Hi: I hope someone can help. My XJS has 133,000 miles on it and I am hearing a wherring sound coming from what I think is the rear axle area, It is loudest at around 45 mph. I checked the fluid in the differential and that was ok. Any hints on how I can pin this down would be very helpful. Thanks

 

try jacking up the rear end and spinning the tire on each side to look for a different sound or feel

 

When spinning the wheel, if you can hold the spring with your bare hand, you should be able to sense the friction transmitting though the spring.

The wheel with the good bearing would not transmit any vibration through the spring.