HI I am looking for information on gearing up grades for my xjs I have read that you use xj6 differential to do that. what I am trying to find out is can I use the ring and pinion gear from an xj6 and put them into my xjs and rebuild my differential useing the new ring and pinion that way I can save money by not buying a complete differential and go to the 354 gears out of an xj6.I am also looking for who might sell a kit that would allow me to run two throttle bodies?
Thanks spencer

Submitted by silver007@shaw.ca on Sun, 03/20/2011 - 02:46

I had an aftermarket set put in the diff of my 83, replacing my 2.88, a friend of mine purchased my used set and put it into his E Type, much better for the highway use , and worked okay for the slalom also. The S really needs a 3.54 to get it going in a hurry.......as mine has now done for many a season. do not forget to put in the limited slip additive with the fresh oil......

Submitted by dougdwyer1@com… on Sat, 03/19/2011 - 21:53

As far as I know none the internal differential parts are interchangable between the inboard and outboard brake cars.

(Some have swapped *entire* outbaord brake rear suspensions, differential and all, into an inboard brake car. It isn't all that complicated, it seems and, as mentioned, the 3.54 differential is common on the outboard brake cars )

Anyhow, you'll need gears from and inboard brake car such as the Ser I-II-III XJ6 as you mentioned or another XJS. Problem is the 3.54 gearset is rather rare. From about '82 onward a 2.88 ratio was standard. Prior to that 3.07 and 3.31 were used. Prior to that the 3.54 gears used on XJ6s in the early 70s and other Jags prior to that. Additionally, I think there were some differential changes in the md-70s that might preclude using an earlier gearset---can't swear to that, though.

Another alternative is aftermarket gears. Your differential is similar to the Dana 44 differential used in various US trucks and Corvettes. In fact, for a period in the mid-80s Dana corporation was actually producing differentials for Jaguar. The Dana-made diffs are easily recognizable by the lack of a drain plug in the bottom. Anyhow, some guys have been able to make aftermarket gears work.

I would contact Coventry West (800 331 2193) as they really know about Jag diffs. In fact, JCNA Pres Daick Maury heads up their rebuild department.

Cheers
DD

Submitted by sbsteed@aol.com on Sat, 03/19/2011 - 21:29

Hi steve from what I have read the only gears that I can use are from xj6 type I, II, II but I realy dont know that is the only information I have, if you can tell me that yours will work in my 1988 xjs I would be interested
thanks spencer

Submitted by silver007@shaw.ca on Fri, 03/18/2011 - 00:23

our friend at Vintage Jaguar works sells them c/w a new throttle pot to enhance performance.. call Walter , he is a straight guy and does good work ready to go. Art

Submitted by dougdwyer1@com… on Thu, 03/17/2011 - 20:32

What year XJS? Inboard brake differential or outboard brake differential?

AJ6 Engineering sells a quad throttle body set up, I think.

Cheers