BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
Go Back   6Post.com | BMW 6-Series Forum > BMW 6 Series Forum > General 6-Series Coupe, Convertible, and Gran Coupe Forum

Post Reply
 
Thread Tools Search this Thread
      12-04-2021, 01:40 AM   #1
NeoBMW
Enlisted Member
United_States
1
Rep
31
Posts

Drives: 2016 640GC M
Join Date: Dec 2012
Location: SoCal

iTrader: (0)

Whistling noise from front brakes after replacement

I’ll try my best to give as many details as possible to make some sense out of this frustrating issue so pls bear with me.

2016 640i GC with 47k miles. Bought it 2 yrs back with 33k on it as I don’t drive it as much since I work from home. About few months back , when braking and especially at around 50-60 mph , I would get a violent front end and steering shake. Took it to my usual local non dealer bimmer shop and they suggested it might be a bent rim or bad tires BEFORE they look into front rotors and pads which probably is the issue, but they suggest I should still check the rim as well. Interestingly the Front left had a bent , got it fixed , tires are fairly new , but issue persisted same so I took it back to the shop.
$1200 later - new brakes and rotors and brake fluid with air filters. Shakes gone and all was well.
Then about a month ago (2 week after the brakes were changed) I started to hear a loud whistle noise as the car came to a stop. It’s loud and happens as I am about to apply full brake e.g. coming to stop at a red light then the sound just stops as the car stops.. Same sound when in drive thru, where there is lots of stop and going. It’s loud and whistles embarrassing and annoying.
Took it back to the shop and was told to drive for more miles as the brakes need to settle with new rotors OR maybe the calipers might be bad (???) I didn’t like the answer since I truly blv there is something else wrong either with parts or labor work. But I still tried as suggested.
It’s been about 1000 miles since the brake/rotor change and frankly the sound has gotten worse. Also it happens when the breaks “warm up” as it won’t do it when I take the car out of driveway or short drives.

What could be the issue? Next week I am taking it back to the same shop and will have to have a come to Jesus convo with them to FIX this.

Should I get a second opinion ? What should we be checking? Shoddy work , bad parts?

Thanks !
Appreciate 0
      12-04-2021, 09:32 AM   #2
Opie55
Major
455
Rep
1,458
Posts

Drives: '15 650i Convertible
Join Date: Apr 2018
Location: US

iTrader: (0)

The first answer to your question "what could be wrong?" is that you go to that shop. Seriously. A shake that only happens when braking is not a bent wheel or bad tire. Then when you have a squeal afterwards to even suggest the calipers is somewhere between incompetent and planning to rob you.

Brake squeal can happen two places - between the pad and the disc, and between the caliper/piston and the metal backing plate of the pad. The former is from rubbing, the latter is from a very high frequency vibration. That is why there is brake caliper grease - to cushion all those contact surfaces. Did this shop bother to use it or just slap new pads in? Who knows. Reason number 4,657 why I do my own work.
Appreciate 0
      12-04-2021, 11:21 AM   #3
Opie55
Major
455
Rep
1,458
Posts

Drives: '15 650i Convertible
Join Date: Apr 2018
Location: US

iTrader: (0)

And I will add that it is very unlikely to be bad parts per se, although you don't say what brand parts they used. What usually causes a squeal between the pad and the disc surface is "glazing" - a buildup of pad material on the disc surface. You can usually see that just by looking.

If it were my car, or just somebody asking me to check their car - what I would do is remove the pads, clean up every surface on the calipers really good, grease every possible contact surface - the clips that go inside the hollow caliper piston, the pad backing plates, and where the metal "hooks" on the outside of the pads slide on the calipers. Then, absent any obvious glazing of the rotors, I would pass each pad over some sandpaper laid on a flat surface a couple times just so you are starting with a fresh pad surface and to eliminate that as a source of the noise.

Very rarely squealing can be caused by something totally weird. My daughter's Audi had what you are describing so I set out to do what I just described when a small finish nail fell out of a front caliper. Who knows how it got stuck in there.

Finally, there are instances where a certain brand of pads will squeal for no obvious reason, and not on every car. Swapping to different pads will cure it.
Appreciate 0
      12-04-2021, 03:57 PM   #4
NeoBMW
Enlisted Member
United_States
1
Rep
31
Posts

Drives: 2016 640GC M
Join Date: Dec 2012
Location: SoCal

iTrader: (0)

Thank you @opie55 incredibly
Informative. Im taking it in on Monday and discuss these options with them. I also youtubed this issue and it seems its very common on BMWs.
Appreciate 0
      12-05-2021, 09:26 AM   #5
Opie55
Major
455
Rep
1,458
Posts

Drives: '15 650i Convertible
Join Date: Apr 2018
Location: US

iTrader: (0)

Quote:
Originally Posted by HallandTuning View Post
Right! very common
Not sure why BMW brakes would squeal more than other brands of car. The only real variable is pad material, and BMW does not make its own pads. There are currently 3 BMWs in my family and none have had any brake squeal, and I've read most every post on this forum for nearly four years and that is not a common refrain.
Appreciate 0
      12-05-2021, 06:54 PM   #6
Alpine650
Private First Class
50
Rep
177
Posts

Drives: 2017 BMW 650i xDrive Vert
Join Date: Mar 2020
Location: MA

iTrader: (0)

NEO I would suggest to the shop since you spent $1200 in other repairs before they did the brakes as you suggested, perhaps this time they check the brakes before moving on to additional repairs. If they can find a scalpel inside a patient after surgery it is within the realm of possibilities that they may have missed something. Maybe even just a little cleanup as Oppie suggests.

I feel your pain. I spent $2400 on straightening 6 wheels, balancing something like 12 wheels, and 2 new tires. Then they said the "issue" is the torque converter - but it is within tolerance. Still drives like shit to this day.
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 06:12 PM.




6post.com
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2022, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST