Would you accept warped discs at 20k miles.
Discussion
Recently my M140 developed some brake judder. Assumed warped discs although it may well have been wheel or steering related so let BMW diagnose.
They have called to say I need new front discs and pads as drivers side front is warped.
Car has only done 20k miles and it seems a bit crap that a set of discs can not out last a set of pads.
The pads still have 3-4mm.
My points were:
If I had changed the pad to some track specials and then killed discs, fair enough.
If i had killed off a whole set of pads in 6k miles and then complained, id accept a degree of "heavy use/ abuse" to blame.
They have offered slightly reduced labour and parts rates as I showed them that forum sponsor dealerships can provide parts cheaper, but has anyone ever got anywhere with a problem like this.
Do I have a leg to stand on or, as the dealership told me, is it simply old school to expect two sets of pads to a set of discs. if it makes any difference only one disc is warped.
They have called to say I need new front discs and pads as drivers side front is warped.
Car has only done 20k miles and it seems a bit crap that a set of discs can not out last a set of pads.
The pads still have 3-4mm.
My points were:
If I had changed the pad to some track specials and then killed discs, fair enough.
If i had killed off a whole set of pads in 6k miles and then complained, id accept a degree of "heavy use/ abuse" to blame.
They have offered slightly reduced labour and parts rates as I showed them that forum sponsor dealerships can provide parts cheaper, but has anyone ever got anywhere with a problem like this.
Do I have a leg to stand on or, as the dealership told me, is it simply old school to expect two sets of pads to a set of discs. if it makes any difference only one disc is warped.
MrBarry123 said:
Isn't the general view that it's unlikely to be warped discs and much more likely to be pad material deposited on the disc? As such, before I'd replace anything, I'd take it for a spirited drive with some heavy braking and see if that helps.
Yea this has been well and truly tried lol. It did not improve unfortunately.kiethton said:
Are you sure you’re braking hard enough?
Had the same with my fiancé’s M135i after I did a 15 Min session on track. Is almost definitely pad deposits.
I did a few very heavy (100-20mph) brake to the carpet emergency stops and it cleaned them 100%
Yeah definitely, i done several 120+ - 30/40. Have tried it on more than 1 occasion as well last time they were glowing and crackling. I will just have to go ahead with replacements then. Had the same with my fiancé’s M135i after I did a 15 Min session on track. Is almost definitely pad deposits.
I did a few very heavy (100-20mph) brake to the carpet emergency stops and it cleaned them 100%
Pad transfer is normal. In fact, it is how modern brake compounds work. Pad and disc heats up, material is transferred to the moving disc, and it is this material on the disc which provides the friction against the pad.
I'm guessing that it is an auto box?
The problem with spirited driving and an auto is that when you come to a stop, you have to keep your foot on the brake to prevent the car creeping. When doing this with a very hot disc, the pad is pressed against the same place on the hot disc and you get excessive pad transfer in that place on the disc.
Then, in normal use the area of excessive transfer has more friction than the rest of the disc. More friction, more heat and the pad transfer continues. Sometimes, excessively hard braking (abuse) can create a layer of equal thickness across the disc and the problem goes away. Pretty rare in my experience.
Brake vibrations of this nature are almost entirely the result of the driver holding the foot on the brake whilst stationary.
I'm guessing that it is an auto box?
The problem with spirited driving and an auto is that when you come to a stop, you have to keep your foot on the brake to prevent the car creeping. When doing this with a very hot disc, the pad is pressed against the same place on the hot disc and you get excessive pad transfer in that place on the disc.
Then, in normal use the area of excessive transfer has more friction than the rest of the disc. More friction, more heat and the pad transfer continues. Sometimes, excessively hard braking (abuse) can create a layer of equal thickness across the disc and the problem goes away. Pretty rare in my experience.
Brake vibrations of this nature are almost entirely the result of the driver holding the foot on the brake whilst stationary.
kiethton said:
Are you sure you’re braking hard enough?
Had the same with my fiancé’s M135i after I did a 15 Min session on track. Is almost definitely pad deposits.
I did a few very heavy (100-20mph) brake to the carpet emergency stops and it cleaned them 100%
Yeah definitely, i done several 120+ - 30/40. Have tried it on more than 1 occasion as well last time they were glowing and crackling. I will just have to go ahead with replacements then. Had the same with my fiancé’s M135i after I did a 15 Min session on track. Is almost definitely pad deposits.
