Brake Problems/Rear brakes wearing quickly

[CJ]

Ok.. so this spring I put in all 4 corners of PBR Deluxe Pads.. and front Brembo rotors. The rears were fine so I left them. I did a PDE a month later without having my brakes bled. *still haven't bled them* I noticed on the track day I did, by the end of the day, my front brakes were barely dirty, whereas my rears were SOOO filthy. Like blackened. I don't know why this was.. but braking still felt fine.

Now, I just got back from a road trip. And my brake light came on. Really soon for it to come on.. and so I checked my brakes. My fronts seem fine, lots of pad left, but my rears look like they are quite worn, and could be the cause of the brake light coming on in my gauges.

So.. could my severe rear brake wear be caused by the fact I didn't change out the rotors, and they are too rough or something? Or maybe because I didn't bleed my brakes, my bias is all messed up? More pressure out back than up front? Anyone else ever had this happen??
Thanks.

[endonuky]

If these are PBR the same as Repco Axxis etc. I would guess that the rears were defective PBR's in that they actually WORKED, and the front ones were good and did the usual, no dust, no noise, no stopping power.

Just my experience. I had a set of these pads once. Some of the worst pads I ever had. I bedded them in properly and all, did not glaze them, they lasted for quite a while, I slowly realized that they didn't dust because they didn't wear or provide any friction.

Axxis ultimates are totally different, a really decent street pad. Perhaps that's what was on the rear? It is possible you have a brake bias problem, altho I haven't heard of something like this on M3's.

My 2 cents. Phil

[///Manuel]

Do caliper pistons retract fine? How are your dust boots looking?
I'd think it's more of a pad defect tho... I've had some Hawk HPS's do that on me but in the front and actually only one side...

[CJ]

Hmm, I'm also thinking it could be caused by extended use of the ASC function in my car.. my road trip totalled over 12 hours of driving in slippery conditions, plus city snow driving for a few days. Since the brakes come on when ASC comes on,c ould this be part of the problem??

[John H]

I doubt it. Just think of the amount of work you are doing with traction control: slowing down the rear tires and driveline marginally (not the whole weight of the car). This is very little compared to stopping a 3200+ lb car from speed primarily with the front wheels. Traction control also closes an inline throttle body to cut power to the engine, further limiting the amount of work the rear brakes have to do.

Sonuds like you got a brake bias (perhaps from faulty pads) but I would definitely check the dust boots and the pistons to make sure they retract. Another option is to go drive around for a while without using the brakes, then roll to a stop and see if the rear rotors are hot, suggesting the rear brakes are dragging.

Good luck!

- John