Machining Break Disks

Discussion in 'Wheels, Tyres, Brakes & Suspension' started by M3 SHAM, Aug 18, 2011.

  1. M3 SHAM

    M3 SHAM Active Member

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    My front and back brake discs are starting to show a littlt bit of a lip maybe 2-3mm and I was looking into getting them replaced. My 05 C180k comes with sports pack so has the larger vented and drilled disks which have are more pricey than the standard disks.

    So I have heard people talking about getting the lip on their break disks machined and wondered if anyone had done this before instead of buying new disks? What are the pros/cons? and how much should it costs to do all 4?

    Many thanks in advance
     
  2. bunter6

    bunter6 Active Member

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    I have heard of this before myself but to be honest if theres one area you dont want to be looking after the pennies too much it's your brakes. Maybe it's better now but in years gone by this was definately not a reccomended practice.

    I mean your talking around £220 from eurocar parts for 4 Eicher discs & Pagid pads. I'm sure GSF is probably aroudn the same.

    You could probably do even better on eBay but then your possibly taking a chance on disc quality.

    Cheers

    Mark
     
  3. moonloops

    moonloops MB Club Veteran

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    What difference will machining the lip make considering it is an area that the brake pads don't touch ?
     
  4. Alps

    Alps MB Club Veteran

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    E55 brake disks were 37.50 + vat each.... yours cant be more than that! for that sort of money id buy new
     
  5. DRBC43AMG

    DRBC43AMG Hardcore MB Enthusiast

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    Lips on discs are a sure sign that they are wearing out. I would measure the thickness of the remaining disc and see if it is close to or below the minimum recommended thickness. Below = DANGER and needs immediate attention and change. Why? I know the consequences of an exploding disc :eek: but I survived without any harm except to the car. Good brakes may one day save your life, so don't be too skimpy on the cost. Oh and buy some good quality items. Even if a bit more expensive they end up being cheaper on the long run :thumb:
     
  6. jeffwebb

    jeffwebb Hardcore MB Enthusiast

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    Where from please, Regards, Jeff
     
  7. moonloops

    moonloops MB Club Veteran

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  8. OP
    OP
    M3 SHAM

    M3 SHAM Active Member

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    When I check with ECP they wanted just shy of £300 for OE quality disks and pads all round. This is due to the car being fitted with the sports pack (Bigger disks drilled and vented) To be honest i think i will proberbly opt for the new disks and pads all round, was a just a little intrigued why people skim break disks and if it was a viable option?
     
  9. grober

    grober MB Club Veteran

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    Buy new discs
     
  10. OP
    OP
    M3 SHAM

    M3 SHAM Active Member

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    I believe this price is for standard disks, Not the uprated sport option disks which my car requires.
     
  11. moonloops

    moonloops MB Club Veteran

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    I picked the sports version but do double check with them :thumb:
     
  12. Sp!ke

    Sp!ke Administrator Staff Member

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    I vote for skimming disks too, no need to replace disks at all if within minimum thickness. On performance vehicles with expensive disks this is a very common thing.

    Last time I just ground off the lips with an angle grinder didnt take long but you need to be careful.

    You might want to give Procut a call and ask if there's someone local to you with their system.

    On-car brake lathes, quickly resurface the brake disks
     
    1 person likes this.
  13. jaymanek

    jaymanek Authorised Forum Sponsor Authorised Forum Sponsor

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    sport pack discs are £50 each from the dealer... Its not worth skimming them.

    However it is perfectly safe to skim them if you go to someone who has the correct equipment. The minimum thickness is stamped on the disc.
     
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  14. DRBC43AMG

    DRBC43AMG Hardcore MB Enthusiast

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    First time I've seen a skimming machine. Nice and simple set-up
     
  15. markjay

    markjay MB Club Veteran

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    As above...

    There are 3 issues to look for on discs: even surface, minimum thickness, and warping.

    A disc can be machined in order to restore the smooth surface as long as it does not go below the minimum thickness.

    In the olden days machining was the norm, and you could usually do this once or twice before having to replace the discs..

    However over the past 20 years labour cost shot up dramatically, and with current labour rates the cost difference would be minimal as the bulk if the expense will be for removal and refitting. So you might as well just change them....

    Incidentally, I did enquire about machining some years ago when the dealer told me I need new discs on my previous car, but they just said 'we don't do that any more Sir'.
     
  16. bunter6

    bunter6 Active Member

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    That price is for the sport discs & pads.

    Obviously it appears skimming has come a long way from what I used to know but I'd be interested in what people actually charge for skimming. I cant see it being less that £15 a disc as I assume they are going to charge an hours labour for 4 discs.

    If you were gonig to do this in concert with new pads then I dont see you saving a whole lot over buying new really.

    Personally I'd stick with your new kit all round plan.

    Cheers

    Mark
     
  17. Cabe

    Cabe Hardcore MB Enthusiast

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    If you are the kind of guy (like I am) that hoards every receipt (short of petrol) spent on the car for resale, which would you rather see in the sheaf of knowledge handed over when you buy a car?

    New Disks and Pads all round.

    or

    Skimmed the disks to squeeze some more life out of them.
     
  18. jaymanek

    jaymanek Authorised Forum Sponsor Authorised Forum Sponsor

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    If you can find a garage that has a machine that bolts to the hub you will save the labour on removing the discs...only then would it make financial sense.
     
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  19. markjay

    markjay MB Club Veteran

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    Oh yes... I remember those....

    BTW, I also remember when they use to have wheel balancing machines that balance the wheel while on the car.
     
  20. balge

    balge Hardcore MB Enthusiast

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    The presence of a lip is not necessarily due to the disk being worn out, it can be crud building up, try a file on it, then use a micrometer or calipers to measure the thickness - compare to makers spec...then you will know - or else you could just guess....

    Both my 124s have had lips on the disks, when the disks are worn too thin I replace them, if its just crud I go round them with a file and dress them.

    Personally I might surface grind them, not 'turn' them, that implies a lathe to anyone with an engineering background, although the Procut 'on car' system seems perfectly viable - properly done it could result in less run-out than a poorly fitted new disk...


    cheers!
     

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