Brake wear measurement

lockeed · 04-24-2013, 01:52 PM

Just purchased my E90 about 3 weeks ago... Dealer performed a pre delivery inspection and found the rear brake pads to be at 9mm - which they say is well within limits for the car to be certified.

I just put my 19s on last week and my technician (non BMW) noticed that I had aprox 1/16" of rear brake pads left before getting to the warning probe.

I made 1700km since taking possession of the car. Could the rear pads have faded that quickly during very normal driving? Or does it mean that the tech who did the "certified" inspection screw up on his measurement?

jphughan · 04-24-2013, 02:01 PM

Maybe they're not looking at the same pads? It's pretty common for quicker inspections to only check the outer brake pads rather than the inner ones, which don't always wear quite evenly. I'm also not sure what the thickness threshold is for the wear sensor to be tripped. But to answer your question, no 1700 km of normal driving shouldn't have produced any noticeable wear even on the fronts, certainly not the rears. Rear pads should last probably 35-45K road miles, if not more.

ms372 · 04-24-2013, 02:02 PM

go into your iDrive under info, you should find how much is left in your breaks before the warning comes on.

jphughan · 04-24-2013, 02:06 PM

Quote:

Originally Posted by ms372

go into your iDrive under info, you should find how much is left in your breaks before the warning comes on.

That's only an estimate. The wear sensor doesn't provide actual thickness measurements, it's just a wire that runs into the pad material so that eventually it's exposed from wearing enough pad material away, at which point it touches the rotor, which completes an electrical circuit and triggers the pad replacement warning. But until that happens, remaining mileage is just a guess.

FVM3 · 04-24-2013, 02:08 PM

probably different pads. Replace them asap

Mr. ///M3 RD · 04-24-2013, 02:17 PM

Quote:

Originally Posted by lockeed

Just purchased my E90 about 3 weeks ago... Dealer performed a pre delivery inspection and found the rear brake pads to be at 9mm - which they say is well within limits for the car to be certified.

I just put my 19s on last week and my technician (non BMW) noticed that I had aprox 1/16" of rear brake pads left before getting to the warning probe.

I made 1700km since taking possession of the car. Could the rear pads have faded that quickly during very normal driving? Or does it mean that the tech who did the "certified" inspection screw up on his measurement?

If you can I would return to the same place and speak to the Maintenance Department Manager.

You purchased a certified car ... get what you paid for ... insist upon it would be my advice.

Good Luck!

1MOREMOD · 04-24-2013, 02:32 PM

No way would you see that much use in that short of time. 9mm is almost full thickness. Think they start at around 10 and you can run to about 2-3mm before you break the sensor wire.

lockeed · 04-24-2013, 03:08 PM

Weird indeed... I'll inspect the pads myself and see... In the mean time, I've been denied a set of pads from the dealer... (I'm 700km away from them).

1MOREMOD · 04-24-2013, 03:18 PM

That's lame. At least they are cheap. Last time I checked turner has oem rears for 75.

lockeed · 04-24-2013, 03:33 PM

I'll put a listing in the classified section for some rear brake pads!

1MOREMOD · 04-24-2013, 04:04 PM

Quote:

Originally Posted by lockeed

I'll put a listing in the classified section for some rear brake pads!

Try calling cicle bmw in NJ. I've used them for oem parts and usually pretty cheap. Or winslow bmw in denver.

lockeed · 04-24-2013, 04:16 PM

I'm in Quebec - there's gona be a ton of import fees and taxes just on shipping... Not really an option unless the price is ridiculous...

lockeed · 04-24-2013, 09:49 PM

I'm wondering, do I need to replace the brake pad sensor while putting new pads at the rear?

1MOREMOD · 04-24-2013, 10:56 PM

Quote:

Originally Posted by lockeed

I'm wondering, do I need to replace the brake pad sensor while putting new pads at the rear?

no only if it has worn thru which isnt likely.

