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How to tell if brake disks need replacing?

Discussion in 'Motors' started by Over Clocker, 19 Apr 2010.

  1. Over Clocker

    Man of Honour

    Joined: 17 Oct 2002

    Posts: 9,695

    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.


  2. Janesy B


    Joined: 19 Apr 2008

    Posts: 25,564

    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: 19 Apr 2010
  3. jamoor


    Joined: 22 Jun 2005

    Posts: 8,824

    Location: Nottinghamshire

    try taking it to a garage.
  4. NightShadow

    Wise Guy

    Joined: 19 Oct 2002

    Posts: 1,925

    Location: Welling/London

    Have you check bot sides of the discs? Discs which look fine on one side can be completely FUBAR on the other as I found on my rear discs.
  5. Clarkey


    Joined: 18 Oct 2002

    Posts: 18,182

    You checked both the inner and outer pads? On the 320d the inner pads wore out completely but the outer ones still looked fine.
  6. Sounds more like you have a small stone stuck in there.
  7. dannyjo22


    Joined: 9 May 2005

    Posts: 30,815

    Location: Cambridge

    Haha hopefully next time you post a thread for help or advice everyone will just post the same back to you or take it to a pc repair shop ;)
  8. smr


    Joined: 6 Mar 2008

    Posts: 8,575

    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?
  9. mike66uk


    Joined: 2 Feb 2010

    Posts: 153

    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.
  10. jamoor


    Joined: 22 Jun 2005

    Posts: 8,824

    Location: Nottinghamshire

    TBH with something like brakes, it's probbably best to get a professionals opinion on the matter.
  11. Gaijin


    Joined: 18 Feb 2003

    Posts: 8,554

    Location: Brighton/West Wicklow

    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.
  12. Lopéz

    Man of Honour

    Joined: 17 Oct 2002

    Posts: 27,921

    Location: LE9/OTK

  13. Janesy B


    Joined: 19 Apr 2008

    Posts: 25,564

    Brakes are about the easiest thing to do on any modern car.
  14. The Edge


    Joined: 18 Oct 2002

    Posts: 5,730

    Location: Birmingham

    I'd say that's about right.
  15. Gaygle


    Joined: 7 Nov 2004

    Posts: 15,297

    Location: East of England

    Yeah that's great! I think Bugatti charge roughly 10 times that for just ONE disc.
  16. Jamous

    Wise Guy

    Joined: 7 Jan 2007

    Posts: 1,074

    Location: Scotland

    Post up some pics and we'll give opinions
  17. St0rmer66


    Joined: 31 Oct 2004

    Posts: 4,550

    Location: Harrogate, North Yorks

    As an indication.. 2 front discs on my motorbike are over £300! :eek: .
  18. Scania


    Joined: 25 Nov 2004

    Posts: 24,684

    Location: On the road....

    I had an old Astra Belmont that was actually worse than that - when the garage took the wheel off, what little was left of the disc fell away! :o:o:o
  19. Liampope


    Joined: 8 Jan 2010

    Posts: 3,380

    Location: Bedford/Stavanger


    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 :)
  20. Booner!


    Joined: 29 Sep 2005

    Posts: 9,129

    I'm looking at £600 for just discs alone :D