How to tell if brake disks need replacing?

Man of Honour
Joined
17 Oct 2002
Posts
9,711
Location
Retired Don
Hi guys,

Over the past week by front brakes (BMW E46 330i) have started to squeal a bit. I've checked the pads and there is loads let on them, as they were replaced about 4 months ago or so. How could you tell if the disks are worn down, and would this cause squealing?

It does sound like a more metal on metal sound rather than just dust, and there was some scoring on one of the disks.

Cheers,

Mal
 
Caporegime
Joined
19 Apr 2008
Posts
26,249
Location
Essex
The squeaking will be the pad, not the disc and some copper slip on the back of the pad should sort that out. You should replace the disk if it has a large lip, corrosion or scoring.
 
Last edited:
Soldato
Joined
18 Oct 2002
Posts
18,299
You checked both the inner and outer pads? On the 320d the inner pads wore out completely but the outer ones still looked fine.
 

smr

smr

Soldato
Joined
6 Mar 2008
Posts
8,753
Location
Leicestershire
don't mean to sabotage thread but i just got 2 new front tyyres fitted at ats and was told my front discs are wearing thin... got quoted 140 quid for them... this a good deal?
 
Associate
Joined
2 Feb 2010
Posts
153
Sounds more like you have a small stone stuck in there.

I had this problem. Squealing noise coming from one wheels. Took the pads off and turns out there was a small bit of grit stuck between the pad and the disc, a quick sand down of the pad and clean up, put it back in and problem solved.
 
Soldato
Joined
18 Feb 2003
Posts
8,612
Location
Brighton/West Wicklow
TBH with something like brakes, it's probbably best to get a professionals opinion on the matter.

They are noisy, it's not like they aren't working.

Squealing is usually due to lack of lubed shims, aggressive pads, lack of pads :D or pad movement in the caliper.

Lube the shims first before you do anything more drastic.
 
Soldato
Joined
8 Jan 2010
Posts
3,379
Location
Bedford/Stavanger
Don't be such a fanny.

If a disc looks like this, you've had your money's worth.

http://www.connieanddicks.com/images/real-bad-rotor.jpg

:eek::eek:

On second thoughts - naaaaah - there's plenty of life left in that! All they need to do is unstick the probably seized inner piston, and seize up the outer with some fine grit or something. Then they can do the same miles again on the other side of that disk. Simples :)
 
Back
Top Bottom