carmudgeons.com  

Go Back   carmudgeons.com > Automotive Forums > Technical Superiority

Reply
 
Thread Tools Display Modes
Old 02-05-2020, 10:42 AM   #1
FC
Solving problems
 
FC's Avatar
 
Join Date: Oct 2003
Carmudgeonly Ride: '18 M3 ZCP, '13 LR4, '11 Miata
Location: Metro Boston
Posts: 22,112
Miata grinding noise on braking

The car has developed a sound just like the one you'd if the disks got pretty rusty and you then apply the brakes. Except that this noise does not go away. No sounds at all during coasting, even at low speeds. It only happens with the brakes on. It does not seem to impact braking performance at all either. Also, at times, after driving, it seems to improve, but then it returns.

IIRC, previous owner installed some AutoX-friendly, performance Hawk pads.

I put the car on the lift and pulled the wheels. Visual inspections shows plenty of pad life, and good looking disks. The rears have some uneven radial streaking, but nothing I could attribute the noise to. Unfortunately, the NC has crazy-expansive inner shields, providing a VERY limited view of the inside disc surfaces - particularly in the rear. I could not see rocks or anything like that stick between the discs and shields either.

I figure I can:

1) Remove the pads and better inspect inner disc surfaces and pads.
2) Even if 1) reveals nothing major I could just change the pads (and?) discs.
3) Let it go. This worries me because given the amount of life left and use fo the car, this could be a LONG while.

Any thoughts?
FC is offline   Reply With Quote
Old 02-05-2020, 10:59 AM   #2
Nick M3
Old Fart
 
Nick M3's Avatar
 
Join Date: Oct 2003
Location: Bethesda, MD
Posts: 9,849
Pop the calipers and check. I usually see greater wear on the piston side, so that's worth checking.

If it's good, reassemble and don't worry about it.
__________________
2006 GMC Sierra 2500HD 4WD LBZ/Allison
2002 BMW M3
1999 323i GTS2
1995 M3 S50B32, S6S420G, 3.91
1990 325is
1989 M3

Hers:
1988 325iX
1996 911 Turbo


Nick M3 is offline   Reply With Quote
Old 02-05-2020, 01:15 PM   #3
kognito
older fart than ZBB
 
kognito's Avatar
 
Join Date: Oct 2003
Location: On the road again
Posts: 8,091
Not saying this is what your problem is, but I once had something similar when a pad had actually come separated from its backing plate. First glance everything looked fine with plenty of disc life left. When I then pulled the caliper. . . . oops there it is, as the pad fell off
__________________
2017 GMC Sierra 1500 SLE
2016 Focus SE
kognito is offline   Reply With Quote
Old 02-05-2020, 02:21 PM   #4
FC
Solving problems
 
FC's Avatar
 
Join Date: Oct 2003
Carmudgeonly Ride: '18 M3 ZCP, '13 LR4, '11 Miata
Location: Metro Boston
Posts: 22,112
Yeah, I have a feeling I have no choice but to pull the pads and check them.
FC is offline   Reply With Quote
Old 02-05-2020, 05:10 PM   #5
Nick M3
Old Fart
 
Nick M3's Avatar
 
Join Date: Oct 2003
Location: Bethesda, MD
Posts: 9,849
Quote:
Originally Posted by FC View Post
Yeah, I have a feeling I have no choice but to pull the pads and check them.
It’s less effort to pull a caliper than popping the wheels off. I hope it’s still on the lift.
__________________
2006 GMC Sierra 2500HD 4WD LBZ/Allison
2002 BMW M3
1999 323i GTS2
1995 M3 S50B32, S6S420G, 3.91
1990 325is
1989 M3

Hers:
1988 325iX
1996 911 Turbo


Nick M3 is offline   Reply With Quote
Old 02-05-2020, 09:05 PM   #6
FC
Solving problems
 
FC's Avatar
 
Join Date: Oct 2003
Carmudgeonly Ride: '18 M3 ZCP, '13 LR4, '11 Miata
Location: Metro Boston
Posts: 22,112
I pulled the wheels to check it a week ago and have been driving it since. Either way it’s going back up.
FC is offline   Reply With Quote
Old 04-02-2020, 09:59 PM   #7
FC
Solving problems
 
FC's Avatar
 
Join Date: Oct 2003
Carmudgeonly Ride: '18 M3 ZCP, '13 LR4, '11 Miata
Location: Metro Boston
Posts: 22,112
Well, I think I found the problem. I took photos.