I did a few very heavy (100-20mph) brake to the carpet emergency stops and it cleaned them 100%
+1 on brake pad deposit or maybe even some run out. But that would likely have shown up sooner. Suspect highly unlikely the discs are warped. Although if you say you have them glowing red and cracking, then that probably isn't a good thing either. In which case, if that is your use, 20,000 miles is probably 18,000 miles more than you deserve 
300bhp/ton said:
+1 on brake pad deposit or maybe even some run out. But that would likely have shown up sooner. Suspect highly unlikely the discs are warped. Although if you say you have them glowing red and cracking, then that probably isn't a good thing either. In which case, if that is your use, 20,000 miles is probably 18,000 miles more than you deserve
Haha no the glowing was mild, but after repeated high speed braking to try and get rid of any deposits. They are not cracked they were crackle-ing as in noisy. I cant be that abusive the pads still have 3-4mm and i have done 20k. I am not very heavy on brakes, generally. stevesingo said:
.........I'm guessing that it is an auto box?
The problem with spirited driving and an auto is that when you come to a stop, you have to keep your foot on the brake to prevent the car creeping..........
No you don't - You can put the gearbox into park, or neutral with the hand brake on.The problem with spirited driving and an auto is that when you come to a stop, you have to keep your foot on the brake to prevent the car creeping..........
In fact, in certain situations, such as when it's raining, or at night time, it's bloody discourteous to drivers behind to sit for prolonged periods blinding them with your brake lights!
Not that it helps but just had BMW replace front pads and discs on 2016 M3 with 32k miles for the same reason all done under warranty. Car has not been driven hard (much) and had approx 50% life left in front pads so assuming much more with the discs. Shouldn't happen at such low mileage IMO. I had a 2006 325Ci which had done 150k and was still on original discs and second set of pads when it died. Mind you they don't build them as well these days...
4rephill said:
stevesingo said:
.........I'm guessing that it is an auto box?
The problem with spirited driving and an auto is that when you come to a stop, you have to keep your foot on the brake to prevent the car creeping..........
No you don't - You can put the gearbox into park, or neutral with the hand brake on.The problem with spirited driving and an auto is that when you come to a stop, you have to keep your foot on the brake to prevent the car creeping..........
In fact, in certain situations, such as when it's raining, or at night time, it's bloody discourteous to drivers behind to sit for prolonged periods blinding them with your brake lights!
The majority do though.
Liamst said:
Yeah definitely, i done several 120+ - 30/40. Have tried it on more than 1 occasion as well last time they were glowing and crackling. I will just have to go ahead with replacements then.
How do you know they were glowing? Did you get out and look when the car was stopped? Red hot pad against red hot disc?Can't see how pad transfer happened?
stevesingo said:
Pad transfer is normal. In fact, it is how modern brake compounds work. Pad and disc heats up, material is transferred to the moving disc, and it is this material on the disc which provides the friction against the pad.
.
Any evidence to support that? If what you say were true discs wouldn’t wear as they do, quite consistently these days, I wouldn’t think. .
The more I think about it the more I doubt it, in fact. There are so many reasons why it seems improbable.
I stand to be corrected.
I'd want BMW to be paying for your discs OP - but good luck with that!
My mother bought a new 1.1 Fiesta in 1978 and it went in for a service. The dealer called to say it needed new discs (not pads) at about 15K miles, but later that day Ford called her for some feedback on her ownership experience and I answered the call! It got new discs courtesy of Ford.
My BMW 123d got to 81K on it's original discs and pads, and then I sold it (before the N47 engine exploded)!
My mother bought a new 1.1 Fiesta in 1978 and it went in for a service. The dealer called to say it needed new discs (not pads) at about 15K miles, but later that day Ford called her for some feedback on her ownership experience and I answered the call! It got new discs courtesy of Ford.
My BMW 123d got to 81K on it's original discs and pads, and then I sold it (before the N47 engine exploded)!
REALIST123 said:
stevesingo said:
Pad transfer is normal. In fact, it is how modern brake compounds work. Pad and disc heats up, material is transferred to the moving disc, and it is this material on the disc which provides the friction against the pad.
.
Any evidence to support that? If what you say were true discs wouldn’t wear as they do, quite consistently these days, I wouldn’t think. .
The more I think about it the more I doubt it, in fact. There are so many reasons why it seems improbable.
I stand to be corrected.
http://www.stoptech.com/technical-support/technica...
STOPTECH said:
With adherent friction, some of the pad material diffuses across the interface between the pad and the disc and forms a very thin, uniform layer of pad material on the surface of the disc. As the friction surfaces of both disc and pad then comprise basically the same material, material can now cross the interface in both directions and the bonds break and reform. In fact, with adherent friction between pad and disc, the bonds between pad material and the deposits on the disc are transient in nature - they are continually being broken and some of them are continually reforming.
Edited by stevesingo on Wednesday 3rd October 08:43
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