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M2 Technical Topics > Mechanical Maintenance: Break-in | Oil & Fluids | Servicing | TSB | Recalls > Original rotors bad, but original pads at 50%??

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      08-14-2020, 11:29 PM   #1
flyboy385
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Original rotors bad, but original pads at 50%??

I have a 2018 M2 N55 with 35,000 miles. My brakes started squealing quite loud when they were hot at around 30,000 miles. I understand M brakes are noisy, but it has gotten worse recently and started squeaking even when not hot, to the point where I have had multiple other motorists AND pedestrians comment on it and how bad it is. When I took my car into an independent mechanic for a separate issue, they measured my front rotors at 28.1mm (28.4 is the minimum spec stamped on the wheel hub). We didn't measure the pads, since they were visibly totally fine.

When brought into the dealer (still in warranty period) not only could they not verify the squeaking, but they measured my ORIGINAL brake pads at 6mm and said they would not cover replacement brakes even though the rotors are somehow shot before the original pads are below 50%. The service advisor was as confused as I was, having never heard of such a thing in the 20 years he had been there. The warranty department would not cover it because I didn't buy the "brake warranty" when I bought the car. I have never tracked the car and don't thrash it on the street so I'm not sure how else this could've happened other than maybe a manufacturing defect, which somehow affected all 4 brakes? That doesn't really make sense either...

Does anyone have any kind of insight on how this may have come to be?

My 135i I owned before the M2 lasted 25,000 miles on the first set of pads and 45,000 miles on the original rotors... back then I was young(er) and dumb(er) and spanked the hell out of it.
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      08-15-2020, 02:15 AM   #2
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Quote:
Originally Posted by flyboy385 View Post
I have a 2018 M2 N55 with 35,000 miles. My brakes started squealing quite loud when they were hot at around 30,000 miles. I understand M brakes are noisy, but it has gotten worse recently and started squeaking even when not hot, to the point where I have had multiple other motorists AND pedestrians comment on it and how bad it is. When I took my car into an independent mechanic for a separate issue, they measured my front rotors at 28.1mm (28.4 is the minimum spec stamped on the wheel hub). We didn't measure the pads, since they were visibly totally fine.

When brought into the dealer (still in warranty period) not only could they not verify the squeaking, but they measured my ORIGINAL brake pads at 6mm and said they would not cover replacement brakes even though the rotors are somehow shot before the original pads are below 50%. The service advisor was as confused as I was, having never heard of such a thing in the 20 years he had been there. The warranty department would not cover it because I didn't buy the "brake warranty" when I bought the car. I have never tracked the car and don't thrash it on the street so I'm not sure how else this could've happened other than maybe a manufacturing defect, which somehow affected all 4 brakes? That doesn't really make sense either...

Does anyone have any kind of insight on how this may have come to be?

My 135i I owned before the M2 lasted 25,000 miles on the first set of pads and 45,000 miles on the original rotors... back then I was young(er) and dumb(er) and spanked the hell out of it.
Warranty covers manufacturing defects not wear and tear. If you can prove its a manufacturing defect then by all means go at BMW. I think its too late for that as any evidence is destroyed (im thinking the disk was not properly hardened). Only the first couple mm of the disk are hardened thats why they are toast after the min. thickness.

If your disk is under the minimum wear you should replace it ASAP as you are now wearing the "soft" metal. This will reduce braking performance and cause all the issues you are mentioning.

Also the brake pads start with about 17.9mm of material and are done when they have 3.7mm of material left. If yours are at 6mm then they are almost toast and not at 50%.

Source: https://www.newtis.info/tisv2/a/en/f...ation/GsDShuvI

Source:https://www.bremboparts.com/europe/n...m2/000117272-1

TBH it sounds like your still kinda young and dumb , you have to remember that this is a fast heavy car, and that will chew up brakes.

I will say this feels like very fast wear (im at the start of my 3rd set of track pads with no lip on my discs), but maybe you live in a very hilly area where you use the brakes a lot? or do a lot of hard stops with cold brakes? and did you buy the car new? Previous owner may have ducked it up.

Another interesting tidbit from BMWs service manuals

Retaining pins and expanding spring: for vehicles older than 48 months it is recommended to replace the retaining spring!

