bit crunchy. (of course, when asked, she did the standard "oh yeah, I've been meaning to tell you about that.)

Anyhow, I had time this weekend, and I've had the pads for about 9 months (I changed the fronts back then, and bought rears just in case. Checked them out and there was still plenty of life in them, so I threw the box on the shelf and waited.)

I got the car jacked up and went to the left hand side first. There was still at least a quarter inch of pad left, and thought that they should be much worse for the amount of grinding I felt.

oh well, I've already got the caliper off, I may as well change them at this point.

Finish up and go over to the right hand side (passenger side). They are down to the backing plates. NO PAD AT ALL. That's more like what I felt!

Here's the results -

LEFT SIDE -

RIGHT SIDE -

Shouldn't they be wearing pretty evenly?

The calipers on this car (1995 C4 Audi S6) have integrated parking brake. Is it possible that the left side parking brake cable is seized or something?

Yep, that is possible. It could be a stuck caliper.

Sliders or pistons probably aren't moving, take it back apart and find out what isn't moving that is supposed to. Also could be that you don't have the parking brake mechanism properly adjusted and functioning, but either requires disassembly.

Bryce

Bad sliders.

Wait, is it one corner wearing fast, or each side has one pad of the pair wearing fast? if its one pad of a pair wearing bad slider, if its one whole caliper wearing you have a stuck adjuster, bad brake hose, or something to that effect causing drag.

+1 for sliders

+2 on sliders. Had the same problem on a Honda I owned in Chicago. Unless they are well lubricated any rust will make them stick, especially if they are getting a winter salt/snow bath.

Doubtful on something this new, but do a bleed procedure on those rears. The bleed won't help, but it might reveal a swollen hose. The inside of brake hoses can swell with fluid (especially if it has been neglected and its damp).

What it does is restrict flow. When you add pressure, it pushes enough fluid through to apply the brakes, but then it collapses and holds pressure in the caliper for a few extra seconds/minutes. You should be able to compare flow on both sides.

Plus, bleeding some old fluid out of the calipers can't hurt

Are these the type that have a manual adjustment screw ?

+100 on sliders. I see this phenomenon way too often, it is lack of clean, lubricated, free moving slides 100% of the time (at least on floating calipers). The slides allow the floating caliper to apply even pressure to both inboard and outboard pads. if the slides can't move, the pads cant apply pressure to the rotor= no friction= excessive wear on the other pad as it tries to pick up the slack.

Wire brush/wheel all surfaces that contact other surfaces and are intended to move against one another , then once they are smooth to the touch, lubricate them with a brake specific grease (low temp greases can liquify at high temps and run onto brake friction surfaces causing you to crash and die).

carbon wrote: +100 on sliders. I see this phenomenon way too often, it is lack of clean, lubricated, free moving slides 100% of the time (at least on floating calipers). The slides allow the floating caliper to apply even pressure to both inboard and outboard pads. if the slides can't move, the pads cant apply pressure to the rotor= no friction= excessive wear on the other pad as it tries to pick up the slack. Wire brush/wheel all surfaces that contact other surfaces and are intended to move against one another , then once they are smooth to the touch, lubricate them with a brake specific grease (low temp greases can liquify at high temps and run onto brake friction surfaces causing you to crash and die).

Okay, you got it wrong. It isn't one pad on each rear, it's both pads on the right rear.

I'm guessing it's one dragging caliper. I'll get it fixed.

yeah it's not sliders with both pads on the same side trashed. if it were one pad down to nothing and one ok i'd yell sliders with the mob.

that caliper is shot, the e-brake is holding it, or the rubber hose is bad.

Fiance with an Audi S6?
Keeper for sure.

(The other guys covered the brake stuff)

I'll put this delicately, but if said fiancee is over say, 600 pounds, it could lead to increased wear on one side of the car.