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03-21-2020, 09:56 AM | #1 |
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Brake issue between 50-20 deceleration
Hi folks, been trying to solve this for awhile .
I have a harsh vibration(no squeaking) sensation when doing medium to hard deceleration on my Z4m ONLY from 50 mph to 15mph. (Above and below it sounds normal)The problem definitely worsens the heat you put on the brakes. I seem to sense it for front and back , and the brakes smell smoky/hot after only medium levels of braking. (All of this street driving not track) below are things I've tried to address it. 1. Change front rotors to oem 2. Change front pads to new oem 3. Change fluid 4. Change to hawk pads (properly bed) 5. Adjust hand brake in case it was just touching when rotors got hot. Nothing seems to be working... could I need rebuilt calipers or bearings ? But it seems like it's not drawing any of those symptoms (front and back/relatively even brake distribution etc) Any help would be extremely helpful , been trying to address this for the past 5-6 months . Thank you ahead!!! |
03-22-2020, 12:53 PM | #2 |
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My similar issue was resolved by making VERY hard stops from 60 mph (about 5 times); this cured my braking vibration; this was recommended to me and I was skeptical but it worked; the counsel I received on this site (and from a tech) was that Z4M rotors rarely warp (which is what I thought was causing the braking vibration).
You have gone way beyond something as elementary as my hard stops, but wanted to offer this info. Once your resolve it, update this thread - we're anxious to know what it was!
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03-22-2020, 07:36 PM | #3 |
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My go to suggestion when one complains of brake shudder on a BMW is to check your control arm bushings. Rotors rarely warp. Even a small amount of deflection will cause what feels like warped rotors.
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03-23-2020, 12:17 AM | #4 |
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I will chekc the control arm. I just changed the rotor so I agree unlikely rotor warp. Any folks have thoughts on this thread statement I dug up?
"It's also not uncommon for the sliding mechanism on the OEM single piston to get fouled/seized up. They also make a rather horrible and disconcerting grumbling sound after a while of hard use" Sounds a lot like my problem. A grumbling.. Any idea what mechanism he is referring to in the calipers? |
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03-25-2020, 07:35 PM | #6 |
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So I'll be getting new rotors and pads as the rotors seems to wearing uneven.
Also took out piston to caliper and there seems to be some corrosion. Shop cleaned that up but now I have massive brake squeal from the back on the hawk pads. Going to have fcp euro warranty the rotors. See attached pics... In terms of wheels, what should I be checking for?? |
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03-27-2020, 12:48 PM | #9 |
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When you first changed rotors did you change the rotors and pads at the same time? Or did you do the rotors first and pads second? If so how many miles were put on the car between the rotor and pads replacement?
Have you confirmed the caliper guide bushing have free movement? Any corrosion?
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03-27-2020, 12:59 PM | #10 |
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Pads and rotors done at the same time. That said I feel like the piston in the caliper being messed up damaged the rotors very quickly? Maybe only put 2k miles on pads/rotors.
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03-30-2020, 04:05 PM | #11 |
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I think the issue may be in the calipers with a piston sticking and dragging the brakes, since you're noticing a brake smell after a normal drive.
If you have an infrared thermometer to check brake temps after a normal drive, you can narrow it down if one side is significantly hotter than the other. If it's really bad, putting your hand CLOSE will allow you to feel the heat difference (don't touch recently used brakes unless you really want to burn yourself! ) When you replaced the pads and compressed the calipers, did any of them fight you being pushed in? Luckily, the calipers are an easy rebuild if necessarily! If you do need to rebuild them, be sure to replace the rubber bushings for the sliding pins as well.
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03-30-2020, 04:10 PM | #12 |
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This is what I saw after opening the caliper
All 4 pistons had some kind of corrosion on them. After cleaning up and installing it was better but not completely gone. Will I have to replace my rotors from damage after just getting them? |
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03-30-2020, 04:29 PM | #13 | |
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Quote:
Re-bed your brakes following proper bed in procedures after reinstall and see how they feel. If you have a judder afterwards, may need to warranty the rotors
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2017 M2 - Camber Hubs, MPE, and some other goodies 2006 Z4M - Epic Tune / Eventuri CAI / Euro Headers / Stromung / FA 500 / AS SSK / Arc 8s 2004 Z4 3.0i - Gone, but not forgotten! |
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04-15-2020, 05:08 PM | #14 | ||
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Quote:
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04-15-2020, 06:48 PM | #15 | |
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Oh no!
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This is just incredible - we feel your pain and frustration in attempting to ID and correct this. Dare I ask....what are your thoughts on the next steps?
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04-29-2020, 10:02 AM | #16 |
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Ugh finally solved 2 weeks ago, had a technician go in there with a. Fine tooth comb and clean up everything . Atleast I have a all new set of brakes now
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04-29-2020, 10:16 AM | #17 |
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What ended up being the culprit? I replaced my rotors, pads, fluid and rebuilt the front calipers due to a slight sticking and pad deposits issue last summer - I feel your pain!
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05-01-2020, 10:07 AM | #18 |
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I have noticed that same "grumbling" when slowing down with light braking. My rotors and pads are old, so I figured it was about time to replace. But this is a really good post to remind me to go and check the piston movement and clean off and inspect everything thoroughly during replacement.
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