Has the stock pad issue been resolved; has BMW switched the stock pad compound?

[Absurdium]

Hello all. I recently purchased my F82 and have been very happy with it. Coming from an E92, the upgraded brakes were one of the highlights I was looking forward to. However recently, I noticed a slight vibration at high speed braking when the brakes are cold; as temperature warms up, it seems like the issue goes away, or is at least less noticeable. I did take a look at the rotors today and to my surprise, there are several pad outlines on the rear rotors; the front are fine.

I understand the characteristics of brake pads and rotors interaction and that 95% of the time, brake vibration are due to pad deposit. I also take care to cool down the brakes after any spirited driving or heavy braking to avoid leaving any deposits. I did initially bed in the pads when first getting the car but perhaps I was not aggressive enough.

After a quick search, I understand that many people have issues with this problem as there has been numerous threads on brake vibration, all seemingly due to pad deposits. The consensus appears to be that the pads are the issue as the stock rotors are quite robust. There seems to be some speculation that BMW has secretly replaced the pad material to prevent this issue from happening. However as you can see from the pictures, mine still left imprints, which if I'm not careful may turn into heavy deposits. I'll be bedding in my pads again later tonight to see that gets rid of them. Interestingly, I ran my finger through the imprints and they felt perfectly smooth.

Just wanted to see what has everyone else's experience been recently. Seems like the problem is not as common with the later build cars.

If this is still an issue, I may switch to stoptech 309s as they had good reviews as a aggressive street pad. So as a side question, anyone have any experience with stoptech 309s (now called stoptech sport) on the F8x platform?

[IrvineTim]

Were your rims in a fire dude or what? Man, what happened to your rims!!

[Absurdium]

Originally Posted by IrvineTim

Were your rims in a fire dude or what? Man, what happened to your rims!!

Haha, this is what winter driving in Ontario will get you. Luckily I got a set of cheap 220M from my E92 that I don't care too much about.

[Powerslide]

I'm skeptical about BMW changing the pad compound. I bought my 2018 ZCP in November of 2017. By late January 2018, with about 2800 miles on the car, I had brake judder. The rotors were found to be "out of spec" (which is what happens when uneven pad imprint or deposit gets on there), and the pads/rotors were changed under warranty.

For the first couple of weeks after that, the brakes were as smooth as glass decelerating from any speed, whether light, medium or heavy braking force. However, after about 2 weeks, I started to notice an ever so-slight amount of vibration when braking (so slight that I wasn't sure if I was actually feeling it, or if it was my imagination/paranoia). However, I am now about a month and 1500 miles post-pad/rotor replacement, and there is definitely some vibration/judder on deceleration (although not as bad as before the pad/rotor replacement). On a couple of occasions this past week, I also noticed some pad imprint on the rotors (I always try to cool down the brakes for a long time before coming to a complete stop - so I've also been incredibly careful trying to avoid pad imprint through complete stops on hot brakes).

So - if BMW did change the compound, it seems to have only made a slight improvement. As I've stated in many other posts since I switched from an E93 M3 (which never had brake vibration/judder issues), to an F80 in 2014, every single winter since then I've had brake judder.

One last point - in past winters, I didn't bed the brakes, and I'm usually less hard on the brakes in the winter vs. spring, summer and fall. After getting my rotors/pads replaced in late January, I decided two things: 1) I was going to bed my brakes in the manner described on the StopTech site (which I did a week after they were replaced); and 2) be "harder" on the brakes compared to prior winters. After bedding my brakes at week 1, and then re-bedding them at week 2, the brakes were still "smooth as glass" when stopping. However, these two beddings did not stop the very gradual, and at first almost imperceptible return of the vibration/judder.

I still find it incredibly interesting that I have this problem every single winter, but not once has it happened to me in the Spring, Summer or Fall.

In February 2017, I swapped my stock pads and put in my Pagid RS29's. The brake judder seemed to only mildly improve over the next month and 2,000-2,500 miles. But all of a sudden in April of 2017 (with my Pagid RS29's still in) the judder completely disappeared within a few days, and my brakes were once again "smooth as glass," and remained that way all the way to November.

