There are a few W/W threads on the XJS, notably the firewall battery posts. Also mainly Imperial (SAE) on the bodywork and engine anciliaries, and quite a few metric threads in various places on the engine, depending upon the year! The brakes are mainly metric threads, amazingly some of the calliper bolts are metric fine threads.

 

It's a real mixed bag. Most the body/chassis stuff will be SAE and fine thread. The engine stuff is very mixed.

The "+" electric junction posts on the firewall are some oddball thread. Not sure if it's Whitworth, though.

Cheers
DD

 

Thanks guys for all the input on the thread. It helps with a "heads up" when I get in to all this. I have found and ordered an original set of 4 volumes of the original XJS (Vol 1 thru 4) manuals. It wasn't cheap but with what I have I feel confident in tackling whatever I have to do on my initial service. I now have all the parts here to replace all 4 wheel bearings in the car. I would have expected that they would have gone longer than the 92K miles on the car but with one rear set bad on one wheel I'll just replace them all. Second will be to replace the final drive axle seal on the passenger side, which leaks somewhat but of course I'll make sure the vent isn't plugged up as mentioned in one of the books you guys have put me on to. Fun stuff! ...........thanks to everyone on here so far. No I can REALLY get myself in trouble. .............