Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Where can I get my brake rotor straightened?

Discussion in 'Technical and Troubleshooting Torque' started by Kernel, Dec 30, 2011.

  1. Not sure if this is the right forum.
    The front brake disc on my 2010 DR650 is by no means worn out, but quite badly warped. I still have heaps of braking power, thing is I'm not sure for how long I'm still going to have it for. So I want to get a jump on this.

    Is there anywhere in melbourne where I can get it professionally straightened? As in, book a time, ride up, bum around for an hour or two, ride home with a straight brake disc, for less than $150? I believe it is a full floating disc.

    If I can't get it done for less than $150 I might as well grab a brand new disc and some brand new pads from Metalgear ($150 for the disc, $30 for sintered pads, + $15.95 post = just a smidge under 200), and get a hand putting them on.

    One other question, I had brand new Ferodo pads installed by 60 degrees motorcycles about 6-7000 km's ago. I don't do a lot of hard braking - will these pads still have plenty of life left in them to mate to a new disc (I doubt it) or should I get them replaced too?

    Thanks a lot folks!
  2. Better off getting it replaced as it might be worn and thin anyway. Rotors usually warp due to excessive heat and thinner worn rotors get hotter quicker.
  3. brake rotors can't be straightened as far as i know, it would weaken the metal along the fold, which worst case scenario would shatter, ripping out the brake caliper and potentially ripping the wheel off and/or gouging/snapping forks.
    extreme scenario i know, but that risk isn't worth it to me

    personally, i replaced my rear rotor without replacing the pads and it didn't bite properly, not to mention the striping on the rotor from teh uneven pad surface looking dodgy as. i have since replaced the pads (after maybe 100km, it just didn't feel right)
    so i would say replace them too
  4. Thanks for that mate, I'm pretty sure I know what I'm going to do now. I'll get the new metal gear disc and the sintered brake pads.
    I can see why the pads wouldn't bite properly - the uneven wear will make it so only part of the pads make contact with the disc. This might even out with use - but then your new rotor is a bit stuffed. Am I right or am I talking out of my arse? That said I wouldn't worry much about 100km.

    fark me I say 'I' a lot :-/
    Smee, I'm pretty sure I know why my rotor is warped, but I'm not going to mention the reason here.
  5. Planet Discs did mine. Still going strong thousands of km's later, and I give them an absolute caning.
  6. Yeah, only ever had them machined myself - since you're shaving them into straightness again, you need plenty of thickness left...
  7. You probably won't need new pads but a simple look see will tell you.
  8. I would prefer to replace a rotor than straighten it.

    There is the risk of weakening it and having it break - which would be bad - but the more likely outcome would be like what happens in cars, where people machine a warped rotor and it simply warps again as soon as it's used. A rotor that has warped due to heat and/or uneven heat, or sudden cooling in one spot (like a sharp splash of cold water while it was very hot) will be straight at one temperature and warped at another, and nothing you can do to it will fix that. Trying to fix it is just throwing good money after bad.

    Motorbike rotors of the type that are just a flat sheet of metal punched out are rather prone to this. The type that have a separate carrier and a set of buttons which hold the actual friction material are somewhat less prone, but it can still happen.

    I've managed to catch and reverse what felt like the start of a warp by cleaning the whole surface of the disk with emery cloth. If something splashes or spills on the disk which changes the friction at one point, (a splash of oil or grease off the road or from a puddle, an accidental or careless squirt of WD40 or chain lube...) that can cause a slippery spot, or a sticky spot. That will naturally heat up more, and if it's one side of the disk only (which it's likely to be) that can begin the warping process. By breaking up the glaze and cleaning the surface of the disk evenly on both sides, (and thoroughly de-greasing if you suspect something oily) you may be able to stop the downward spiral. It has worked well for me.
  9. Wrong. They straighten them first, then very lightly surface grind for a good finish.
    • Like Like x 2
  10. Well there ya go - thanks Roarin!
  11. Unless the properties of steel have changed in the last few years straightening the disc at any temperature below a couple hundred degrees should actually strengthen and harden the rotor
  12. See, now I'm confused again - I totally assumed there would be a fair few degrees involved in flattening something that thick?
  13. Depends. With enough leverage almost anything is possible. But given the shape of the warp probably isn't completely regular heating it will certainly be easier. Once heated, the property of the metal change is dependent on how long it remains heated and how it is cooled.

    I'm not sure where brake disc tech is at but I would guess the disc to be about .2-.3 carbon, so it may need to be heated but whether out gets above 730 celsius is the crucial question.
    • Like Like x 1
  14. Come on Lilley. Get it right. 723 degrees C for Low Carbon steels :) Yep, you would be correct that the straightening process may actually strengthen the metal a little. Depending on how it was manufactured ie hot rolled, drawn etc. As long as it hasn't gotten too close to its UTS (Ultimate tensile strength) then it should be fine. But I'm sure you know that already:)
    Actually, I'm pretty sure that heating the discs to straighten them would not be required at all. Not as if they are 20mm thick or anything. Generally only 5-6mm thick, so easily cold worked.
  15. I wouldn't use Planet Disks, he ripped me off big time. Just saying.
  16. Hmm, it looks like the rotor is going to be replaced.
    I will see how much the guy at planet discs wants to charge me and if it's like $120-150 then nah I may as well get it replaced, at least that way I can be confident that it's gonna stop the bike.
  17. Aw, go on. Nothing is too embarrassing for NetRider :D.
  18. Heard nothing but good things about planet discs till this post above, what happened?
  19. Lol you're an evil bastard.
    If you really want to know PM me but please promise me that you won't mention it to anyone.
  20. Is it something worse than leaving the disk lock on?