Did the RS29's "scrape" away the uneven deposits? Maybe. But here's the thing - I noticed almost zero improvement for the first several weeks in February and March when the RS29's were in (daily driving the whole time, averaging 1,500 miles per month). Imagine having a 5% improvement after 2 weeks, 10% improvement 2 weeks later, and then going from 30% better at week 5 to 100% better at week 6!! It seems that the sudden improvement at the end correlated much more to the sudden warm-up in weather (and when no salt getting thrown down on the roads anymore) than with the amount of time/miles with the RS29 pads in.

So what am I going to do? Just for experimental purposes, I might try to just live with the minor judder until early April (which is when the problem suddenly disappeared last year) and see if it disappears on its own again (but this time, with stock pads instead of RS29's).

Should be interesting. If that doesn't work, I'll get them replaced under warranty again, and stop using the stock pads for good for a different aggressive street pad instead...

Let's keep this tread going - the more people chime in, the sooner the exact, root cause and best solution will be discovered.

[Absurdium]

Originally Posted by Powerslide

I'm skeptical about BMW changing the pad compound. I bought my 2018 ZCP in November of 2017. By late January 2018, with about 2800 miles on the car, I had brake judder. The rotors were found to be "out of spec" (which is what happens when uneven pad imprint or deposit gets on there), and the pads/rotors were changed under warranty.

For the first couple of weeks after that, the brakes were as smooth as glass decelerating from any speed, whether light, medium or heavy braking force. However, after about 2 weeks, I started to notice an ever so-slight amount of vibration when braking (so slight that I wasn't sure if I was actually feeling it, or if it was my imagination/paranoia). However, I am now about a month and 1500 miles post-pad/rotor replacement, and there is definitely some vibration/judder on deceleration (although not as bad as before the pad/rotor replacement). On a couple of occasions this past week, I also noticed some pad imprint on the rotors (I always try to cool down the brakes for a long time before coming to a complete stop - so I've also been incredibly careful trying to avoid pad imprint through complete stops on hot brakes).

So - if BMW did change the compound, it seems to have only made a slight improvement. As I've stated in many other posts since I switched from an E93 M3 (which never had brake vibration/judder issues), to an F80 in 2014, every single winter since then I've had brake judder.

One last point - in past winters, I didn't bed the brakes, and I'm usually less hard on the brakes in the winter vs. spring, summer and fall. After getting my rotors/pads replaced in late January, I decided two things: 1) I was going to bed my brakes in the manner described on the StopTech site (which I did a week after they were replaced); and 2) be "harder" on the brakes compared to prior winters. After bedding my brakes at week 1, and then re-bedding them at week 2, the brakes were still "smooth as glass" when stopping. However, these two beddings did not stop the very gradual, and at first almost imperceptible return of the vibration/judder.

I still find it incredibly interesting that I have this problem every single winter, but not once has it happened to me in the Spring, Summer or Fall.

In February 2017, I swapped my stock pads and put in my Pagid RS29's. The brake judder seemed to only mildly improve over the next month and 2,000-2,500 miles. But all of a sudden in April of 2017 (with my Pagid RS29's still in) the judder completely disappeared within a few days, and my brakes were once again "smooth as glass," and remained that way all the way to November.

Did the RS29's "scrape" away the uneven deposits? Maybe. But here's the thing - I noticed almost zero improvement for the first several weeks in February and March when the RS29's were in (daily driving the whole time, averaging 1,500 miles per month). Imagine having a 5% improvement after 2 weeks, 10% improvement 2 weeks later, and then going from 30% better at week 5 to 100% better at week 6!! It seems that the sudden improvement at the end correlated much more to the sudden warm-up in weather (and when no salt getting thrown down on the roads anymore) than with the amount of time/miles with the RS29 pads in.

So what am I going to do? Just for experimental purposes, I might try to just live with the minor judder until early April (which is when the problem suddenly disappeared last year) and see if it disappears on its own again (but this time, with stock pads instead of RS29's).

Should be interesting. If that doesn't work, I'll get them replaced under warranty again, and stop using the stock pads for good for a different aggressive street pad instead...

Let's keep this tread going - the more people chime in, the sooner the exact, root cause and best solution will be discovered.

Thanks for the detailed write-up! I think I actually stumbled on one of your posts before and I agree, this doesn't seem to make sense. However the quote goes: "once you've ruled out the impossibles, whatever is left, however unlikely, must be the truth." It's obvious we're both knowledgeable enough to be careful with brake cool down and not to clamp the pads on the rotors when hot, yet deposits and imprints still show up.

