I recently changed the car to a newer X350, an X358 Sovereign, and have noticed brake judder when braking fairly lightly from about 50 mph upwards. Clearly there is some disc run-out, yet an inspection of the discs shows them as almost new, as are the pads. In fact they look like Jaguar OEM ! However, having bought the car from a dealer in London, I have no invoice from the previous owner as to when these might have been fitted. It seems to me to be a shame to throw away such parts. I would have no hesitation in replacing if they were well worn and grooved, but I do hate waste !

I have read of a brake disc lathe machine that faces up the discs whilst they are still on the car and takes out the run-out, (actually reduces it to around 1 thousandth of an inch). The machine is made by Pro-cut and is recommended by many car makers, but is I believe installed in all Porsche dealerships. You'll see Jaguar are on the photo of car maker logos on this web page : -

http://www.brakelathe.co.uk/why-skim-discs/drivers/

Does anybody on here have any experience of having brake judder removed by this machine or similar ? There are about three shops near me and I am thinking of having this job done in the near future.

 

9 times out of 10 the rotors do not need refacing, they simply need traces of residual pad material removed.

It's normal practice here to go over the rotor surface with a rotary sanding pad when swapping pads.

 

On vehicle brake lathes are required dealer service tools for
many makes. Including Jaguar.

That means the equipment must be on premises for the dealership
to retain its franchise.

Measuring disc thickness variation is done with a micrometer and
is simple but takes some diligence on the part of the operator.

Measuring axial runout is done with a dial indicator.

The minimum thickness for the discs will be stamped on the disc,
or you can refer to the Jaguar documentation.

 

Could be a sticking caliper piston.