New pads and rotors -- "whirling" sound when braking?

[tgb1974]

Originally Posted by M3SQRD

You’re welcome

I always look forward to the switch back to summer performance tires! However, we keep an e92 M3 on summer performance tires so on a decent winter day with no salt on the roads, we can take it out for a fun few hour drive.

It has now been close to 1,000 miles since I had the rear brakes and rotors replaced. I also had the front brakes cleaned and the appropriate parts lubricated. What I have noticed is that the front of the car makes the whirring sound when slowing down even when not braking. The dealership foreman drove the car and inspected the brakes, and found nothing wrong. The brakes work fine but feel like there's some resistance. It's hard to describe. The dealer told me it's the winter tires, but that seems wrong to me.

Any thoughts?

[M3SQRD]

Originally Posted by tgb1974

It has now been close to 1,000 miles since I had the rear brakes and rotors replaced. I also had the front brakes cleaned and the appropriate parts lubricated. What I have noticed is that the front of the car makes the whirring sound when slowing down even when not braking. The dealership foreman drove the car and inspected the brakes, and found nothing wrong. The brakes work fine but feel like there's some resistance. It's hard to describe. The dealer told me it's the winter tires, but that seems wrong to me.

Any thoughts?

If it’s making noise when you’re not applying the brakes then that would likely point to something other than the brakes being the cause of the noise. Is this sound there at all speeds (interstates, highways, main roads, side streets, etc.) or only when slowing down? It might not be as loud/noticeable on highways because there are other louder noise sources so the tire/brake noise isn’t as noticeable. Try driving with the windows down for 20-30 min on different types of roads and speeds. If the sound is always there without brake use, I’d agree with the foreman - it’s the winter tires. We put winter tires on almost all of our cars and the first thing we notice is the significant increase in tire rumbling-humming sounds. Even brand new winter tires are much noisier than a well worn set of performance tires. The only check I can think of is to remove your winter setup, reinstall your summer setup and go for a drive over the same roads. Noise gone = winter tire setup. If the noise is not gone, then it could be the brakes, wheel bearing(s), etc. I expect the noise to go away (or be faint if the summer setup is well worn with feathering on outer and inner tread blocks). Winter tires, especially Snow and Ice versions, are louder than summer tires

[tgb1974]

Originally Posted by M3SQRD

If it’s making noise when you’re not applying the brakes then that would likely point to something other than the brakes being the cause of the noise. Is this sound there at all speeds (interstates, highways, main roads, side streets, etc.) or only when slowing down? It might not be as loud/noticeable on highways because there are other louder noise sources so the tire/brake noise isn’t as noticeable. Try driving with the windows down for 20-30 min on different types of roads and speeds. If the sound is always there without brake use, I’d agree with the foreman - it’s the winter tires. We put winter tires on almost all of our cars and the first thing we notice is the significant increase in tire rumbling-humming sounds. Even brand new winter tires are much noisier than a well worn set of performance tires. The only check I can think of is to remove your winter setup, reinstall your summer setup and go for a drive over the same roads. Noise gone = winter tire setup. If the noise is not gone, then it could be the brakes, wheel bearing(s), etc. I expect the noise to go away (or be faint if the summer setup is well worn with feathering on outer and inner tread blocks). Winter tires, especially Snow and Ice versions, are louder than summer tires

I really appreciate this thorough response. I will of course see what happens when I switch to summer tires and report back. However, I am beginning to think that there is a wheel bearing or brake issue as well. The reason I say that is because I can feel it in the brake pedal when pressing it down to break, particularly at very slow speeds. There’s a certain resistance, like something is dragging or rubbing against the wheel. Never felt it before I had the brake jobs done.

But then again the brake performance is awesome, so maybe I should just ignore it?

[M3SQRD]

Originally Posted by tgb1974

I really appreciate this thorough response. I will of course see what happens when I switch to summer tires and report back. However, I am beginning to think that there is a wheel bearing or brake issue as well. The reason I say that is because I can feel it in the brake pedal when pressing it down to break, particularly at very slow speeds. There’s a certain resistance, like something is dragging or rubbing against the wheel. Never felt it before I had the brake jobs done.

