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      01-19-2020, 10:40 AM   #1
kv1980
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Brake wear sensor

Hi all,

I noticed today (correct me when I'm wrong) that Idrive 7 doesn't show the state of the brakes. In my 1-series you can see when the brakes need replacement (shows remaining kms)...
In my Z4 you can see when the brake-oil needs replacement and other service info but that's all...
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      01-23-2020, 01:26 AM   #2
freshxdough
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Originally Posted by kv1980 View Post
Hi all,

I noticed today (correct me when I'm wrong) that Idrive 7 doesn't show the state of the brakes. In my 1-series you can see when the brakes need replacement (shows remaining kms)...
In my Z4 you can see when the brake-oil needs replacement and other service info but that's all...
The newer vehicles (last 4 years or so) got rid of the estimated due mileage for front and rear brakes. The calculation was always wrong anyway. They still use brake pad sensors, you just won't get a check control message until the brake pad sensor is actually cut which is far more accurate of the brakes actually being due.
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      01-29-2020, 11:24 AM   #3
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Quote:
Originally Posted by freshxdough View Post
The newer vehicles (last 4 years or so) got rid of the estimated due mileage for front and rear brakes. The calculation was always wrong anyway. They still use brake pad sensors, you just won't get a check control message until the brake pad sensor is actually cut which is far more accurate of the brakes actually being due.
My 2016 M4 still has an estimated range for brake pad replacement, so does my wife's 2018 M3.

Here's what happens though when you let the brake pads wear down enough to grind down the sensor and trip the the sensor circuit:

I track my M4 and I use Pagid brakes pads for the track, which I swap back and forth with my stock pads for the street. I've gone through two sets of front pads, but the rear track pads have lasted for 3.5 years of occasional track usage. They were getting pretty thin though and I was planning to replace the entire set after the next track weekend.

Long story short, on day 2 of a 3-day track weekend, I wore through the rear brake sensor and it tripped the brake warning, which was prominently displayed on the dash and in iDrive for the rest of the weekend and all the way home. I had to OK the message every time I started the car. I got home, swapped the track pads back to the street pads, replaced the rear brake sensor, reset the estimated mileage indicator and everything was fine.

A couple of days later I get a text from my dealer indicating that my brakes needed replacement and to schedule the service. I replied, explaining the situation, and basically said, no worries.

Then I got an e-mail and then a phone call. According to the woman who called, when the brake sensor tripped, the car sent a service request to the dealer for brake service. Since it was brakes, they were adamant that I had to come in for service. I explained to her that I was at the track, the rear track pads wore down, tripped the sensor, but were fine until I got home. I told them that I swapped in the stock pads, replaced and reset the sensor, and everything was fine. She seemed satisfied with that explanation, said that she would make a note that the brakes had been replaced and I haven't heard from them since.

If the brake sensor gets tripped, the service for the brakes will now include the cost of a new brake sensor, about $25 for the rear sensor on the M4, about $40 for the front, plus probably about 0.5 - 1.0 hrs of billable shop time to replace the sensor. With the estimated range, people will at least know when their brakes need to be checked, rather than be faced with an immediate brake replacement.

P.S. I just noticed that you have BMW Master Technician listed under your username, so you already know all of this!
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      01-29-2020, 01:05 PM   #4
freshxdough
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Quote:
Originally Posted by SD ///M4 View Post
Quote:
Originally Posted by freshxdough View Post
The newer vehicles (last 4 years or so) got rid of the estimated due mileage for front and rear brakes. The calculation was always wrong anyway. They still use brake pad sensors, you just won't get a check control message until the brake pad sensor is actually cut which is far more accurate of the brakes actually being due.
My 2016 M4 still has an estimated range for brake pad replacement, so does my wife's 2018 M3.
The F80 is probably the last ones to have it considering it's ending production very soon and it's ideive 5 i believe. I meant more of idrive 6 and 7 cars, mostly G and F cars. BMW probably realized giving an estimated distance was worse because once the calculation is incorrect the brakes will show due in 3,100 miles and won't move off that range until the sensor is cut. So you could be at 10mm pad and show due in 3,100 for tens of thousands of miles. Then you have customers coming into service asking to get their brakes done even though the calculation is incorrect and now customers think we're lying about the brakes being way above spec and it's just a big debacle.

It's better to just do the brakes when the brakes are due from the pad sensor being cut. When the pad sensor is cut it you could still go a couple thousand so it's not an emergency to get them replaced instantly.
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      01-29-2020, 01:18 PM   #5
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Originally Posted by freshxdough View Post
The F80 is probably the last ones to have it considering it's ending production very soon and it's ideive 5 i believe. I meant more of idrive 6 and 7 cars, mostly G and F cars.
I have iDrive 4 in my 2016 M4 and my wife has iDrive 6 in her 2018 M3.

M3 production was done last October and M4 production is done in June this year.
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