CBS and Brake Pad Thickness

Brad from the OC · 05-24-2012, 04:49 PM

I just changed my OEM brake pads on my front and rear on my 06 352i. This is my first brake pad and sensor change. I have 47K miles and the CBS indicated 16K for the fronts and 19K for the rears. When I removed the pads, the fronts had about 75% of life left and the rears had about 20%.

It seems to me that the CBS brake pad life estimate was correct for the rear and way off for the front. I was surprised to see the rear pads worn much more than the fronts. Is this normal from other owner's experience.

I installed Cool Carbons and kept the OEM rotors as they were well within thickness tolerances. Installation went smooth and installing new sensors added to the time to do the job. I had to remove the rear wheel well liner to access the sensor plug junction box.

Reset my CBS and it now says 50K. Based on my first 47K miles, I'm not sure if the 50K is close. Cool Carbons might wear at a different rate than OEM. I'm sure the CBS doesn't know what brand and type of pads were installed. I don't remember what the CBS indicated for brake pad life when the car was new. I thought I read somewhere that it was 60K, but then again I would think that all E90s don't have the same pads and rotors.

Brad from the OC · 05-24-2012, 04:54 PM

Correction I have an 06 325i. I hope that I didn't transpose installing the rear pads on the front or install the outer pads where the inner pads are supposed to be.

Really?! · 05-26-2012, 01:20 PM

Well to answer the first part, yes the mileage and wear for that vehicle is plausible given the mileage. Sure the pads could wear faster or last longer given types of driving and style. My 08 328 has 49k and the front pads are at 6mm and haven't been replaced (new pads are around 11mm). The rears were replace when CBS recommended them to be replaced with 4mm left around 45k. So not too far off from where you were at.
As far as the CBS data the vehicle will calculate the recommended service from the mileage but it will take priority with the feed back from the sensor. The sensor as it wears down will update the CBS data. If for some reason the brake pads vaporized after just a short distance or the sensor was to come loose off the pad and break it would recommend service.
So in short don't worry it will be fine. Just make sure the sensor wire is secured to the bleed valve on the caliper. A common mistake (just thought I toss that in too, please take no offense just a good tip) without it being held it can rub the wheel and rub the wire bare causing the sensor to detect that the sensor has worn to its minimum thickness causing the CBS day to recommend brakes when they are not due.

Really?! · 05-26-2012, 01:25 PM

The second post mentioned mounting pads backward or front to rear. The inners have metal clips to lock into the caliper piston, so that would be hard to mix up. And front to rear the the rear pads are much smaller. So mixing them would be pretty hard. Sorry if that wasn't what you were asking.
Just re read the second post. That was a joke you were making, my bad.

05-24-2012, 04:49 PM	#1
Brad from the OC Private First Class 15 Rep 153 Posts Drives: 325Ia Alpine White Join Date: May 2006 Location: Southern California iTrader: (0)	CBS and Brake Pad Thickness I just changed my OEM brake pads on my front and rear on my 06 352i. This is my first brake pad and sensor change. I have 47K miles and the CBS indicated 16K for the fronts and 19K for the rears. When I removed the pads, the fronts had about 75% of life left and the rears had about 20%. It seems to me that the CBS brake pad life estimate was correct for the rear and way off for the front. I was surprised to see the rear pads worn much more than the fronts. Is this normal from other owner's experience. I installed Cool Carbons and kept the OEM rotors as they were well within thickness tolerances. Installation went smooth and installing new sensors added to the time to do the job. I had to remove the rear wheel well liner to access the sensor plug junction box. Reset my CBS and it now says 50K. Based on my first 47K miles, I'm not sure if the 50K is close. Cool Carbons might wear at a different rate than OEM. I'm sure the CBS doesn't know what brand and type of pads were installed. I don't remember what the CBS indicated for brake pad life when the car was new. I thought I read somewhere that it was 60K, but then again I would think that all E90s don't have the same pads and rotors.
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05-24-2012, 04:54 PM	#2
Brad from the OC Private First Class 15 Rep 153 Posts Drives: 325Ia Alpine White Join Date: May 2006 Location: Southern California iTrader: (0)	Correction I have an 06 325i. I hope that I didn't transpose installing the rear pads on the front or install the outer pads where the inner pads are supposed to be.
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05-26-2012, 01:20 PM	#3
Really?! New Member 0 Rep 4 Posts Drives: 08 E90 N52 Join Date: May 2012 Location: Orlando iTrader: (0)	Well to answer the first part, yes the mileage and wear for that vehicle is plausible given the mileage. Sure the pads could wear faster or last longer given types of driving and style. My 08 328 has 49k and the front pads are at 6mm and haven't been replaced (new pads are around 11mm). The rears were replace when CBS recommended them to be replaced with 4mm left around 45k. So not too far off from where you were at. As far as the CBS data the vehicle will calculate the recommended service from the mileage but it will take priority with the feed back from the sensor. The sensor as it wears down will update the CBS data. If for some reason the brake pads vaporized after just a short distance or the sensor was to come loose off the pad and break it would recommend service. So in short don't worry it will be fine. Just make sure the sensor wire is secured to the bleed valve on the caliper. A common mistake (just thought I toss that in too, please take no offense just a good tip) without it being held it can rub the wheel and rub the wire bare causing the sensor to detect that the sensor has worn to its minimum thickness causing the CBS day to recommend brakes when they are not due.
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05-26-2012, 01:25 PM	#4
Really?! New Member 0 Rep 4 Posts Drives: 08 E90 N52 Join Date: May 2012 Location: Orlando iTrader: (0)	The second post mentioned mounting pads backward or front to rear. The inners have metal clips to lock into the caliper piston, so that would be hard to mix up. And front to rear the the rear pads are much smaller. So mixing them would be pretty hard. Sorry if that wasn't what you were asking. Just re read the second post. That was a joke you were making, my bad.
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