But then again the brake performance is awesome, so maybe I should just ignore it?

If it’s a wheel bearing it should make more noise while turning. Do you hear an increase in sound or a change in the noise as you corner to the left or right? Not sure what would create a dragging feeling? If there’s air in the line you’d get a softer pedal but nothing that would cause resistance or feel like dragging.

[tgb1974]

Originally Posted by M3SQRD

If it’s a wheel bearing it should make more noise while turning. Do you hear an increase in sound or a change in the noise as you corner to the left or right? Not sure what would create a dragging feeling? If there’s air in the line you’d get a softer pedal but nothing that would cause resistance or feel like dragging.

Thank you. Then let me ask this: what do the brakes feel like when the pads have not fully bedded in? What I'm trying to describe is that brakes, through the pedal, feel rough/grainy/grindy instead of smooth. But they only make the whirling sound, not a screech or a scary metal-on-metal sound.

So I'm back to where I started: is what I'm experiencing my brakes not being fully bedded in? Reminder: front brake pads/rotors are not new but the rear pads and rotors are about 800 miles new at this point.

Thanks so much for your advice and input!

[M3SQRD]

Originally Posted by tgb1974

Thank you. Then let me ask this: what do the brakes feel like when the pads have not fully bedded in? What I'm trying to describe is that brakes, through the pedal, feel rough/grainy/grindy instead of smooth. But they only make the whirling sound, not a screech or a scary metal-on-metal sound.

So I'm back to where I started: is what I'm experiencing my brakes not being fully bedded in? Reminder: front brake pads/rotors are not new but the rear pads and rotors are about 800 miles new at this point.

Thanks so much for your advice and input!

Pads that aren’t fully bedded may require you to more forcefully apply the brakes. However, your front brakes weren’t touched, and since they do the majority of the braking, you won’t really notice whether the rear brakes are fully bedded. If the front brakes were changed then you’d really notice whether the pads are fully bedded.

When the rear brake rotors and pads were changed, was the fluid changed? My guess is they did not change the fluid because the onboard computer was only showing rear brakes required servicing. If true, no new air is trapped in the braking system which is good. Were new oem rear pads and rotors used?

The front brakes do around ~65-70% of the total braking so, replacing only the rear pads/rotors, the braking feel should still be very similar to what you had with the worn rear pads/rotors. The brake pedal firmness may have increased a little due to the rear pistons being pushed back into the caliper when the new pads were installed. After the rear brake job, you noticed a loud whirling sound which has reduced with mileage but now you hear a similar noise but not with the brakes applied. Winter tires may be the cause of the new noise. The last picture you uploaded appeared to show a rear rotor with a good pad transfer layer + some remaining machining marks. AFAIK, nothing has been done to the front brakes before or after the rear brake job so there should be no change in front brake performance/feel. Do you know how much front pad thickness there is? When you feel the rough/grindy brake pedal, how heavily are you braking? If you try braking harder, does the pedal feel smoother? Depending on the type of winter tires you’re using, there can be significant tread squirm under braking and the abs may engage sooner/differently. Try braking harder and harder until you get the abs to engage. Pay attention to pedal feel and noise. Repeat this as many times as you need. Your rear brakes won’t be affected by this…

However, I don’t think what you’re experiencing is coming from the new rear rotors/pads. The feel and performance of your brakes before and after the rear brake job should be very similar because nothing was done to the front brakes and it’s the fronts that are doing most of the braking. The purpose of bedding-in pads is to get a uniform layer of pad material to transfer to the new rotor surface. This is important because it’s this transfer layer that wears away when the brake pads are applied (ablative braking). Without the layer, the pads will be removing material from the rotor surface (abrasive braking). The last picture of your new rear rotors showed a nice uniform layer of pad material on the rotor surface so your rear brakes are bedded. Without swapping pads around and/or in different calipers and/or installing summer tires, I’m not sure what else to try?

