I have a Jaguar XJ super sport swb and was wondering if anybody knows what the symptoms would be for a bad drive shaft bearing mount/support... Thanks

 

A bad center support bearing should present the same as in any other car. Howling sound at speed. Vibration commensurate with vehicle speed only, not engine RPM. For example, if the vibration is felt at 2000 RPM in 7th gear at 65mph, it should be felt just as strongly in any other gear holding the same speed- remember the rotation of the driveshaft is always directly proportional to rear wheel speed. The vibration may be strongest at a certain speed where the frequency matches the natural resonant frequency of the vehicle. Check your rear CV boots as early X351 models had accordion shaped flex boots that are known to fail (updated boots are smooth and not accordion shaped). My stock boots have been ripped for at least 50K miles and haven't presented any problems, but a failed CV axle may present similar symptoms.

If you successfully diagnose and replace this yourself, most will recommend preloading the new CSB by mounting it slightly offset to preload the rubber bearing cradle (this may already be accounted for in the FSM service procedure). Also, while you're doing this job you might as well replace the rear diff pinion seal- they're known to fail and weep.

 

Thank you for that good information, I should have explained what it's doing as well. When you accelerate or decelerate you can feel a little clunky feeling and I was thinking it was that but maybe not. Don't have any vibrations or anything like that. Definitely feels like it's in the drivetrain for sure

 

A common failure point on the X351 it the gearbox mount, which can cause symptoms like the ones you describe.

The JLR part number is C2D38505.

 

Good point about the transmission mount. I would also check the motor mounts as those 3 things wear together.
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Yeah sounds definitely like a possibility for sure. Feels like something's moving around in the drivetrain....