Seeing so many posts about noisy differentials an the XJ40, thought I would add my recent experience to the mix.
My 1991 Daimler diff was very noisy when I purchased it a year ago, also had sloppy rear suspension, primarily due to failure of the self levelling system. This was factored into the purchase price and I finally got on to it 9 months later.
I dropped the whole rear suspension assembly out. It was relatively straight forward even on my own, although would recommend using a good heavy duty trolley jack. Having a good air impact wrench is bonus too. An excellent description of how to do it can be found in the Jaguar Monthly XJ40 Engineering book, published by Kelsey Publishing. It is out of print but there appear to plenty of copies available online.

The diff was removed from the assembly and taken into a diff repair specialist. I sourced and provided all the bearings, seals etc and they dismantled and reassembled it, a total of 5 hours labour. They were also able to tell me that the crown and pinion is in excellent condition with hardly any wear, which is reassuring. I also took the opportunity to remove the self leveling shocks and associated plumbing and replace with a standard shock absorber kit, any rubber bushes that looked suspect - including the drive shaft coupler, and replaced the front shocks - the top bushes had totally collapsed.

Refitting the suspension assembly to the car was a little more difficult, needing two people to guide it into place, however it all came together ok. End result is fantastic, totally quiet, with transformed handling and ride. I've just come back from a 1400 km road trip, didn't want to stop driving! I imagine it might be close to what the car was like when new, really worth the time and effort.

 

I must applaud your efforts. It's really good to see when someone values the car enough to invest in it to that level. Did you get any pics as you went? I'd be curious to see them if you did.

 

 

Thanks.
As I said, well worth it, In my experience the car is as good as anything on the road as far as comfort and handling go, for a lot less money even with the cost of the work.
Sorry no pics this time, but I'll look to do better in the future.

Chris

 

What parts did you replace in the diff? A kit or separate bearings, etc? Who did you use? Might be useful for someone else here

Was your SLS suspension completely knackered? They seem to be very rare in UK but back on mainland plenty of people still use SLS with no problems at all.

 

I replaced all bearings and seals - I purchased items separately, but output bearing kits are available.
I'm in New Zealand, so for kiwi jag enthusiasts, Geartech in Palmerston North did are good job and are easy to deal with.

I'm not sure if the SLS hydraulic system itself had failed, but both the shock absorbers certainly were stuffed. They are not easy to get and expensive, so a standard shock conversion kit was a good option and the result is excellent.