[tgb1974]

Originally Posted by M3SQRD

Pads that aren’t fully bedded may require you to more forcefully apply the brakes. However, your front brakes weren’t touched, and since they do the majority of the braking, you won’t really notice whether the rear brakes are fully bedded. If the front brakes were changed then you’d really notice whether the pads are fully bedded.

When the rear brake rotors and pads were changed, was the fluid changed? My guess is they did not change the fluid because the onboard computer was only showing rear brakes required servicing. If true, no new air is trapped in the braking system which is good. Were new oem rear pads and rotors used?

The front brakes do around ~65-70% of the total braking so, replacing only the rear pads/rotors, the braking feel should still be very similar to what you had with the worn rear pads/rotors. The brake pedal firmness may have increased a little due to the rear pistons being pushed back into the caliper when the new pads were installed. After the rear brake job, you noticed a loud whirling sound which has reduced with mileage but now you hear a similar noise but not with the brakes applied. Winter tires may be the cause of the new noise. The last picture you uploaded appeared to show a rear rotor with a good pad transfer layer + some remaining machining marks. AFAIK, nothing has been done to the front brakes before or after the rear brake job so there should be no change in front brake performance/feel. Do you know how much front pad thickness there is? When you feel the rough/grindy brake pedal, how heavily are you braking? If [...]

Here is a picture of the rear rotors about 1,000 miles post-replacement of the rear rotors and pads. The whirling sound is still present and I have to say has become very annoying. Brakes seem to function very well but the whirling sound and sensation that something is dragging (which feels like it’s coming from the front) makes me think there’s something up, maybe with the front calipers. Like the pistons are not retracting completely.

Recall that I had the front brakes thoroughly cleaned and lubricated about a month ago. They have been giving me this weird dragging sensation ever since. Dealership foreman drove the car and told me nothing is wrong but he did not perform a brake inspection. Thoughts?

[M3SQRD]

Originally Posted by tgb1974

Here is a picture of the rear rotors about 1,000 miles post-replacement of the rear rotors and pads. The whirling sound is still present and I have to say has become very annoying. Brakes seem to function very well but the whirling sound and sensation that something is dragging (which feels like it’s coming from the front) makes me think there’s something up, maybe with the front calipers. Like the pistons are not retracting completely.

Recall that I had the front brakes thoroughly cleaned and lubricated about a month ago. They have been giving me this weird dragging sensation ever since. Dealership foreman drove the car and told me nothing is wrong but he did not perform a brake inspection. Thoughts?

Rear rotors look fine and have a uniform layer of pad material/transfer.

Can you audio record the sound? Also, please take pics of the front rotors.

You’d see brake fluid all over a wheel(s) if a piston(s) weren’t retracting properly and you’d likely sharply move left/right under braking. If you’re doing your own brake work, I’d have you pull the front pads and look for odd wear patterns or tapering. I’d also have you flip pads in both front calipers (swap inner pads with outer pads). This might help isolate whether it’s a pad or caliper issue. Are your winter tires directional? If not, flipping the left and right side wheels may help prove/disprove it’s coming from the winter tires. Do you feel the same thing in the pedal when you brake hard, med or soft? Besides the noise and pedal/dragging feeling, how do the brakes work under a panic stop (extremely high pedal force)? Is the feeling in the pedal constant or intermittent? While braking, if you were to release the brake pedal at ~5 mph, do you hear nothing (excluding tire noises) or a constant noise or a periodic noise? When you say you had the front brakes cleaned and lubricated, what exactly was done? There’s really nothing to lubricate in a fixed caliper (pad retaining pins/guides?).

[tgb1974]

Originally Posted by M3SQRD

Rear rotors look fine and have a uniform layer of pad material/transfer.

Can you audio record the sound? Also, please take pics of the front rotors.