lockeed · 04-25-2013, 08:08 AM

Thx for the answer

04-24-2013, 01:52 PM	#1
lockeed Second Lieutenant 20 Rep 266 Posts Drives: E90 & E46 M3 E39 M5 E36 325is Join Date: Mar 2013 Location: Quebec iTrader: (0)	Brake wear measurement Just purchased my E90 about 3 weeks ago... Dealer performed a pre delivery inspection and found the rear brake pads to be at 9mm - which they say is well within limits for the car to be certified. I just put my 19s on last week and my technician (non BMW) noticed that I had aprox 1/16" of rear brake pads left before getting to the warning probe. I made 1700km since taking possession of the car. Could the rear pads have faded that quickly during very normal driving? Or does it mean that the tech who did the "certified" inspection screw up on his measurement? __________________ ___________________________________ 08' M3 Sedan / 08' M3 Coupe / 06 M5 / 03' 996 Targa / 01' 740i / 02' M3 coupe / 01' M5 / 01' 740i Sport / 00' 740i / 94' 325is / 94' 535i / 93' 735i / 91' 850i / 91 E30 325i / 87' 325is / 85' 325e coupe / 04' E55 AMG / 72' Citroen SM
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04-24-2013, 02:01 PM	#2
jphughan Brigadier General 594 Rep 4,488 Posts Drives: '16 Cayman GT4 Join Date: Mar 2011 Location: Austin, TX iTrader: (0)	Maybe they're not looking at the same pads? It's pretty common for quicker inspections to only check the outer brake pads rather than the inner ones, which don't always wear quite evenly. I'm also not sure what the thickness threshold is for the wear sensor to be tripped. But to answer your question, no 1700 km of normal driving shouldn't have produced any noticeable wear even on the fronts, certainly not the rears. Rear pads should last probably 35-45K road miles, if not more. __________________ '16 Cayman GT4 (delivery pics, comparison to E92 M3 write-up) Gone but not forgotten: '11.75 M3 E92 Le Mans \| Black Nov w/ Alum \| 6MT (owned 5/2011 - 11/2015)
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04-24-2013, 02:02 PM	#3
ms372 White Shark 88 Rep 919 Posts Drives: AW E92 m3 6MT Join Date: Mar 2012 Location: Montreal iTrader: (0)	go into your iDrive under info, you should find how much is left in your breaks before the warning comes on. __________________ ESS \| Challenge x-pipe \| Akrapovic \| Stoptech BBK (380/355) \|Ohlins R&T \| Dinan \| Vorsteiner \| Downforce USA \| Varis Diffuser \| Gintani \| UUC \| BMW Performance \| Macht Schnell \| Forgestar F14's SDC 19x9.5F 19x11R \| 255.35 295.30
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04-24-2013, 02:08 PM	#5
FVM3 Major General 273 Rep 5,751 Posts Drives: e92 m3, f30 328i Join Date: Sep 2010 Location: Los Angeles iTrader: (2)	probably different pads. Replace them asap
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04-24-2013, 02:32 PM	#7
1MOREMOD - 11817 Rep 23,187 Posts Drives: Race car-> Join Date: Mar 2009 Location: check your mirrors iTrader: (5)	No way would you see that much use in that short of time. 9mm is almost full thickness. Think they start at around 10 and you can run to about 2-3mm before you break the sensor wire.
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04-24-2013, 03:08 PM	#8
lockeed Second Lieutenant 20 Rep 266 Posts Drives: E90 & E46 M3 E39 M5 E36 325is Join Date: Mar 2013 Location: Quebec iTrader: (0)	Weird indeed... I'll inspect the pads myself and see... In the mean time, I've been denied a set of pads from the dealer... (I'm 700km away from them). __________________ ___________________________________ 08' M3 Sedan / 08' M3 Coupe / 06 M5 / 03' 996 Targa / 01' 740i / 02' M3 coupe / 01' M5 / 01' 740i Sport / 00' 740i / 94' 325is / 94' 535i / 93' 735i / 91' 850i / 91 E30 325i / 87' 325is / 85' 325e coupe / 04' E55 AMG / 72' Citroen SM
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04-24-2013, 03:18 PM	#9
1MOREMOD - 11817 Rep 23,187 Posts Drives: Race car-> Join Date: Mar 2009 Location: check your mirrors iTrader: (5)	That's lame. At least they are cheap. Last time I checked turner has oem rears for 75.
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04-24-2013, 03:33 PM	#10
lockeed Second Lieutenant 20 Rep 266 Posts Drives: E90 & E46 M3 E39 M5 E36 325is Join Date: Mar 2013 Location: Quebec iTrader: (0)	I'll put a listing in the classified section for some rear brake pads! __________________ ___________________________________ 08' M3 Sedan / 08' M3 Coupe / 06 M5 / 03' 996 Targa / 01' 740i / 02' M3 coupe / 01' M5 / 01' 740i Sport / 00' 740i / 94' 325is / 94' 535i / 93' 735i / 91' 850i / 91 E30 325i / 87' 325is / 85' 325e coupe / 04' E55 AMG / 72' Citroen SM
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04-24-2013, 04:16 PM	#12
lockeed Second Lieutenant 20 Rep 266 Posts Drives: E90 & E46 M3 E39 M5 E36 325is Join Date: Mar 2013 Location: Quebec iTrader: (0)	I'm in Quebec - there's gona be a ton of import fees and taxes just on shipping... Not really an option unless the price is ridiculous... __________________ ___________________________________ 08' M3 Sedan / 08' M3 Coupe / 06 M5 / 03' 996 Targa / 01' 740i / 02' M3 coupe / 01' M5 / 01' 740i Sport / 00' 740i / 94' 325is / 94' 535i / 93' 735i / 91' 850i / 91 E30 325i / 87' 325is / 85' 325e coupe / 04' E55 AMG / 72' Citroen SM
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04-24-2013, 09:49 PM	#13
lockeed Second Lieutenant 20 Rep 266 Posts Drives: E90 & E46 M3 E39 M5 E36 325is Join Date: Mar 2013 Location: Quebec iTrader: (0)	I'm wondering, do I need to replace the brake pad sensor while putting new pads at the rear? __________________ ___________________________________ 08' M3 Sedan / 08' M3 Coupe / 06 M5 / 03' 996 Targa / 01' 740i / 02' M3 coupe / 01' M5 / 01' 740i Sport / 00' 740i / 94' 325is / 94' 535i / 93' 735i / 91' 850i / 91 E30 325i / 87' 325is / 85' 325e coupe / 04' E55 AMG / 72' Citroen SM
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04-25-2013, 08:08 AM	#15
lockeed Second Lieutenant 20 Rep 266 Posts Drives: E90 & E46 M3 E39 M5 E36 325is Join Date: Mar 2013 Location: Quebec iTrader: (0)	Thx for the answer __________________ ___________________________________ 08' M3 Sedan / 08' M3 Coupe / 06 M5 / 03' 996 Targa / 01' 740i / 02' M3 coupe / 01' M5 / 01' 740i Sport / 00' 740i / 94' 325is / 94' 535i / 93' 735i / 91' 850i / 91 E30 325i / 87' 325is / 85' 325e coupe / 04' E55 AMG / 72' Citroen SM
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