Warped brake disc. Can anybody help?

[lllN30lll]

if that's what you call it? Bought some galfers off a member, they arrived and fitted them, thing is anything over 70mph if you pply the brakes the whole front end shakes badly including the mirrors. Checked everything, wet n dried the discs, new SBS pads, torqued disc bolts to 19nm, even when I spin the disc on the stand you can hear the difference in 1 part of the disc.

sent the seller pictures of the disc marked in 4 equal places and the difference between each section, but he's still not happy, apparently "they were straight when my mechanic took them off, and they were straight when I sent them, you must have warped them"







So what can I do? Can I get the disc refaced or whatever it's called in order to get them straight?

 

[Godzilla]

No idea how st straighten them, but if there is a member on here selling dodgy stuff should he not be named to stop it happening to others?

 

[lllN30lll]

he's not bothered mate, keeps saying it's my fault. I warped them apparently so I've got no leg to stand on.

 

[lllN30lll]

PS I managed to warp them in 2 miles of fitting them apparently. Go figure.

 

[yam-andy]

I have refaced car discs using a lathe before but never done bike discs, considering your using a dti to check run out I'm guessing you have some engineering backround or know how? It looks like a 10 micron clock so Looks like you have around .4mm runout there? Only thing I can think of is if you can split the actual disc from the carrier? (Don't know correct term for this) and using a surface grinder and a magnetic table grind flat on both sides, I'm guessing you would have to remove around a minimum of .5mm at least to achieve this, and i would prob do both discs to keep things the same, not sure what minimum thickness is?? It may be possible to heat them and some how straighten, but speaking as precision tool grinder I'm saying the only way you would be to correct this would be to regrind.

 

[bananaman]

Why was he selling them? Discs dont warp within 2miles. Have you double checked yr fitment?

 

[andybarsblade]

Make sure the discs are offset side to side mate

 

[andybarsblade]

http://www.youtube.com/watch?v=rSPloB_KNG4

Found this if it helps?

 

[Niven770]

There will be a tolerance for distortion and for thickness this would let you know if you can skim them or not. Personally I wouldn't skim on a motorbike.

Wasn't it posted on this forum that there was an issue with Galfer, it think if you trawl you will find it ?


Why were they sold on after 2 miles of use ?

Davy

 

[fatbob]

yup i remember the warped disks post ( galfers as well i think)
I don't think taking 0.5 off on a lathe would be a big issue depending on the starting thickness.
If ya like i know of a tool shop in Fenton , the owner is a pal of mine.
I can ask him if he can skim it for you , might cost you a couple of quid.
PM us if you need help with it

 

[lllN30lll]

Why was he selling them? Discs dont warp within 2miles. Have you double checked yr fitment?

He was putting his bike back to standard, the deal was I send him my standard discs and £150 and I get his galfers.

Double and triple checked everything, absolutely every bolt on the front end it torqued up to the manual. Checked the face of the wheel where the disc sits, checked the bearings, checked the bolts, replaced the pads. Everything. Now I'm stuck with discs and I can't put my originals back on because he's got them.

 

[Shug]

You've tried freeing off the buttons on the disk yes? Not sure if I'm teaching granny to suck eggs here, but that's a floating disk design. Measuring runout on the disk face when it's in the carrier won't achieve much as the disk is designed to have lateral movement to help braking effort, pad centralisation and metal growth when it gets hot (it actually stops them warping, as the disk face isn't rigidly bolted to anything, which lets it grow when hot).

Hose them in brake cleaner and try to rock the disk side to side, then, go out for a ride and try to get them hot. You might find them freeing off - they might have stuck in an off-centre position in transit. Might even take some taps with a soft faced mallet (FFS don't whack them, just a tap to free when they are soaking in brake cleaner)

 

[yam-andy]

Did you have any luck with these?

 

[lllN30lll]

Fatbob has offered to get them refaced for me mate. Tried very other route, seller is ignoring me now.

 

[yam-andy]

In my opinion these need to be ground not skimmed on a lathe, we are busy at work unless I may have been able to do them for you, there is a company called blackshadow
www.blackshadow-uk.co.uk, they specialise in manufacturing brake discs and offer a rebuild regrind service replace rivots etc, seem to know there stuff and rates look reasonable to, defo worth a look mate.