Warped brake discs... (Not on a blade...)

Discussion in 'Maintenance' started by Tonic, Jun 13, 2015.

  1. Tonic

    Tonic Active Member

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    Guys, I'm only registered on this forum, so hope you don't mind me posting this here.
    CBR600
    Got a slight vibration on my front brakes. I've stripped the callipers and all are working very well, so no problems there.
    I've seen there are companies out there who straighten discs. Do they actually straighten the disc or do they put full floating adapters on?
    Anyone any experience?
     
  2. sps170373

    sps170373 Moderator
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    Think you'll find they skim the disc flat again by machining, if the disc is near the lower thickness level it won't be possible to do
     
  3. Mike07

    Mike07 Active Member

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    Skimming discs was the thing years ago, the disks were as thick as a Dockers sandwich. But today with weight such a priority the tolerances are fine, as SPS has said may not be viable. By the time you've messed on I would suspect new discs may be the way forward. or if on a tight budget, Patten/ used.
    Good luck.
    Mike.
     
  4. Tonic

    Tonic Active Member

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    Ok guys, I've now run a DTI over the discs and the run out is 0.5 - 0.55 on both discs. I wouldn't have thought this much would cause a problem? What do you think?
     
  5. Mr OCD

    Mr OCD Well-Known Member

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    Anything more than 0.2-0.3 is going to cause problems ...

    I'm assuming there is no pad build up in the discs that can cause this issue?
     
  6. Tonic

    Tonic Active Member

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    No build up, I've just pressure washed the discs and bobbins to make sure there's no dirt preventing the disc floating.
    I'm getting a slight judder when braking at speed, but lower speed it grabs and releases, grabs and releases.....
     
  7. Mike07

    Mike07 Active Member

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    Had a very similar sounding problem on my mates Blackbird, he uses it through the winter and sometimes doesn't wash it off. anyway finished off with the pads sticking to the discs, He was experiencing similar things to you. He cleaned the discs, made quite a good job (I couldn't see any residue) and still had the problem.... I took it out and really gave the brakes a workout, getting them to fade state. It's okay now.
    I'm not suggesting you do the same, but just a pressure wash may not be enough, perhaps some brake cleaner and a pan scrub. before starting to chuck money at it.
    Mike.
     
  8. binned_it

    binned_it Active Member

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    If the disks are warped, you can try fixing with a hammer!
    Don't hit the disk (obviously), hit the buttons the disk floats - If done carefully, you bend the carrier, which forces the disk to run true.

    I've done that on a couple of bikes, including an R6, R1 and a bandit.
     
  9. Tonic

    Tonic Active Member

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    Well binned_it, laughed when I saw your post, so ordered some new discs. Then, thought......I wonder if it is possible to hammer them into shape.......1hr later, discs are to within 0.15mm!! Gonna hang onto the discs for the moment, see if I need them.
    Cheers fella
     
  10. binned_it

    binned_it Active Member

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    Glad it worked.
    It was a guy who raced bikes that showed me; I was sceptical too, but when he explained that the aim was to bend the carrier, and that the buttons the disk float on are very hard and can be safely tapped with a hammer, it made sense.

    It only has to be slightly out before it feels awful to ride, so it's not like you have to hammer 6 bells out of the disk to straighten again.
    Spin the wheel, watch the disk touch the pads, mark the bit that seems to be the problem, and carefully tap straight.

    I expected them to bend back or cause issues again, but it was never a problem. Happy days.
     
  11. Tonic

    Tonic Active Member

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    There wasn't really a problem till I went the IOM. I used an elastic band on the brake level to keep the front wheel fron moving on the ferry.
    I'm wondering if this caused the issue.
     
  12. binned_it

    binned_it Active Member

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    Maybe the carrier bent from that, rather than the disk actually warping under braking heat/load.
     
  13. DazKnowles

    DazKnowles New Member

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    That's interesting binned_it. I have exactly the same problem on my RR7! Braking at high speed vibrates the hell out the bike and low speed it "lurches" to a halt. She only has 13000 on her and had new discs 100 miles ago, I presume from the test cert it was warped discs but maybe not? She's back at the dealers under warranty and he confirmed the right disc is only 1mm out but the left disc is outside of tolerance.
     
  14. Tonic

    Tonic Active Member

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    1mm is far too much. You will feel it at 0.2. Mine are absolutely flawless now.
     
  15. DazKnowles

    DazKnowles New Member

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    Hi Tonic,
    so the hammer method worked then? I haven't said owt to the dealer. I'll let him and EBC replace them lol He mentioned it was 1mm out is all didn't say what the left one was:-( If it happens again I know what to try tho :)
     
  16. Tonic

    Tonic Active Member

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    Yeah, it worked a treat. When I'd finished, they were both about 0.15, I could still feel a very slight judder, but they've got better and better over the past 500 miles and now they are absolutely perfect. I now have a full set of EBC discs, pads and calliper seals I need to put on eBay (for my CBR609fx). I won't be doing it until I've upgraded to a blade tho....
     
  17. Wayne_R

    Wayne_R Active Member

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    I might give this a go. Got nothing to loose if you're going to buy new discs anyway.
     
  18. DazKnowles

    DazKnowles New Member

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    Just an update...EBC are replacing the discs. We'll see how it goes when I get her back. Thanks for the help and advice guys, appreciate it :)
     
  19. DazKnowles

    DazKnowles New Member

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    Turns out it's a manufacturer fault. Warped Disc Hubs. WTF!!!
     
  20. guyblade

    guyblade New Member

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    Ok so I have an rr4. Braking spot on at high speeds,but when say I'm pulling up to a junction fairly quickly,the last few metres brings the most incredible juddering if I keep the front brake at the same position. Would you suspect warped discs too?
     

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