[Billfitz]

So at 11,000 miles my pad sensor for the rears trips, which is nuts. I should have gotten four times that mileage out of them. I pulled the right rear wheel, that's the side the rear sensor is on, and the outside pad looked fine. I managed to get a peek at the inside pad, and sure enough it was not even 1/3 the thickness of the outside pad.
After I pulled the pads and the pad carrier it was obvious that there was a lot of rust on the carrier where the pads sat. The inside pad wasn't floating at all, so it was always riding the rotor hard. It took quite a bit of work with an abrasive disc to get all the rust off and allow the new pads to properly slide in the carrier. I don't know if the factory didn't grease the carrier, it sure looked that way, but it's greased now. I haven't done the left side yet, I will ASAP. I'm also going to take a good look at the front pads when I next rotate my tires, in case they didn't get greased as well.

I could have had this done under warranty, but my dealer is an hour and a half away, so doing it myself in two hours saved me three hours of driving. I also don't want the dealer touching the car unless absolutely necessary, as I've done a lot of coding and they have a habit of losing that for you.

Edit 03-24-2018: I did the right rear today, same thing, the outer pad was barely worn, the inner was down to 3mm and rusted in place on the carrier. No indication that the carrier/pad contact points had ever been greased.

[Billfitz]

Part Deux: I changed my front turn signal lamps with LEDs, which is almost impossible without removing the wheels, so I took that opportunity to look at the front pads. The driver's side were fine. The passenger side had the same problem as the rear, the inner pad was half the thickness of the outer pad, so obviously it was not retracting, the same as with the rear. It's a good thing I checked this out, as the wear sensor in the front is on the driver's side, so I wouldn't have known that the passenger side was bad until there was metal to metal contact.
When I worked in a dealer garage 40 years ago the mechanics there always put their new cars up on the lift and pulled their brand new pads to coat the pad carriers and pad surfaces with anti-seize so they would never see this happen on their cars the way they did on those they fixed every day. I guess it's still a good idea.

[F32Fleet]

Thanks for the headsup

[jgoens]

Interesting. I got the brake system warning and idrive says to replace rear pads. They were replaced at dealer under warranty 20k miles ago. I looked through the wheel and the pads don't look that low. I will take the wheel off tomorrow and look at the inner pad.

[lens]

Originally Posted by jgoens

Interesting. I got the brake system warning and idrive says to replace rear pads. They were replaced at dealer under warranty 20k miles ago. I looked through the wheel and the pads don't look that low. I will take the wheel off tomorrow and look at the inner pad.

Normally the system is 99% correct, if you use cruise control alot, it uses the rear pads to brake so thats what causes the rear pads to wear faster.

[jgoens]

Originally Posted by chaungo

Normally the system is 99% correct, if you use cruise control alot, it uses the rear pads to brake so thats what causes the rear pads to wear faster.

I never use cruise control--just strikes me odd that the rear would wear out already and I am still on original fronts which look the same as the rear as far as outers look.

[Billfitz]

Originally Posted by chaungo

cruise control ...uses the rear pads to brake

I don't think that's the case. After changing my front pads to a harder set I noticed the brakes have a different feel than before. That feel is the same whether I brake myself or the cruise does it. I also use cruise a lot, and when I'm slowing coming down a hill to an intersection or on an off-ramp I use the cruise thumb wheel to reduce the cruise speed and let the car do the braking until I get to less than 30 MPH, then I'll put my foot on the brake and take over the braking. There's no difference in the feel or braking rate when I do so.
If you're looking at pad thickness as an indicator that the rears wear faster that's because the front pads are thicker than the rear pads to begin with.

just strikes me odd that the rear would wear out already and I am still on original fronts which look the same as the rear as far as outers look.

The outer pads are literally only half the story. My front and rear outers looked fine while the inners were toast.

[jgoens]

Billfitz what pads do you recommend for the rear for M-sport. Seems like the options are not so great. I was looking at the Akebono for decent performance and low dust but they apparently don't fit. I don't want more dust than OEM but don't want to sacrifice too much performance for sure.

[Billfitz]

I don't have MSport, so I can't speak from experience. I used stock pads in the rear. I went with a bit harder pad in the front for less dust, as the fronts create far more dust than the rears.

[jgoens]

Originally Posted by Billfitz

I don't have MSport, so I can't speak from experience. I used stock pads in the rear. I went with a bit harder pad in the front for less dust, as the fronts create far more dust than the rears.

I may just go with stock pads as I know what I'm getting. Looked at FCP Euro and they are $98...is that about right? Called the dealer and first he said $200 for the pads and when I told him that was a lot more than online he said $146. These pads are expensive.

And for the sensor he first said $56 and then went to $36. And here I was planning on getting Akebono pads for $60. Didn't realize that shopping for pads for this car was going to be a project.

[Billfitz]

The FCP pad prices look pretty good, and you get a lifetime warranty, so you'll never pay for them again. The sensor price is a bit high, I paid around $18 as I recall, but if you plan on keeping the car long enough to anticipate needing it again FCP is competitive.

[rphz]

Originally Posted by jgoens

Interesting. I got the brake system warning and idrive says to replace rear pads. They were replaced at dealer under warranty 20k miles ago. I looked through the wheel and the pads don't look that low. I will take the wheel off tomorrow and look at the inner pad.

If you track your car or drive it hard a lot where traction control or DSC is interfering, it will add additional wear to the rears. The only way to avoid this is to go DSC off as even in Sport+ (DTC active) the rear brakes will engage during slip or loss of traction.