03-21-2024, 05:36 PM | #23 | |
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Any thoughts?
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03-21-2024, 06:48 PM | #24 | |
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03-22-2024, 08:50 AM | #25 | |
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But then again the brake performance is awesome, so maybe I should just ignore it?
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03-22-2024, 09:28 AM | #26 | |
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03-22-2024, 11:20 AM | #27 | |
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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!
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03-22-2024, 12:39 PM | #28 | |
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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? |
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04-04-2024, 07:56 AM | #29 | |
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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?
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04-04-2024, 09:17 AM | #30 | |
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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?). |
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04-10-2024, 10:07 AM | #31 | |
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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...
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04-11-2024, 04:58 AM | #32 |
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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 |
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04-11-2024, 11:08 AM | #33 | |
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So I am having the dealer inspect the brake system for any anomalies. I will report back when I have their findings. Thanks.
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04-11-2024, 11:14 AM | #34 | |
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04-11-2024, 08:19 PM | #35 | |
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04-11-2024, 09:09 PM | #36 | |
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04-13-2024, 10:15 AM | #37 | |
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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!
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04-13-2024, 11:03 AM | #38 |
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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. |
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04-14-2024, 04:32 AM | #39 |
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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
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04-14-2024, 06:51 AM | #40 |
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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.
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04-14-2024, 05:19 PM | #41 | |
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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. |
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04-14-2024, 07:43 PM | #42 | |
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04-14-2024, 09:04 PM | #43 | |
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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 |
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04-14-2024, 10:32 PM | #44 | |
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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. |
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