I will note that at least with my car so far, the vibration seems to go away after they're warm and after I've had a chance to do 1 or two hard stops. Part of me is thinking maybe it's due to the excessive rust build up in winter that creates an uneven layer of material on the rotor; once you scrub these away, the vibration will go away. However if this were true, I'm not sure why there are still imprints on my rear rotors as you can see in the pictures.

Unfortunately I have heard horror stories of dealers refusing to warranty rotors and especially since I'm in Canada, where rotor and pads are not part of the maintenance program. However I've had my car for 1 month so I doubt they'll turn me away if I really do get vibration issues.

Gonna try bedding in my stock pads tonight to see if I can scrub away the imprints that only seem to have a visible mark (felt them with my hands, they were indistinguishable and perfectly smooth with the rotor). I've had brake judder/vibration issues in the past with both a 335is and a E92 M3 (although I take partial responsibility as I did not understand proper brake cool down procedures before) so I've been super careful with not stopping on them when hot. Definitely bummed out that the stock pads seem inadequate, on what otherwise seems like a very robust brake system. Will update post the bed-in procedure

[Powerslide]

Originally Posted by Absurdium

Thanks for the detailed write-up! I think I actually stumbled on one of your posts before and I agree, this doesn't seem to make sense. However the quote goes: "once you've ruled out the impossibles, whatever is left, however unlikely, must be the truth." It's obvious we're both knowledgeable enough to be careful with brake cool down and not to clamp the pads on the rotors when hot, yet deposits and imprints still show up.

I will note that at least with my car so far, the vibration seems to go away after they're warm and after I've had a chance to do 1 or two hard stops. Part of me is thinking maybe it's due to the excessive rust build up in winter that creates an uneven layer of material on the rotor; once you scrub these away, the vibration will go away. However if this were true, I'm not sure why there are still imprints on my rear rotors as you can see in the pictures.

Unfortunately I have heard horror stories of dealers refusing to warranty rotors and especially since I'm in Canada, where rotor and pads are not part of the maintenance program. However I've had my car for 1 month so I doubt they'll turn me away if I really do get vibration issues.

Gonna try bedding in my stock pads tonight to see if I can scrub away the imprints that only seem to have a visible mark (felt them with my hands, they were indistinguishable and perfectly smooth with the rotor). I've had brake judder/vibration issues in the past with both a 335is and a E92 M3 (although I take partial responsibility as I did not understand proper brake cool down procedures before) so I've been super careful with not stopping on them when hot. Definitely bummed out that the stock pads seem inadequate, on what otherwise seems like a very robust brake system. Will update post the bed-in procedure

Yes - agree with everything you said above. The fact that:

1) I'm less "hard" on the brakes in the winter vs. spring, summer or fall;

2) I'm more careful to avoid holding my foot down on the brake when at a complete stop in the winter than I am in the spring, summer or fall; and

3) In Chicago (just like in Ontario), the outside temperature is far colder in the winter than in the rest of the year (especially summer), so if anything, the pads and rotors would seemingly be much more prone to pad deposits being imprinted on the rotors in the spring, summer or fall, yet the problem repeatedly happens under conditions which would seem the LEAST conducive to pad deposits!!??

So why we are both getting pad imprint on the rotors in the winter, and not the spring, summer or fall is about as counter-intuitive as it gets!!! There is obviously a scientific answer that us forum members have not yet figured out -but the undeniable correlation to the problem with winter is very intriguing...

[Absurdium]

Originally Posted by Powerslide

Yes - agree with everything you said above. The fact that:

1) I'm less "hard" on the brakes in the winter vs. spring, summer or fall;

2) I'm more careful to avoid holding my foot down on the brake when at a complete stop in the winter than I am in the spring, summer or fall; and

3) In Chicago (just like in Ontario), the outside temperature is far colder in the winter than in the rest of the year (especially summer), so if anything, the pads and rotors would seemingly be much more prone to pad deposits being imprinted on the rotors in the spring, summer or fall, yet the problem repeatedly happens under conditions which would seem the LEAST conducive to pad deposits!!??

So why we are both getting pad imprint on the rotors in the winter, and not the spring, summer or fall is about as counter-intuitive as it gets!!! There is obviously a scientific answer that us forum members have not yet figured out -but the undeniable correlation to the problem with winter is very intriguing...

I feel you buddy. Really doesn't make much sense to me. I want to say it has to do with the salt and temperature issue but I'm not sure what physical process would create the result we're experiencing.

