Rear Brakes Wearing Before Front Ones...Interesting!

Nictrix · Post by **Nictrix** » Sat Aug 13, 2016 11:07 pm

Maybe the auto hold on hills make the rears wear quicker than the fronts, or add to it.

ronk · Post by **ronk** » Sat Aug 13, 2016 11:14 pm

Nictrix wrote:Maybe the auto hold on hills make the rears wear quicker than the fronts, or add to it.

No auto hold on mine it's a standard Torque converter auto !

techathy · Post by **techathy** » Sun Aug 14, 2016 10:45 am

I did about 45 miles on a flowing A road without touching the brakes except for stopping at my destination. The front discs were cool to the touch but the back brakes were warm, and there was a thin film of brake does on the rear wheels only.

ronk · Post by **ronk** » Sun Aug 14, 2016 10:52 am

techathy wrote:I did about 45 miles on a flowing A road without touching the brakes except for stopping at my destination. The front discs were cool to the touch but the back brakes were warm, and there was a thin film of brake does on the rear wheels only.

Did you use the cruise control ?

techathy · Post by **techathy** » Sun Aug 14, 2016 11:02 am

Nope, this was flowing A roads with lots of bends doing 45-70mph all controlled with the throttle. Only noticed because the rear wheels were noticeably dull compared to the front wheels.

ric19 · Post by **ric19** » Sun Aug 14, 2016 11:31 am

Well I dont have Cruise Control and its a manual and my pads were changed at 14K, but I hardly ever drive on a Motorway, and its usually on twisty A roads in the Peak District

Andrew J · Post by **Andrew J** » Sun Aug 14, 2016 11:57 am

Thanks for the replies everyone. Seems like it's not just mine then. I wonder if the brake drying thing has something to do with it too?

It's starting to sound like there's a few contributing factors to increased brake wear on the rear brakes.

Oh just for info in-case anyone has one, the guy at the dealer said he'd noticed this on the 5-series as well.

Cheers,

Andrew

GuidoK · Post by **GuidoK** » Sun Aug 14, 2016 12:17 pm

techathy wrote:The front discs were cool to the touch but the back brakes were warm, and there was a thin film of brake does on the rear wheels only.

So then its definately a matter of drag on the rear pads (in your situation at least)

Maybe the rears are also a different compound. to prevent squeal or something.

techathy · Post by **techathy** » Sun Aug 14, 2016 1:02 pm

I'd suggest it's the ediff &/or DSC. Certainly on my 120dx with DSC on stability control & traction control seemed to kick in before the AWD system got to work properly. Turning it off meant that there was a lot more steering correction to be done in a straight line over bumpy roads but in a bend it felt so much better. I've not driven a huge amount with DSC off on the Zed but it could explain the pad wear.

GuidoK · Post by **GuidoK** » Sun Aug 14, 2016 1:23 pm

Did you see the dsc light flicker? I think it isnt active otherwise? (not sure though, there is no real way of monitoring that through obd2 or so)
And dsc also works on the front brakes as well, it would be a huge coincedence that all the corrections (and there would have been a lot for it to get warm) had been made on the rear ones.
But I dont know if you were driving insanely on that stretch or rather normal.
Also strange that on other cars with dsc/dtc (like my car) the rears dont seem to get hot. they have normal wear. I wouldnt know why bmw would take that step back considering that they had that problem in control previously.

And has the e89 active torque vectoring/e-diff at all? I dont think so (bmw says nothing about that I can find). That usually doesnt go through the brakes (as that is not accurate enough to modulate) but through an extra actuated clutch pack. All bmw's with ediffs work that way. I think they call it DPC. First introduced on the x5m/x6m I think.

extaz · Post by **extaz** » Fri Aug 19, 2016 6:53 pm

I too think it must be from the DSC.
My brakes are very dusty. Lots of dust both front and rear wheels and on the rear half of the car. Hard driving causes much more. There must be a lot of DSC braking going on. However my brake wear is normal. I have heard that BMW has tried various brake compounds here in the USA.
I have never checked for elevated temps.

yt851128 · Post by **yt851128** » Fri Sep 02, 2016 10:38 pm

look up "proportioning valve", its connected close to master cylinder, and the technology is neither new, nor is it costly. since a few years ago, almost all the economy sedans, (accord, altima, camry) use it. its not torque vectoring (you wish it is), its not because its RWD, its not cruise control, its not the weight shift during braking, it could be traction control, i think it was limited slip. which is the function you turn off when you get into sport+ mode.

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