Wheel wobble

[KevNoble]

A cautionary tale. I replaced my front discs and pads (and brake fluid) a few weeks ago. Following that, I noticed a wobble through the steering wheel at around 70mph which became very irritating as I spend most of my driving on the M4. I see from "Google" that this is not an uncommon problem on the XF (and many other cars). To investigate the problem, I bought a dial gauge off the internet for £20 to measure hub, disc and wheel runout. On checking the runout on the discs and hubs, I found that the hubs were near perfect, but that the front left disc had about 0.09mm with a definite high and low point: I therefore suspected that something was between one side of the disc and the hub. When I originally changed the discs, they were pretty difficult to separate from the hubs as they had rusted on and although I had removed most of the rust on the hubs, it turns out I had not been thorough enough! When I removed each disc in turn, I found I had missed some rust on the inner lands of the hub that support the disc, particularly on the front left. I spent quite some time carefully polishing off the remaining rust with fine emery paper. On replacing the discs, runout was reduced to near zero and hey-presto, the wheel wobble is now gone.

The wheel hubs are only about 5inches in diameter, whilst my wheels are 19inch, so with tyres are over 24inches: hence any tiny imperfection caused by foreign matter trapped between the hub and disc is magnified by the relatively large diameter of the wheel compared to the hub to cause significant runout at tyre and hence wheel wobble.

In summary then, when changing discs, be meticulous on cleaning up the hubs before fitting the new ones. Alternatively, if your garage has just changed them and you notice a wobble, you know who to blame!

[Rictus]

Thank you Kev, that is excellent advice for us all to file away

You must be both pleased with yourself for having resolved the issue but irritated that you missed a trick the first time. But your pain is our gain

[oldtimer]

Hi Kev,
I'm pleased that you have resolved your Wheel Wobble problem.

I have repeatedly written words on this subject until I am blue in the face. This subject can be found in the S type section under "Brakes" which is a blow by blow account of the procedure to follow. The need for a run check on fitment using a DTI (Dial Test Indicator) is emphasized repeatedly.

I get a little paranoid about folks being "ripped off" with "slap dash" work and two or three months later when the wobble or judder manifests itself the blame is put down to "crap" discs.

Having made discreet enquiries at a number of both Franchised and Independent repair organisations, they admit to not doing a run out check in that it takes too long.

For those unable to replace discs themselves and rely upon a repair organisation I would suggest they ask the very question about run out checks and for the resultant run out figurers achieved.

Kev, you have obviously learned the hard way but at least by raising the subject yet again some folks might learn. It's also nice to read that you are doing the work yourself

Oldtimer

[Banker56]

My XF has developed a brake judder causing the steering wheel to wobble. This happens at any speed over 30mph. The brake pads and discs were replaced by the prior owner in 2019, approximately 9000 miles ago. They are in good condition and the car stops ok but it judders every time.

I would appreciate ideas from anyone reading this. Do I need to do a wheel hub test, should I have the brakes cleaned and refitted? Not an expert in this area and I don’t want to spend money unecessarily.

[rosemary]

This is common to many cars not just Jaguars. It's a combination of vented discs warping due to heat build up during braking and shoddy replacement of discs by time pressured mechanics in "Approved " workshops. Checking "Run Out" is vital as mentioned in previous posts. Discs do warp after some use but the most common cause is rust on the hub faces and not properly cleaning it off..