I did just re-bed in my brakes. I feel slightly nauseous now... However it seems like some of the pad imprint was wiped off, but then some new ones are on there? Maybe I just didn't notice them before. I did drive without stopping at all for 10 mins after the procedure and had to dab on them slightly for a few right turns. I'm seeing a big deposit spot now on my front now though.. not sure if this is from the re-bed in or I just didn't notice it before. The good news however, is that the braking is super smooth. Maybe the mark on the front rotor is just a flat mark, like I saw with the rear rotors.

I think my plan going forward is to just drive on them normally and see if anything else develop. If so, I'll just warranty them and get the stoptech sport pads. If not, I'll switch to the stoptech pads regardless as I want more confidence in my brakes and I don't really want to have to deal with potentially replacing the rotors out of pocket; pads are much cheaper mind you

Edit: Went outside to feel the apparent marks on the rotors after they had some time to cool. Happy to report that the marks were actually completely flat, and doesn't appear to be problematic deposits. Some of the marks left actually wiped off, so I believe they were just brake dust that were on the pad that left the imprint.

New theory: the problem in the winter is that the M4 pads leave pockets of brake dust prints from the pad (not necessarily deposits) that rust and create an uneven surface. This explains why I seem to have brake vibrations only when cold as these rust spots would wear off after a few uses of the brake. The reason why this is going to be more prevalent during the winter is that cold weather causes the pad to be more abrasive, hence more dust. This extra dust leaving the prints that build up over time if you don't clear them off with hard braking in-between use is what causes the vibration.

Either way, I think this exercise cements my decision to switch to a different pad compound for the street. The extra dust from the OEM pads are not very welcome anyways. Will pick up a set of stoptech sports very soon!

[CanAutM3]

Bedding brakes will not get rid of pad imprints or uneven deposit.

The whole point of bedding brakes is to get a smooth layer of pad material on the rotors to favor transfer friction and is mostly necessary with track pads. This is achieved by doing repeated stops to heat up the pads and get them in the transfer friction zone, evenly smear the rotors with pad material and then immediately let them cool down to harden.

To get rid of pad imprints or uneven deposit, you need to use abrasive friction, which is mostly active when the brakes are cool. Normal street driving will do that, but it does take a while.

[Powerslide]

Originally Posted by CanAutM3

Bedding brakes will not get rid of pad imprints or uneven deposit.

The whole point of bedding brakes is to get a smooth layer of pad material on the rotors to favor transfer friction and is mostly necessary with track pads. This is achieved by doing repeated stops to heat up the pads and get them in the transfer friction zone, evenly smear the rotors with pad material and then immediately let them cool down to harden.

To get rid of pad imprints or uneven deposit, you need to use abrasive friction, which is mostly active when the brakes are cool. Normal street driving will do that, but it does take a while.

Thanks for your input. What is strange though is now the uneven deposits got there in the first place. I never drive anywhere near as aggressive in the winter as I do in the rest of the year, so if I don't get this problem when it is warmer (and the pads and rotors are warmer), why is it that this happens in the winter when conditions should be less conducive to pad transfer? Is it related to salt, corrosion or other issues uniquely present in winter, which create the chemical conditions for this to happen?

Since I don't know the root cause for this to happen in the first place, I haven't figured out how to proactively prevent it (aside from being very careful not to press down on the brake pedal when stopped if there is any question about heat being in the rotors/pads - which I have been extremely cognizant of for the past few winters, yet the problem keeps happening).

As far as the remedy for the issue - normal street driving when the pads are in "abrasive" mode - obviously a track pad (RS29) with normal street driving will be more abrasive than the OEM stock pads. However, given a greater amount of time/miles, would it be safe to say that normal street driving with OEM pads should (at least in theory) make the problem eventually go away? (But once again, I was doing normal street braking BEFORE the problem occurred, yet the vibrations surfaced anyway).

Classic what came first - the chicken or the egg dilemna...

[Powerslide]

Originally Posted by Absurdium

I feel you buddy. Really doesn't make much sense to me. I want to say it has to do with the salt and temperature issue but I'm not sure what physical process would create the result we're experiencing.

