Brake disc skimming

[ForzaGilles]

I've just fitted a pair of the vented front discs to my car and it appears one or both of them are warped. Can anyone recommend a firm in the midlands that will skim then?

[anonymous-user]

I would get them off and make sure they're mounted accurately before assuming that they're warped. Warping isn't as common as is often thought and if they're new, it's more likely to be mounting or some other issue.


Skimming them on car will solve the issue of course. Soham, Cambs. too far? Disc skimmers.com has a good reputation.

Edited by anonymous-user on Wednesday 20th July 14:32

[ForzaGilles]

REALIST123 said:

I would get them off and make sure they're mounted accurately before assuming that they're warped. Warping isn't as common as is often thought and if they're new, it's more likely to be mounting or some other issue.


Skimming them on car will solve the issue of course. Soham, Cambs. too far? Disc skimmers.com has a good reputation.

Edited by REALIST123 on Wednesday 20th July 14:32

Ok thanks.They're not new discs, but the mounting is fine. New wheel bearings have also just been fitted.

I saw that place in Soham, but it's a bit far for me really, i'm in Rugby. There's a place in Northampton that will hopefully be able to do them, although they're concerned about ground clearance of the car.

[was8v]

More likely pad transfer material, not warped discs.

Have a read:

http://www.mossmotors.com/SiteGraphics/Pages/brake...

http://www.stoptech.com/technical-support/technica...

[DCL]

Whether you believe that article, or not, the route cause of 'warped' discs comes from them being fitted with excessive run-out.

The mechanism is that the pads are in contact with one section of the disc longer than the other and this leads to uneven wear (to the thickness). If the run-out exceeds the normal 'knock back' of pads, then this may happen very rapidly. Even when you correct the run-out, the uneven wear is still present. They may, over time, even up but sometimes the easiest option is to replace them.

It's VITAL that the disc and hub mating surfaces are spotlessly clean when assembled and that bearings are in good order.

Edit to add: If new bearings have been fitted, I'd be looking at run-out on the hub surface too. Could be a badly seated bearing race.

Edited by DCL on Wednesday 20th July 16:43

[ForzaGilles]

was8v said:

More likely pad transfer material, not warped discs.

Have a read:

http://www.mossmotors.com/SiteGraphics/Pages/brake...

http://www.stoptech.com/technical-support/technica...

I'll have a read, thanks.

I meant to say in my previous post that they're NOT new discs.

[ForzaGilles]

DCL said:

Whether you believe that article, or not, the route cause of 'warped' discs comes from them being fitted with excessive run-out.

The mechanism is that the pads are in contact with one section of the disc longer than the other and this leads to uneven wear (to the thickness). If the run-out exceeds the normal 'knock back' of pads, then this may happen very rapidly. Even when you correct the run-out, the uneven wear is still present. They may, over time, even up but sometimes the easiest option is to replace them.

It's VITAL that the disc and hub mating surfaces are spotlessly clean when assembled and that bearings are in good order.

I don't really want to pay in excess of £300 for two new discs, not when the current ones are barely worn.

The bearings are brand new.

[DCL]

I've just added to my post about the bearings. Are these AP/ Caterham discs?

[DCL]

ForzaGilles said:

I meant to say in my previous post that they're NOT new discs.

OK there's a clue. Any run-out on the car they where fitted to will have transfered to the disc. Stick with them, they may sort themselves out. (as a side note it's always a good idea to keep discs in the same orientation to the hub)

[ForzaGilles]

DCL said:

I've just added to my post about the bearings. Are these AP/ Caterham discs?

If it was bearings related, the vibration would be constant and not just when you press the brake pedal, surely?

Yes, AP/CC 4 pot calipers and vented discs.

[ForzaGilles]

DCL said:

ForzaGilles said:

I meant to say in my previous post that they're NOT new discs.

OK there's a clue. Any run-out on the car they where fitted to will have transfered to the disc. Stick with them, they may sort themselves out. (as a side note it's always a good idea to keep discs in the same orientation to the hub)

Thanks, I hope you're right!

[DCL]

ForzaGilles said:

Yes, AP/CC 4 pot calipers and vented discs.

They're VERY strong and I'd be very surprised if there was anything seriously wrong with them. If you are able to check the run-out (you can hold a pencil in a stand against the surface of the disc while you rotate it) and it's OK (no more than a few thou), I'd just keep using them and see if they improve.

[SimonRogers]

You dont need to pay that much for a pair of vented discs.

You can get a pair for £170.00

[one eyed mick]

Used to get similar probs on new fords try rotating the disc 90 degs either way , it some times works incredibly well . Personaly would never fit s/h discs no matter where they came from

[ForzaGilles]

SimonRogers said:

You dont need to pay that much for a pair of vented discs.

You can get a pair for £170.00

Are they AP discs, Simon?

[SimonRogers]

No. But they are identical! Sold many many sets. All in stock for next day delivery.

Have a look at my site.