The spring loosing tension could lead to more noise.

Source: https://www.newtis.info/tisv2/a/en/f...kes/1VnXy4bj7K

Good luck, but it seems your in for new discs and pads. I recommend looking at upgraded discs as they might last longer.
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      08-15-2020, 07:29 PM   #3
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Yeah, sorry if I sound ignorant, I just had different expectations coming from a non-M that I was more abusive with regarding the brakes. On top of that, having the service advisor telling me he had never seen such a thing along with a similar sentiment from a trusted mechanic led me to believe the worst.

I do live/work in a hilly area, but the hilly parts of town I drive in are slower (no more than 30mph), and again I had different expectations coming from my 135i which I drove in the same areas. I do not do hard stops with cold brakes and I bought the car new.

I really appreciate the detailed info regarding pad specs and the retaining pins/springs. I will be getting the brakes replaced one way or another, so I'll take a look at those as well.

Could be a good excuse for a brake upgrade...
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      08-15-2020, 08:01 PM   #4
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One of the ways BMW gets such good braking out of this car (initially) is with aggressive pads that literally eat rotors. It's why you don't have to use much effort to get the car to stop very short. If you're not tracking the car your very first mod should be the Akebono pads IMO.
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      08-16-2020, 03:01 AM   #5
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Quote:
Originally Posted by flyboy385 View Post
Yeah, sorry if I sound ignorant, I just had different expectations coming from a non-M that I was more abusive with regarding the brakes. On top of that, having the service advisor telling me he had never seen such a thing along with a similar sentiment from a trusted mechanic led me to believe the worst.

I do live/work in a hilly area, but the hilly parts of town I drive in are slower (no more than 30mph), and again I had different expectations coming from my 135i which I drove in the same areas. I do not do hard stops with cold brakes and I bought the car new.

I really appreciate the detailed info regarding pad specs and the retaining pins/springs. I will be getting the brakes replaced one way or another, so I'll take a look at those as well.

Could be a good excuse for a brake upgrade...
My comment about young and dumb is just riffing off your 1st post. I meant it toungue in cheek without meaning to offend.

Asking questions and trying to develop your knowledge is the smartest and most mature thing I know.

Its honestly a bit puzzeling how you wore the disc/pads so fast. Maybe its the stock pads because as I said I have used 2 sets of trackpads in about 12k miles and my discs are good on thickness (not on hairline cracks and heat abuse though).

Are you bumping into the TC a lot? thats also not good for pad/disc longevity.
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      08-17-2020, 04:40 AM   #6
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Why aren't you thrashing it on the street? What's the point.
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      09-18-2020, 09:52 PM   #7
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Quote:
Originally Posted by flyboy385 View Post
I have a 2018 M2 N55 with 35,000 miles. My brakes started squealing quite loud when they were hot at around 30,000 miles. I understand M brakes are noisy, but it has gotten worse recently and started squeaking even when not hot, to the point where I have had multiple other motorists AND pedestrians comment on it and how bad it is. When I took my car into an independent mechanic for a separate issue, they measured my front rotors at 28.1mm (28.4 is the minimum spec stamped on the wheel hub). We didn't measure the pads, since they were visibly totally fine.

When brought into the dealer (still in warranty period) not only could they not verify the squeaking, but they measured my ORIGINAL brake pads at 6mm and said they would not cover replacement brakes even though the rotors are somehow shot before the original pads are below 50%. The service advisor was as confused as I was, having never heard of such a thing in the 20 years he had been there. The warranty department would not cover it because I didn't buy the "brake warranty" when I bought the car. I have never tracked the car and don't thrash it on the street so I'm not sure how else this could've happened other than maybe a manufacturing defect, which somehow affected all 4 brakes? That doesn't really make sense either...

Does anyone have any kind of insight on how this may have come to be?

My 135i I owned before the M2 lasted 25,000 miles on the first set of pads and 45,000 miles on the original rotors... back then I was young(er) and dumb(er) and spanked the hell out of it.
The 28.4mm is minimum thickness for rotor replacement when doing a new set of pads. If the rotors were at 28.5mm when needing new pads, technically the rotors are ok to be reused. Sounds like the independent shop is trying to upsell brakes are cars that don't need them.
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