I did just re-bed in my brakes. I feel slightly nauseous now... However it seems like some of the pad imprint was wiped off, but then some new ones are on there? Maybe I just didn't notice them before. I did drive without stopping at all for 10 mins after the procedure and had to dab on them slightly for a few right turns. I'm seeing a big deposit spot now on my front now though.. not sure if this is from the re-bed in or I just didn't notice it before. The good news however, is that the braking is super smooth. Maybe the mark on the front rotor is just a flat mark, like I saw with the rear rotors.

I think my plan going forward is to just drive on them normally and see if anything else develop. If so, I'll just warranty them and get the stoptech sport pads. If not, I'll switch to the stoptech pads regardless as I want more confidence in my brakes and I don't really want to have to deal with potentially replacing the rotors out of pocket; pads are much cheaper mind you

Edit: Went outside to feel the apparent marks on the rotors after they had some time to cool. Happy to report that the marks were actually completely flat, and doesn't appear to be problematic deposits. Some of the marks left actually wiped off, so I believe they were just brake dust that were on the pad that left the imprint.

New theory: the problem in the winter is that the M4 pads leave pockets of brake dust prints from the pad (not necessarily deposits) that rust and create an uneven surface. This explains why I seem to have brake vibrations only when cold as these rust spots would wear off after a few uses of the brake. The reason why this is going to be more prevalent during the winter is that cold weather causes the pad to be more abrasive, hence more dust. This extra dust leaving the prints that build up over time if you don't clear them off with hard braking in-between use is what causes the vibration.

Either way, I think this exercise cements my decision to switch to a different pad compound for the street. The extra dust from the OEM pads are not very welcome anyways. Will pick up a set of stoptech sports very soon!

Thanks for the update. Just out of curiosity, what exact technique did you use? Whenever I've tried to re-bed the brakes - I'll do as follows:

1) stop hard (just short of ABS intervention) from 60mph down to 5mph;
2) immediately accelerate back up to 65mph;
3) stop hard again (just short of ABS intervetion) from 65mph down to 5mph;
4+) repeat above at least 5-6 more times, then drive around for a good 10-15 minutes straight trying to avoid any brake usage at all, or as minimal as possible, without ever coming to a complete stop.

Do you use this same technique as above or a different technique? When you brake during the rebedding process, do you also apply enough force just short of triggering ABS intervenion? Has ABS ever intervened when doing the rebedding process (due to apply just a little too much brake pedal force)?

Finally - if you could please post whether you have any vibration issues return today or the next few days. If your brakes remain super-smooth for the next few days, then I'm going to go out and do EXACTLY what you did!! This car is such a joy to drive, but every winter somewhat diminishes the fun when the brake pedal and/or steering wheel begin to vibrate every single time you hit the brakes.

[Powerslide]

Originally Posted by CanAutM3

Bedding brakes will not get rid of pad imprints or uneven deposit.

The whole point of bedding brakes is to get a smooth layer of pad material on the rotors to favor transfer friction and is mostly necessary with track pads. This is achieved by doing repeated stops to heat up the pads and get them in the transfer friction zone, evenly smear the rotors with pad material and then immediately let them cool down to harden.

To get rid of pad imprints or uneven deposit, you need to use abrasive friction, which is mostly active when the brakes are cool. Normal street driving will do that, but it does take a while.

Oh - and a few other questions since you also come from a climate very similar to Chicago:

1) Assuming the municipalities/highway authorities in the Montreal area also use salt on the roads in the winter time, and also assuming you DD your car with the stock OEM pads throughout the winter, have you ever experienced brake judder in the brake pedal/steering wheel in the winter time?

2) If any of the assumptions in 1) above are not true, which ones are not, and what is the actual situation you're dealing with?

3) If brake judder has happened to you in the winter (with stock OEM pads), has it ever happened to you in the spring, summer or fall?

4) If you did get brake judder in the winter, do you know what caused it in the first place, and if so, any luck in preventing it from recurring thereafter?

Thanks again for all of your assistance!!!

[Absurdium]

Originally Posted by CanAutM3

Bedding brakes will not get rid of pad imprints or uneven deposit.

The whole point of bedding brakes is to get a smooth layer of pad material on the rotors to favor transfer friction and is mostly necessary with track pads. This is achieved by doing repeated stops to heat up the pads and get them in the transfer friction zone, evenly smear the rotors with pad material and then immediately let them cool down to harden.

To get rid of pad imprints or uneven deposit, you need to use abrasive friction, which is mostly active when the brakes are cool. Normal street driving will do that, but it does take a while.