You’d see brake fluid all over a wheel(s) if a piston(s) weren’t retracting properly and you’d likely sharply move left/right under braking. If you’re doing your own brake work, I’d have you pull the front pads and look for odd wear patterns or tapering. I’d also have you flip pads in both front calipers (swap inner pads with outer pads). This might help isolate whether it’s a pad or caliper issue. Are your winter tires directional? If not, flipping the left and right side wheels may help prove/disprove it’s coming from the winter tires. Do you feel the same thing in the pedal when you brake hard, med or soft? Besides the noise and pedal/dragging feeling, how do the brakes work under a panic stop (extremely high pedal force)? Is the feeling in the pedal constant or intermittent? While braking, if you were to release the brake pedal at ~5 mph, do you hear nothing (excluding tire noises) or a constant noise or a periodic noise? When you say you had the front brakes cleaned and lubricated, what exactly was done? There’s really nothing to lubricate in a fixed caliper (pad retaining pins/guides?).

Thank you for your questions.

1. The car sometimes, but not always, jerks to the right while braking. It seems to happen randomly and I can't replicate it. The jerk to the right happens at both faster and slower speeds and while turning or not turning.

2. The whirling sound is still very loud and seems to come from the front of the car (front brakes and rotors were not replaced though I had them taken apart and cleaned). The brakes operate well but the whirling started in the front after that service happened. I am wondering if they reinstalled the pads on the opposite side.

3. There is no brake fluid anywhere.

4. Winter tires are not directional (just have inside/outside). I cannot rule out the possibility that the swapped the FR and FL tires when doing the brake cleaning work discussed above.

5. In terms of the front brake work done, I understand that they disassembled the brakes and thoroughly cleaned everything as well as the wheels themselves.

6. The brakes operate incredibly well during both ordinary, slow speed stops and panic stops. The whirling noise is really only evident when braking at slow speeds, but that might be because it is easier to hear.

7. The tire noise only started after I got the car back from the front brake service. While they are winter tires, I have had them for 5 years and they have never made this much noise. There is nothing obviously physically wrong with them (nails, etc.) and the pressure is all within spec (~33 psi). I was thinking that the causes could be that they swapped the FR and and FL so they are now wearing differently or while cleaning the wheel they inadvertently knocked off one or more of the balancing weights. As for the latter, I doubt that, as there is no wobble or shake at any speed.

Look forward to your thoughts.

I am taking the car to the dealer next week to swap in the summer wheels/tires and to perform a front brake inspection at the same time. Recall the last time I brought it to the dealer and the foreman took it for a test drive he said there was nothing wrong with the braking and my winter tires were just loud. The occasional jerk to the right tells me there is more to the story...

[M-SJ3]

I had brand new OEM "M" Rotors and Pads installed on my car yesterday and have noticed the exact same thing. A whirling sound (like a jet turbine) when using the brakes AND the same noise when driving without brakes applied (more pronounced at lower speeds but not as loud as applying brakes)

Also not sure if I feel a dragging feeling or it's in my head because of the noises.

I called the mechanic right away and they believe it's normal while the pads wear in. I'm a bit concerned with the noises heard while no brakes are applied and the dragging feeling. They did adjust the handbrake as well.

There was some squealing when first driving without brakes applied but that has since lessened.

Am I being overly cautious or is this normal for brand new cross drilled rotors/pads?

Should also note: had a brake flush with brand new fluid (Motul 660)

Pedal feels quite responsive

[tgb1974]

Originally Posted by M-SJ3

I had brand new OEM "M" Rotors and Pads installed on my car yesterday and have noticed the exact same thing. A whirling sound (like a jet turbine) when using the brakes AND the same noise when driving without brakes applied (more pronounced at lower speeds but not as loud as applying brakes)

Also not sure if I feel a dragging feeling or it's in my head because of the noises.

I called the mechanic right away and they believe it's normal while the pads wear in. I'm a bit concerned with the noises heard while no brakes are applied and the dragging feeling. They did adjust the handbrake as well.

There was some squealing when first driving without brakes applied but that has since lessened.

Am I being overly cautious or is this normal for brand new cross drilled rotors/pads?

