tapered brake pad wear
 

i took a look at the front pads today and noticed they are totally tapered. I just bought this car about 2 weeks ago so i'm not sure on the history of the brake job. What could cause the pad to taper so much? its pagid pads by the way.

pads are like this to against the rotors: |\|

maybe previous owner didn't change the rotors when he put new pads in...

well i got the receipt from the old brake job, weird thing is, it says front rotors were machined, and also the rear drum was machined. What drums are they talking about? even the pads says, front pagid pads, and rear drum pads.. I'm gonna stop by the store where he got it done, hopefully they can check it out...

crap, that sucks, they should know better
bmw rotors are too soft to be machined

when you replace pads you have to put new rotors in otherwise uneven wear will be happening on the pads, possible warping of the rotors, etc.

Tapered pads (uneven wear across the pad) are not due to the rotors, they are caused by the caliper not sliding smoothly. It can be the pins (caliper slides) or where the caliper is mounted in the caliper holder. It can also be a problem in the piston (sticking) but that is less likely. What happens is that the caliper does not fully release, and continues to drag.

You can turn BMW rotors, as long as you don't go thinner than the spec. Trouble is, turning them brings them closer to the minimum, and they will wear during the life of the new pads, so even if they are OK when you turn them they can wear out of spec before the pads wear out.

The rear brake shoes are for the parking brake, they consist of a separate drum brake inside the rear rotor. Either that, or the mechanic was totally confused or the work order was written up incorrectly. The rear drum uses shoes, not pads.

Jeff

how do i check the sliders?

They're two pins on the left/right of the caliper in boots. Undo the bolt and a pull the pins out. Buy brake grease from the autoparts store, apply the the pin thoroughly, and slide it back in.

I would do it a little differently. Vin has the location, they are Allen bolts covered by caps on each side of the caliper. However, they are intended to be dry, they shouldn't be greased, IIRC. I would check that the caliper slides easily on the pins, and clean them up as necessary. I would also clean up where the pad ears are, and then grease those points with high temperature caliper grease, as the pads can hang up and cause dragging. If there is excessive wear things can get sideways and cause dragging, or if there is corrosion on the caliper surface where the pads contact, that is what you are looking for.

Good luck.

Jeff, you're right they should be cleaned, but they are definitely meant to be greased. How would they work dry? It's a part that needs to slide freely under a lot of heat. You will actually find products labeled caliper pin grease in autoparts stores, or high temp grease and caliper pins as one of the listed applications.