Yeah you're right about bedding in and brake deposits. However in my case, I realized the pad imprint wasn't actually an imprint of pad material, rather a ring of pad dust that was stamped on to the rotor. Either way I tried to bed in the pads as a preventative measure as I'm not actually experiencing heavy vibration right now. I understand that an even transfer layer not only helps with braking performance, but reduces the likelihood of creating hot spots as the material is more evenly spread out so I felt like this might help me prevent future deposits.

Out of curiosity, what has been your experience with the stock pads? Have you experienced any deposits at all? I'm assuming your car is a DD through winter as well right?

Originally Posted by Powerslide

Thanks for the update. Just out of curiosity, what exact technique did you use? Whenever I've tried to re-bed the brakes - I'll do as follows:

1) stop hard (just short of ABS intervention) from 60mph down to 5mph;
2) immediately accelerate back up to 65mph;
3) stop hard again (just short of ABS intervetion) from 65mph down to 5mph;
4+) repeat above at least 5-6 more times, then drive around for a good 10-15 minutes straight trying to avoid any brake usage at all, or as minimal as possible, without ever coming to a complete stop.

Do you use this same technique as above or a different technique? When you brake during the rebedding process, do you also apply enough force just short of triggering ABS intervenion? Has ABS ever intervened when doing the rebedding process (due to apply just a little too much brake pedal force)?

Finally - if you could please post whether you have any vibration issues return today or the next few days. If your brakes remain super-smooth for the next few days, then I'm going to go out and do EXACTLY what you did!! This car is such a joy to drive, but every winter somewhat diminishes the fun when the brake pedal and/or steering wheel begin to vibrate every single time you hit the brakes.

I use a similar technique as the one you've posted. However there were some differences:

1. Instead of 65-5 mph, I did 75-20mph. However before the bed-in session, I used the brakes a few time from 60-45mph just to get them up to temp. This is to prevent thermo-shocking of the rotor and pad.

2. Instead of 6-7, I did about 10 stops. I actually drove to a road where I knew there was no stop sign or traffic lights for 10km. I felt slight fade in them as I approached the 7-8th stop and kept going until the 10th.

3. Unfortunately, my abs did kick in on the 9th stop. This is why I said I did "about" 10 stops; I did 2-3 extra just to make sure I got an even layer down, despite the abs kicking in. By this time, I was also very close to throwing up on my Silverstone interior, so I felt like it was a good time to wrap it up.

For sure! I'll update you on this in a week's time regardless of how the brakes are. If I do forget, just drop me a mention here and I'll respond as soon as I can. One caveat though, is that I think I started with less vibration than you. My brakes actually only gave a slight hint of it when cold, but the vibration was gone when I drove normally for a few days. It was the visible pad material imprint that inspired me to create this thread.

Either way, I think I will be switch street pads regardless as it seems like the OEM pads are not a good match for this brake system. Changing into a semi-metallic compound like the stoptechs that I'm considering, should add some more abrasive properties that would scrape any deposits with more efficiency, thus making it less likely that deposits will occur. Also in consideration to my theory, I think the abundance of brake dust from the OEM pads combined with the winters that we have, contributes to the probability of deposit build up. This is just my theory of course, but less brake dust will also be a welcomed change.

[CanAutM3]

Originally Posted by Powerslide

Thanks for the update. Just out of curiosity, what exact technique did you use? Whenever I've tried to re-bed the brakes - I'll do as follows:

1) stop hard (just short of ABS intervention) from 60mph down to 5mph;
2) immediately accelerate back up to 65mph;
3) stop hard again (just short of ABS intervetion) from 65mph down to 5mph;
4+) repeat above at least 5-6 more times, then drive around for a good 10-15 minutes straight trying to avoid any brake usage at all, or as minimal as possible, without ever coming to a complete stop.

Do you use this same technique as above or a different technique? When you brake during the rebedding process, do you also apply enough force just short of triggering ABS intervenion? Has ABS ever intervened when doing the rebedding process (due to apply just a little too much brake pedal force)?

Finally - if you could please post whether you have any vibration issues return today or the next few days. If your brakes remain super-smooth for the next few days, then I'm going to go out and do EXACTLY what you did!! This car is such a joy to drive, but every winter somewhat diminishes the fun when the brake pedal and/or steering wheel begin to vibrate every single time you hit the brakes.

