Speed wobble

[ianwanstead]

hi all ...not sure if anyone has heard of this before...got a 2001 XKR convert.

after about 8 months started to get a speed wobble through the steering wheel and floor pan from 60mph upwards...smoothing out at about 90.

after sending it to my local jag dealer and another specialist, they couldnt find anything..started to become a bit paranoid, but also started to hate driving it.

eventually i put the car in for a 60000 service and the manager test drove with me and suspected the front break discs.

replaced the front discs and all was ok...for a while and now after 6 months on the new discs..its back...not as bad, but back...

i also have started to get breaking vibration, so its back into the garage to get the front breaks checked again.

i have replaced the front tyres already, balanced etc and i do seem to get the square tyre syndrome after leaving the car for a week undriven, but i still believe there is an underlying problem with either the balancing or the front wheels ...got the original 18" wheels with standard tyres..

do i need a specialist balance?....some wieird pressures settings.. new wheels?

any ideas would be appreciated..

best regards

ian

[mike020150]

A downside of the pleasantly sensitive steering on the XK8 is that all the suspension components, including tyres, wheels and discs have to be in top condition to avoid nasty sensations finding their way to the driver. Like all automatics, it is easy to cook a set of XK8 discs by sitting in gear with your foot on the brake pedal after a series of relatively heavy brakings, eg on the M1 any Friday evening. So, don't discount the possibility of needing yet another set of discs without measuring their run-out. If the discs are within tolerances, tyres are another common problem for heavy cars which sit around a lot. The tyres go out of round and it gets progressively harder to get them back into shape with use. I recall reading one Jaguar service bulletin which suggested that where tyres are suspect, test run the car for up to 250 miles(!) before writing them off and replacing them. These are probably among the most common problems along with the usual issues of worn ball joints and wheel bearings. Mike.

[doug424]

Hello Ian,
I suffered a speed related wobble on my 98 XK8, all the wheels were balanced fine and the tracking at the front was good. None of the tyres had unusual wear patterns and the car would drive just fine.
The wobble would start at about 65 to 70 mph and remain at all speeds above that.
The problem was traced to an excentric tyre at the rear of the car by a mechanic at a tiny French village garage. He put the tyre on a balancing machine, disabled the safety guard to leave it open and stood well back. The deformity was easy to see with the wheel and tyre spinning. I put on the spare (I carry a full size spare) and no wobble.

Doug Barrass, Ashford, Kent.