Brake wobble - dodgy discs?

OE disks or aftermarket? OE is normally a better choice.

You won't see anything wrong by eye anyway. Mount the disks back up and check them with a dial gauge.

Once they've warped and released whatever stresses were locked in the material a light skim will normally cure it for good unless a sticking caliper is causing the problem by overheating them.

Was going to suggest a sticking caliper.

Disc thickness variations may be caused by disc wobble caused by an incorrectly fitted disc or a faulty flange/hub. this will be okay for a while after fitting new discs, then develop. So your problem is quite possibly the way the discs were fitted or the hub.

The only way forward is to get some new discs, fit them and check the runout.

useful brake info here, inc. your exact problem:

Thanks all, you've been a great help.

I think I'll have a look around and see if I can get the wobble machined out of the discs, seeing as they're virtually brand new. Any idea where I'd be able to get this done? The 'brake & clutch services' section in my copy of Yellow Pages just lists a load of Kwik- Fits and the like.

Might not be worth it. I'll bet even OE-quality discs are cheap, and at least they won't be seized on.

Sorry, scratch that - I seem to have found a few on Google. Last question(s) - is there any way of finding out if it's a dodgy hub causing the problem other than taking it to a garage? I'd rather cure the cause of the problem rather than ironing out the symptoms.

Would replacing the hub be the sort of thing the average home mechanic could do?

discs are so cheap it is not worth machining them (at least not if you have to pay)

With a new disc fitted and bolted on, the runout should be checked using a dial gauge. Correct as needed. Whether you can change a hub ? Impossible to say, but if you are unsure in advance then get a garage to do it, just in case.

The hub is unlikely to be damaged: just make sure it is clean, and then check the disc run-out as mr cheerful suggests.

How would I correct the runout? The disc doesn't bolt into the hub as such, and is just held in place by the wheel. I can't see any obvious way of making any adjustments to correct a runout....?

You need to use the wheel nuts perhaps with some bits of tubing to temporarily ensure the disc is clamped properly in place without the wheel.

There is no adjustment that can be made other than skimming the disc. On something like a Focus this would be uneconomic. The wear limit is only

Usual cause of runout is rust particles on the hub when the disc was fitted. They need to be wire brushed until shiny!

If the hub itself is not damaged, and the seating area of the hub and disc are clean, any runout can only be a faulty disc.

Chris

Hence why you have to have a new disc to make the measurements with. The mounting surface and the disc MUST be scrupulously clean, the disc must be bolted up tight to the hub, either use the wheel nuts plus some big washers or put the wheel on and measure the inside face of the disc. It is extremely unlikely that a new disc (particularly if it is a Ford disc, which are not expensive) will have any significant runout, therefore if the faces are clean and if you have a new disc and you still have excess runout then there is only one cause and that is the hub itself, which is quite common on fords, even the general car shops stock them. The disc runout maximum is

Thanks guys, you've been a real help.