Should also note: had a brake flush with brand new fluid (Motul 660)

Pedal feels quite responsive

I think you and I are experiencing the same thing. All indications are that the whirling/turbine noise is normal with new drilled rotors and pads. However, it has been over 1,000 miles since I had my rears done and the sound persists. I went through the bedding in procedure and yet the sound has not gone away.

So I am having the dealer inspect the brake system for any anomalies. I will report back when I have their findings. Thanks.

[tgb1974]

Originally Posted by tgb1974

I think you and I are experiencing the same thing. All indications are that the whirling/turbine noise is normal with new drilled rotors and pads. However, it has been over 1,000 miles since I had my rears done and the sound persists. I went through the bedding in procedure and yet the sound has not gone away.

So I am having the dealer inspect the brake system for any anomalies. I will report back when I have their findings. Thanks.

I should have added that I also am experiencing the "dragging" feeling and sound even while not braking. The dealer told me it is because my winter tires are loud. I know that is not the cause, however, because these tires have never made that sound before and the sound comes and goes with the same tires.

[M-SJ3]

Originally Posted by tgb1974

I should have added that I also am experiencing the "dragging" feeling and sound even while not braking. The dealer told me it is because my winter tires are loud. I know that is not the cause, however, because these tires have never made that sound before and the sound comes and goes with the same tires.

Please let us know how you go. I've only driven about 50kms (30 miles) since the install so extremely fresh. Have got the cross-hatched machine marks on the rotors still.

[M3SQRD]

Originally Posted by tgb1974

Thank you for your questions.

1. The car sometimes, but not always, jerks to the right while braking. It seems to happen randomly and I can't replicate it. The jerk to the right happens at both faster and slower speeds and while turning or not turning.

If it’s a problem with the alignment, wheel hub, strut/top mount or steering, the pull to the right would always be there. Have you tried repeating it on the same road and same lane where it’s happened before? I’m wondering if it could be road condition that could be a part of the problem?

2. The whirling sound is still very loud and seems to come from the front of the car (front brakes and rotors were not replaced though I had them taken apart and cleaned). The brakes operate well but the whirling started in the front after that service happened. I am wondering if they reinstalled the pads on the opposite side.

The rear brakes are definitely fully bed-in by now and, therefore, they shouldn’t be the cause of the noise and pulling to the right. The noise starting as the same time the brakes were serviced is likely a coincidence. Cleaning the front brakes should not create any issues with the brakes. Reinstalling the front pads in opposite sides of a caliper or even in a caliper on the opposite side of the car should not create a problem. People who track frequently, flip pads around and into different calipers to extend pad life and/or minimize pad taper. I do not believe if this was done it did not cause the noise and/or pulling to the right.

3. There is no brake fluid anywhere.

Good. Eliminates a potential cause/safety issue.

4. Winter tires are not directional (just have inside/outside). I cannot rule out the possibility that the swapped the FR and FL tires when doing the brake cleaning work discussed above.

If they’re not directional then they coude rotated side to side and see whether that improves things, worsens things or makes no difference. In the early 1990s I had my winter wheels and tires installed and when I got the car back, the steering wheel was rotated 10-15 deg off center. Put summer wheels and tires back on and the steering misaligned was gone but came back again when the winters were installed. Best we could come up with was the tires had a very uneven wear pattern that somehow caused the steering wheel to rotate which doesn’t make mechanically.

5. In terms of the front brake work done, I understand that they disassembled the brakes and thoroughly cleaned everything as well as the wheels themselves.

I can’t picture what they could’ve done that would cause the whirling sound or the pulling to the right. Other than the caliper pad retaining pins, they didn’t have to loosen anything that would cause pulling to the right. I also can’t think of anything that would create a noise that would persist for this long. Is this the same noise you first heard after the rear brakes were done or is it different, louder or anything else different that you recall? Did it go away for a while when the rear brakes quieted down?

6. The brakes operate incredibly well during both ordinary, slow speed stops and panic stops. The whirling noise is really only evident when braking at slow speeds, but that might be because it is easier to hear.

