I've got AP 4pots on 305mm bells and rotors that have a wobble on when braking, can these be skimmed and if so how much would a light skim cost and where is best to have it done in Leicester/ shire?

 

prob worth getting them skimed, ebc near me will do them, i think its Ł15-Ł20 and if it still hasnt hepled then maybe look at some new disks as im sure one alone will cost alot more than getting them all skimed

 

Skim them on the car in case its the hub face not the disc etc

 

U mean measure the run out on the hub. U can't skim the disc on the hub ?

 

Yes you can. My Mondeo had a hub that wasnt quite straight and I had two sets of discs skimmed on the car

 

Try skimming the discs. Probably cost Ł30-Ł40

 

Check out the science behind warped discs - skimming them can be a false economy. When the disc warps you get a hot spot compared to the rest of the disc - because of the concentrated build up of heat the composition of the metal in that area changes. Therefore you can skim the disc flat again but the area of the original warp will re-warp when it gets hot. Might be better just spending out on new discs.

 

Bang on the money!!
Disc "warpage" is caused by DTV, disc thickness variation, it happens to all to some degree or other, you don't need to shell out on pricey overpriced AP replacements though, there are others.
It is certainly worth checking the run out of the hub face, and using a dial gauge on the disc when fitted to get the run out a slow as possible, you have a choice of 4 different positions on the hub alone.
tabetha

 

The theory may say that but in practice I've had several sets of discs skimmed and had a lot of use out of them.

 

Fair play, you may have just had a build up of brake pad deposit which needed taking off, but if a disc is properly warped and the properties of the metal has changed across parts of the disc it will never be worth the effort of skimming it.

 

I didn't I had a hub damaged by mongs putting the bearing in badly. It would always warp a new disc which I'd then get skimmed and it would last until worn out without warping again. Just a road car tho so not seeing temps like on a hugely fast car or track toy

 

Are they definately warped? There was a guy on MLR a few years back who seemed to be warping discs alot. It turned out his pads were leaving deposits on the discs which would clean off with some hard braking.

 

It's been a slight rub on the rear disks since the AA man towed my car with the hydraulic handbrake on. It's just getting more severe, though I have done 2000+miles on them since. I will have them measured and skimmed first, worth a try for the price

 

i can get them skimed for you if you want

 

new ones everytime. never cuts costs on brakes or steering. cost cutting costs lives!!
check it is the disks thst are warped first though

 

Thanks fella, I will get a runabout car first

 

Cant see a problem skimming a disc providing theres enough meat left in it afterwards?

What would compromise safety?