First, a photo of the rear right disk from the outside. Weirdly it shows some pitting which I've never seen before. I then took off the pads. Note the MASSIVE scoring on the inside pad. WTF? did a rock get stuck inside?! I held the pad against the inside of the disk and you can see that past the scoring, the disk wasn't even making contact with the pad and a decent section is untouched and rusted.

Then to the rear left. Disk looked a LOT better with hardly any of that scoring showing. Pads look a lot better as well, but again, there is a weird groove on the inside pad. A photo of the disk from the inside shows it looking awfully rusty considering it seems to have very little wear.

In both cases calipers look good and glide easily.

Oh, and the front brakes are excellent. For reference I took a picture of the outside and inside of the front right corner.

Finally a photo confirming the previous owner installed Hawk pads.
Attached Thumbnails
Click image for larger version

Name:	RR outside.JPG
Views:	46
Size:	283.9 KB
ID:	12635  Click image for larger version

Name:	RR pads.JPG
Views:	48
Size:	262.4 KB
ID:	12636  Click image for larger version

Name:	RR inside pad and disk.JPG
Views:	40
Size:	296.1 KB
ID:	12637  Click image for larger version

Name:	RL pads.JPG
Views:	38
Size:	266.4 KB
ID:	12638  Click image for larger version

Name:	RL disk inside.JPG
Views:	41
Size:	277.7 KB
ID:	12639  

Click image for larger version

Name:	FR brake.JPG
Views:	41
Size:	197.7 KB
ID:	12640  Click image for larger version

Name:	FR brake inside.JPG
Views:	39
Size:	199.9 KB
ID:	12641  Click image for larger version

Name:	Hawk pads.JPG
Views:	41
Size:	206.8 KB
ID:	12642  
FC is offline   Reply With Quote
Old 04-03-2020, 06:07 AM   #8
Nick M3
Old Fart
 
Nick M3's Avatar
 
Join Date: Oct 2003
Location: Bethesda, MD
Posts: 9,849
Well, i’d obviously replace the rear pads and rotors. Did you confirm that the pins move as well?
__________________
2006 GMC Sierra 2500HD 4WD LBZ/Allison
2002 BMW M3
1999 323i GTS2
1995 M3 S50B32, S6S420G, 3.91
1990 325is
1989 M3

Hers:
1988 325iX
1996 911 Turbo


Nick M3 is offline   Reply With Quote
Old 04-03-2020, 06:23 AM   #9
equ
Alphanumeric
 
equ's Avatar
 
Join Date: Aug 2005
Carmudgeonly Ride: 981S, 340i
Posts: 8,660
It took me a long time, but I've learned that if a bicycle, a motorcycle or a car make a funny noise. It's not to be ignored...
equ is offline   Reply With Quote
Old 04-03-2020, 08:05 AM   #10
FC
Solving problems
 
FC's Avatar
 
Join Date: Oct 2003
Carmudgeonly Ride: '18 M3 ZCP, '13 LR4, '11 Miata
Location: Metro Boston
Posts: 22,112
Quote:
Originally Posted by Nick M3 View Post
Well, id obviously replace the rear pads and rotors. Did you confirm that the pins move as well?
No doubt. I'm buying new disks and pads. Any harm in going with OEM pads in the rear with Hawk ads up front?

Pins glided smoothly on both calipers.
FC is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

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
Forum Jump


All times are GMT -4. The time now is 07:16 AM.


Powered by vBulletin® Version 3.7.1
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Forums 2003-2008, 'Mudgeon Enterprises - Site hosting by AYN & Associates, LLC