One of the better procedures I have come across:

http://www.stoptech.com/technical-su...-system-bed-in

Stoptech likely recommend the "street pad" procedure for liability reasons (by not asking people to drive above 60mph). I would recommend their track pad procedure even for street pads as I don't believe repeated stops from 60mph will be able to put sufficient heat in the F8X braking system.

See Pagid recommended procedure below:"

[CanAutM3]

Originally Posted by Powerslide

Oh - and a few other questions since you also come from a climate very similar to Chicago:

1) Assuming the municipalities/highway authorities in the Montreal area also use salt on the roads in the winter time, and also assuming you DD your car with the stock OEM pads throughout the winter, have you ever experienced brake judder in the brake pedal/steering wheel in the winter time?

2) If any of the assumptions in 1) above are not true, which ones are not, and what is the actual situation you're dealing with?

3) If brake judder has happened to you in the winter (with stock OEM pads), has it ever happened to you in the spring, summer or fall?

4) If you did get brake judder in the winter, do you know what caused it in the first place, and if so, any luck in preventing it from recurring thereafter?

Thanks again for all of your assistance!!!

First, ambient temperatures do not make a significant difference regarding brakes operating temperatures. The temperature reached by the brake system after going through multiple hard stops will be well above 1000degF, the few degrees difference in ambient won't matter much.

Yes, they do apply a crazy amount of salt in Montreal. But I do not believe this is a contributor to brake judder.

I've never suffered from brake judder in my M4, regardless of season. I believe the stock pads on the F8X have relatively strong bias towards performance. I was once stuck having to run my stock front pads at the track, and I was able to pull lap time within half a second from my lap record. The main drawback is wear, I wore down the stock pads in less than a track day. I was also very prudent by not over braking and giving them a good cool down. But their performance was nonetheless quite impressive. This tells me the stock pads have a relatively strong bias of transfer friction built into them and could explain why they are prone to shudder if they are not properly bedded in.

See bedding procedure posted above.

[CanAutM3]

Originally Posted by Powerslide

Thanks for your input. What is strange though is now the uneven deposits got there in the first place. I never drive anywhere near as aggressive in the winter as I do in the rest of the year, so if I don't get this problem when it is warmer (and the pads and rotors are warmer), why is it that this happens in the winter when conditions should be less conducive to pad transfer? Is it related to salt, corrosion or other issues uniquely present in winter, which create the chemical conditions for this to happen?

Since I don't know the root cause for this to happen in the first place, I haven't figured out how to proactively prevent it (aside from being very careful not to press down on the brake pedal when stopped if there is any question about heat being in the rotors/pads - which I have been extremely cognizant of for the past few winters, yet the problem keeps happening).

As far as the remedy for the issue - normal street driving when the pads are in "abrasive" mode - obviously a track pad (RS29) with normal street driving will be more abrasive than the OEM stock pads. However, given a greater amount of time/miles, would it be safe to say that normal street driving with OEM pads should (at least in theory) make the problem eventually go away? (But once again, I was doing normal street braking BEFORE the problem occurred, yet the vibrations surfaced anyway).

Classic what came first - the chicken or the egg dilemna...

I avoid swapping to street pads too early after a track day. By street driving my track pads for a few day, the strong low temperature abrasive friction of track pads will wear down the transfer layer that is on the rotors. I then have a clean rotor surface on which to bed my street pads on. If you swap out to fast to the stock pads, they struggle to wear down the track pad deposit and will not bed properly.

[Absurdium]

@Powerslide

Quick report back on the brakes:

Brake feel was a lot better after putting down that transfer layer when I bedded in my pads. However, it seems like a lot of the transfer layer has been wore down as I drove mostly local roads this week. I'm guessing that brake vibrations may be more likely in the winter is due to this transfer layer being wore off easier than it would be in summer. So, if you end up doing heavy braking without a proper pad layer, it would definitely be easier to create heat spots. However so far so good on my end, no vibrations have come up. Might keep these pads after all.

[Powerslide]

Thank you for the update Absurdium - appreciate you sharing your experiences.

Just to add to this ongoing "database," when I had new rotors and pads installed in late January, a few days later I went out and did the Stoptech brake bed-in procedure listed on their website (and that CanAut3 posted in one of his replies). The brakes were smooth as glass both before and after the bed-in.