This suggests the brakes are functioning as designed even with the audible whirling noise as you’re slowing to a stop. I’m curious to know what happens when your summer wheels are reinstalled. I think this will shed some light onto what’s going on.

7. The tire noise only started after I got the car back from the front brake service. While they are winter tires, I have had them for 5 years and they have never made this much noise. There is nothing obviously physically wrong with them (nails, etc.) and the pressure is all within spec (~33 psi). I was thinking that the causes could be that they swapped the FR and and FL so they are now wearing differently or while cleaning the wheel they inadvertently knocked off one or more of the balancing weights. As for the latter, I doubt that, as there is no wobble or shake at any speed.

Wait, there was no noise between when the rear brakes were serviced and the front brakes cleaned? I thought the whirling noise started immediately after the rear brake service? I don’t recall you saying there’s a noise free period. Every set of winter tires, from winter performance to snow-ice, they’ve always been considerably noisier than summer tires and they louder and louder as they wear down/age. How long had the winter tires been on before the rear brake service?

Look forward to your thoughts.

I am taking the car to the dealer next week to swap in the summer wheels/tires and to perform a front brake inspection at the same time. Recall the last time I brought it to the dealer and the foreman took it for a test drive he said there was nothing wrong with the braking and my winter tires were just loud. The occasional jerk to the right tells me there is more to the story...

I look forward to reading your comments after the summer wheels and tires are installed.

[tgb1974]

Originally Posted by M3SQRD

I look forward to reading your comments after the summer wheels and tires are installed.

MAJOR UPDATE:

The car was at the dealer for the last day or so to have the brakes inspected and the summer wheels/tires installed. The dealer's top M mechanic personally handled the inspection. He found absolutely nothing amiss with the brakes, rotors, their installation or the control arms, though he did note the whirling noise when braking.

But, after he mounted the summer tires/wheels, the whirling sound completely disappeared, as did basically all of the weird feel I was experiencing when applying the brakes. The brakes are now smooth and dead silent. Obviously I am thrilled to death about this, but I am still confused.

1. I can accept that the winter tires were generating the non-braking noise I was hearing. It is now warmer here in the Chicagoland area and the tires themselves are date-coded 2019 (though they have plenty of tread left on them) so maybe they are showing their age.

2. However, I do not understand how switching back to the summer tires affects the brake noise (creating the whirling sound) and feel. The dealer really did not have a good explanation for this. I thought that maybe the service station that cleaned up the front brakes a month or two ago may have reinstalled the wheels in a weird or incorrect way, but I'm not sure how that's even possible. The dealer is going to remount and rebalance the winter tires, so we'll see (in amount 7 months) if that makes any difference.

Interested in any thoughts/speculation anyone has on this. Thanks!

[M3SQRD]

tgb1974

I’m glad to hear the noise and brake pedal feel issues are resolved!

I’m not surprised to hear it was due to the winter tires based on my own experience with them. I’d have your alignment checked ASAP. If your alignment is off, it could have been wearing one tire, or one side, differently from the others so your issues continued to worsen as you drove more on the winter setup.

Remember, it’s ultimately the tires that stop a car. So what the tires are doing as you brake can be felt in the brake pedal. Winter tires have much taller, softer tread blocks as well as more smaller blocks (increase channeling and ability to dig into snow) so they squirm around a lot under braking. If, for example, the left and right fronts are wearing differently due to the left-right alignments being different, the car may want to pull to one side while braking or it’s a combination of tire wear and alignment.

A five year old tire is likely still fine if it’s been stored properly, has sufficient tread and is showing no signs of dry rotting. Rubber tends to harden with age and it results in loss of grip. As long as the tires aren’t showing any of these signs then they’re likely safe to use. There’s no real “expire by” date on a tire; however, the older they get, the lower their performance window.

