124 brakes grinding, cant figure it out

[Grdenko]

Hello forum, long time no see.

Heres the deal, about 23k miles ago i got new pads AND rotors (front only), done by an indie shop. The pads i think are OEM type, the rotors are not though, theyre slotted, and rather expensive.

About 5k miles ago i started noticing a strange grinding from the front brakes. The grinding doesnt happen always, but about 1/2 the time under these conditions:
1. seems to be louder when theyre hot, but not necessarily
2. only at low speed, below 15mph, the slower the louder
3. the harder braking, the louder

this, of course caused me some concern so i put 'er up on a jack and took a look at the pads/rotors. Everything looked fine at first, plenty of pad left etc. but after closer inspection heres what i saw:
1. the outer pad was wearing significantly faster than the inner pad
2. the pads were wearing unevenly, more toward the outside edge

i dont know if either of those things is a big deal, but i thought i would note them.

here are my ideas about the grinding, it could be from the slotted rotors, but i never heard this grinding in the first 18k miles on them. or maybe the pads are a different type than i had before?

i dunno, but the noise drives me nuts so im gunna try changing the pads anyway, so id like to get some tips on changing them and what kind to use.

thanks for all of your help.

[Chas H]

The outer pad wear could be caused by sticking slide pins in the caliper.
There may be some notes on changing pads in the DIY section.

[yal]

Sounds like the pads are not seated properly. The caliper could also be binding, if its a 260/300E it has a single piston which pushes against the outer pad, the pushing action causes the other side of the caliper to push against the inner pad simultaneously. The caliper has to be bolted down tightly. I wonder if yours has come loose on one of the bolts.

[Larry Delor]

ATE Powerdiscs? 3 elliptical groves? If so, then that is what you hear with those. Eventually the rotor will wear down, and you won't hear it so much. (obviously)

[Grdenko]

thats exactly the groove pattern i have, Larry. Thats pretty much what i suspected it was, but wanted to be sure. Especially since it didnt make the noise when the rotors/pads were new.

I checked everything else, everything is tight/properly seated. As for the uneven wearing, its minimal and like my buddy said you can hardly expect a 16 year old car to be perfect.

Thanks for the help.

[Stoney]

Take a look at the caliper slide pins for corrosion and pitting as well as the bore of the race they ride in. Try a good lube with a Moly base (green goo) after polishing with an emery cloth and cleaning the bore with a wire plunge brush (or .38 caliber barrel cleaning brush).

I have seen pitting from corrosion and build up in the bore cause uneven pad wear and grinding (example Ford truck (Ranger) calibers are known for this even though most are now a Bosch design/manufacture).

But it also can be the initial wear of the agressively slotted rotors. A quick solution might be to do a pass across the face of the slots with an emery wheel on a
Dremel.

[Grdenko]

Thanks stoney, those are excellent (and cheap) suggestions. Ill do it.