Because of the cold, I (like you in your last post) assumed that the transfer layer would wear off quickly in the winter months, so about a week later (and a couple of hundred miles later) I did another bed-in of the brakes. The brakes remained smooth as glass for the next week and 100-200 miles.

HOWEVER - we then had about 10-11 inches of snow here in the Chicago metro area - the salt trucks were out in force! Several days later, I began to notice an almost imperceptible amount of vibration on braking - to the point where I wasn't sure if I was imagining it or not. Over the next week or so (with intermittent additional snow and salting), the vibrations seemed to gradually increase, and I noticed a little bit of what appeared to be pad imprint on three of the rotors (even though I've always been extremely careful to avoid stopping completely on hot or warm brakes in the winter). The dreaded brake judder was back!!

Over the past few weeks in Chicago, we have not had any additional snowfall, thus no additional salt being thrown down onto the roads. Maybe it's placebo, maybe it's not - but I swear the vibration seems to be getting very gradually and very slightly better. I've been trying to wear down uneven deposits through normal street driving, with occasional, single hard stops from 70-40 or 20 mph, and then driving for a couple of minutes without any braking to try and get the pads/rotors back to ambient temperature (30-50 degrees F).

Last year I switched to my Pagid RS29's in February, did the above "normal" street driving with occasional, single hard stops, and the problem eventually disappeared completely by early April. I am now basically "experimenting" to see if I can accomplish the same result with cold street pads (even though they are not as abrasive as the Pagid RS29's).

Unfortunately, we are due for some snow later this week (which means more salt). I am becoming more and more convinced (rightly or wrongly) that road salt somehow creates a chemical reaciton in the pads, which in turn causes them to smear or transfer deposits more unevenly - which in turn would explain: 1) why brake judder never seems to come back until after the first 1-2 heavy snowfalls in December (and saltings of the roads) and 2) why once the judder is completely gone in April (whether after replacement of the rotors/pads, or by "wearing down the deposits" like I did in Feb.-April, 2017), it NEVER comes back again until late December/early January AFTER the first 1-2 heavy snowfalls and road saltings.

I'm no scientist and no engineer, but the consistency of these circumstances and their timing would make this pattern over the past 4 winters an incredible coincidence if my theory is not in fact scientifically correct.

Will keep you (and everyone else here) posted...

[gatorfast]

Originally Posted by Absurdium

Hello all. I recently purchased my F82 and have been very happy with it. Coming from an E92, the upgraded brakes were one of the highlights I was looking forward to. However recently, I noticed a slight vibration at high speed braking when the brakes are cold; as temperature warms up, it seems like the issue goes away, or is at least less noticeable. I did take a look at the rotors today and to my surprise, there are several pad outlines on the rear rotors; the front are fine.

I understand the characteristics of brake pads and rotors interaction and that 95% of the time, brake vibration are due to pad deposit. I also take care to cool down the brakes after any spirited driving or heavy braking to avoid leaving any deposits. I did initially bed in the pads when first getting the car but perhaps I was not aggressive enough.

After a quick search, I understand that many people have issues with this problem as there has been numerous threads on brake vibration, all seemingly due to pad deposits. The consensus appears to be that the pads are the issue as the stock rotors are quite robust. There seems to be some speculation that BMW has secretly replaced the pad material to prevent this issue from happening. However as you can see from the pictures, mine still left imprints, which if I'm not careful may turn into heavy deposits. I'll be bedding in my pads again later tonight to see that gets rid of them. Interestingly, I ran my finger through the imprints and they felt perfectly smooth.

Just wanted to see what has everyone else's experience been recently. Seems like the problem is not as common with the later build cars.

If this is still an issue, I may switch to stoptech 309s as they had good reviews as a aggressive street pad. So as a side question, anyone have any experience with stoptech 309s (now called stoptech sport) on the F8x platform?

Got any pics of the 220m wheels on your M4? Would be interested to see how they look.

[Absurdium]

Originally Posted by gatorfast

Got any pics of the 220m wheels on your M4? Would be interested to see how they look.

Yeah no problem. I posted some pics on this thread after my detailing (post #67). Because it's been so cold and wet here, haven't really taken any better pictures. To me they look decent when powder coated gloss black like mine. I'm actually not a big fan of 220M wheels. I'm only using them because they were my old set from my E92 and they fit fine in terms of offset and clearance so I thought why not

http://f80.bimmerpost.com/forums/sho...1427395&page=4