[robbo mcs]

Some tires, with particular tread patterns, can definitely make noises like you describe while braking. I've experienced it with some semi-slick race tires

[mapster37]

There is a BMW service bulletin that describes the exact noise you are concerned with. It's 100% completely normal operation. It should get less noticeable with more miles driven.

[M-SJ3]

Originally Posted by tgb1974

MAJOR UPDATE:

The car was at the dealer for the last day or so to have the brakes inspected and the summer wheels/tires installed. The dealer's top M mechanic personally handled the inspection. He found absolutely nothing amiss with the brakes, rotors, their installation or the control arms, though he did note the whirling noise when braking.

But, after he mounted the summer tires/wheels, the whirling sound completely disappeared, as did basically all of the weird feel I was experiencing when applying the brakes. The brakes are now smooth and dead silent. Obviously I am thrilled to death about this, but I am still confused.

1. I can accept that the winter tires were generating the non-braking noise I was hearing. It is now warmer here in the Chicagoland area and the tires themselves are date-coded 2019 (though they have plenty of tread left on them) so maybe they are showing their age.

2. However, I do not understand how switching back to the summer tires affects the brake noise (creating the whirling sound) and feel. The dealer really did not have a good explanation for this. I thought that maybe the service station that cleaned up the front brakes a month or two ago may have reinstalled the wheels in a weird or incorrect way, but I'm not sure how that's even possible. The dealer is going to remount and rebalance the winter tires, so we'll see (in amount 7 months) if that makes any difference.

Interested in any thoughts/speculation anyone has on this. Thanks!

Glad to hear everything has been sorted for you!

Just thought I would update everyone on my situation also and hopefully help others in the future.

The whirling sound has significantly reduced over the past couple of days including the sound when not applying the brakes (basically non-existent now).

I've done a total distance of 300kms (180 miles) - about 30% of that was some spirited twisty driving with hard stops on/off.

I've included photos of the front / rear brake wearing - the fronts have almost eliminated the machine marks whereas the rears seem like they need more time.

I have a theory that the noise heard while not on the brakes may have been some caliper/pad drag while the contact surfaces even out - happy for people to chime in on this one!

My tyres are Michelin PS4S - have been consistent in between brake changes.

[M3SQRD]

Originally Posted by M-SJ3

Glad to hear everything has been sorted for you!

Just thought I would update everyone on my situation also and hopefully help others in the future.

The whirling sound has significantly reduced over the past couple of days including the sound when not applying the brakes (basically non-existent now).

I've done a total distance of 300kms (180 miles) - about 30% of that was some spirited twisty driving with hard stops on/off.

I've included photos of the front / rear brake wearing - the fronts have almost eliminated the machine marks whereas the rears seem like they need more time.

I have a theory that the noise heard while not on the brakes may have been some caliper/pad drag while the contact surfaces even out - happy for people to chime in on this one!

My tyres are Michelin PS4S - have been consistent in between brake changes.

Your issue is 100% due to the installation of new front and rear pads & rotors. He had this same issue which improved over 500-700 miles. His persisted for a longer time because he had only the rear brakes serviced. If he’d had front and rear done together, the bedding of the front pads would have more quickly helped fully bed the rear pads. He did not have rotor noise while just driving, it would start as he’s coming to a stop with the brake pedal applied. In addition, he had a constant whirling noise. Early on after having the rear brakes done, he had the shop foreman go for a ride and he said it was the winter tires causing the whirling noise. I agreed with the shop foreman at the time. However, he didn’t believe the tires could be the cause because he felt it in the brake pedal. Finally, after putting his summer wheels on, the noise, the pulling and feeling of dragging in the brake pedal, all went away. In your case, it’s either try re-bedding your pads more aggressively and/or wait another 500-700 miles for the noise to dissipate as the front and rear complete the bedding-in process and transfer of pad material. Your rotors appear to have very little pad material transferred to the braking surface. Also, it’s common for rotors with cross-drilled (or manufactured) holes to make an audible whirling sound as the pad goes over the series of holes in the rotor surface.

[M-SJ3]

Originally Posted by M3SQRD

Your issue is 100% due to the installation of new front and rear pads & rotors. He had this same issue which improved over 500-700 miles. His persisted for a longer time because he had only the rear brakes serviced. If he’d had front and rear done together, the bedding of the front pads would have more quickly helped fully bed the rear pads. He did not have rotor noise while just driving, it would start as he’s coming to a stop with the brake pedal applied. In addition, he had a constant whirling noise. Early on after having the rear brakes done, he had the shop foreman go for a ride and he said it was the winter tires causing the whirling noise. I agreed with the shop foreman at the time. However, he didn’t believe the tires could be the cause because he felt it in the brake pedal. Finally, after putting his summer wheels on, the noise, the pulling and feeling of dragging in the brake pedal, all went away. In your case, it’s either try re-bedding your pads more aggressively and/or wait another 500-700 miles for the noise to dissipate as the front and rear complete the bedding-in process and transfer of pad material. Your rotors appear to have very little pad material transferred to the braking surface. Also, it’s common for rotors with cross-drilled (or manufactured) holes to make an audible whirling sound as the pad goes over the series of holes in the rotor surface.

Yeah, I feel alot more at ease now.

What would you recommend? Is it better to intentionally bed the brakes in through aggressive start/stops or just drive normally until this process occurs naturally? This is my first time driving a car with brand new rotors.

Does the current state of my rotors look OK - any signs of incorrect driving / bedding?

Cheers

[M3SQRD]

Originally Posted by M-SJ3

Yeah, I feel alot more at ease now.

What would you recommend? Is it better to intentionally bed the brakes in through aggressive start/stops or just drive normally until this process occurs naturally? This is my first time driving a car with brand new rotors.

Does the current state of my rotors look OK - any signs of incorrect driving / bedding?

Cheers

It’s best to bed-in the brakes to ensure you don’t over heat them, for example in an emergency stop, and the brakes decelerate the car properly. Other concern is if you get the brake pad too hot too quickly, you can glaze the brake pad (make the surface look polished like a mirror) and then the pad doesn’t stop or perform as well. There’s two types of braking - ablative and abrasive. Ablative is the way a properly functioning brake system should work. It starts by bedding-in the brakes which basically means you’ve transferred a uniform layer of brake pad material to the surface of the rotor. Once this happens, the braking actually occurs between the brake pad material and the pad material on the rotor surface that’s getting wore off, hence the name ablative braking. Abrasive braking is when there’s no transfer layer and if the pad is aggressive enough, say a track or high performance pad material, it actually wears away the surface of the brake rotor similar to a brake lathe and, thus, the name abrasive braking.

So to properly bed-in your brakes:

1. Drive and brake moderately (say ~30-40% of brake capability) for about 15-20 minutes to get good temperature into the rotors and pads.

2. In quick succession, brake from 50 mph to 20 mph with ~70-75% braking capability, repeat 3-4x times. Accelerate quickly back to 50 mph and perform the next braking attempt until you’ve done it 3-4x.

3. Same as #2 but get up to 65-70 mph and brake with around 90-95% brake capability without engaging abs to 20 mph. Again repeat 3-4x times in quick succession. Don’t wait more than five minutes before completing step 2 and starting step 3.

4. Drive on the highway, freeway, etc. for 10-15 min without applying the brakes (or if you do, try to keep it moderate and release the pedal as quickly as you can). This step is done to ensure the brakes cool uniformly and to allow the pad material to cure uniformly onto the rotor surface. If you followed these steps, your rotors will have a slightly darkish grayish color on the rotor surface (see below).

If you’re comfortable with braking without engaging abs, steps 2 and 3 can be combined into 1 step: essentially step 2 but get up to 70-75 mph and brake with 90-95% brake capability (no abs engagement) down to 20 mph. Repeat in quick succession 5-6x and then proceed to step 4 for the cooldown/curing. It’s a lot simpler to do than it might sound.

The earlier pics you posted of the rotors looked fine (no hot spots/bluing of the rotor surfaces) but they lacked any pad transfer.