All,

I am in need of a good condition differential for a 1994 XJS 2+2 with the V12, if it makes a difference. I seem to believe I saw one not long ago on here somewhere, but of course, I didn't need one then!!!

Let me know if you have one or know of one.

Thanks!

 

I have very nice one off 87 V12, not sure if ratio is the same, but mine is 2.88.

 

eBay seems to have tons of options...

 

Thanks guys. I have looked at Ebay a little and will again.

Are all years interchangeable? Again, mine is a facelift model, 1994.

 

I am almost certain that V12 facelift models with the four speed automatic gearbox have a lower (numerically higher) rear axle ratio than the three speed auto cars. From memory the facelifts with the four speed box have 3.XX:1 rear axle ratios, compared with 2.88:1 for the pre facelift V12s that have the GM400 three speed box.

Greg

 

Facelift 6.0l are very rare, how many miles are on yours?

 

Right!

It was 3.54 or 3.58

Something like that.

The extra power of the 6.0 engine together with the deeper gearing pretty much took care of the lazy off-the-line acceleration that the 5.3 cars with 2.88 diffs were known for. :-)

Cheers
DD

 

That would be an "inboard" brake diff. A '94 will be an "outboard" brake car. The diffs wouldn't interchange.

I *think* an XJ40 diff would fit, though.

Cheers
DD

 

Diff center from XJ40, X300 etc will fit in the XJS housing, I have a complete XJR center and 3.58 gears in mine. Another option is Dana 44 parts these will also fit in the XJS housing, a vast choice of ratios available with this option, make sure they are 19 spline, with a Volvo pinion yoke you can even bolt it up to the original XJS tailshaft yoke.

 

A wealth of information - as usual! Thanks everyone. I did confirm the 3.54:1 ratio for my year. And, am considering an alternate ratio moving forward. While I'm sure 3.54:1 is more responsive than the original 2.88:1, I would appreciate "more" if you know what i mean. I realize MPG would suffer a little but I'm okay with the trade off - to a degree anyway.

Any thoughts on ratios?

To answer the mileage question, she now has 42K.

 

XJ40 / X300 use the same rear end configuration it is completely different diff housings and not interchangeable with XJS, The XJS OB brake diff is the same as the inboard, the difference is the hubs. You can convert an XJS to outboard using XJ40/300 hubs and driveshafts. The only thing that requires mods is the outer fulcrum shaft is smaller in the XJ40.

The XJ40/300 diff center will fit in the XJS housing, as I have an X300 XJR center in my diff.

 

Almost all of the older Jag gear sets are the same so you can use gear sets from any XJ40, X300, XJ6 MK11 etc. You may need to either change your hemisphere or use a spacer.

I know a guy here in Aus that has 4.27 gears 6.0L engines and acceleration off the mark is remarkable with semi slicks. BUT with street tyres he can not get traction.

Jaguar had
3.77, 4.09, 4.27

 

for my 1978 XJS Dana,had 3.07, i used a set of 3.73, from a Jeep diff.

went together without drama, set gear lash, been fine 16yrs!

only thing when driving hard, rear drifts out because Powerlok is locking tightly,like a spool.

i live with it ,but careful on wet roads, some times fun,but wife lets me know about it.hehe

 

All of the XJS XJ40/300 diffs are based on the Dana, mine has a late GKN Salisbury diff and the hemishphere is still Dana 44, except for the 7/16 bolts.

Whohoooo way to go Ron - I have the same problem with the wife, they do not seem to appreciate getting sideways.

 

Adding to this thread and hopeing for clarity. Pretty much all earlier Jags ran the same diff (specifically the IRS setups). Being specific, they were all Dana 44 based units. But as with anything Brittish, there was many variations. Being Ratios, Open/LSD, Housing variations, Stub axle, etc, etc.

I would like to clarify housing differences and carrier differences. My 88 XJs has a 2.88:1 ratio LSD. I want a 3.54:1 or 3.31:1 ratio. I have suspicions the carrier and casing are slightly diffent to say a 3.54:1 setup. Casing requires some grinding? and the carrier is different (not sure if its offsets or just bolt diameters)?

Could I fit 3.31 or 3.54 gears to my original 2.88 diff. What mods are required or is it a straight fit. As I can get a 3.31 open diff but I require this to be a LSD. So I need to fit the 3.31 gear directly to my originals or will there be other issues as expected.

 

Correct all Jag diffs XJ/XJS, X300, X350 use the same Dana 44 derived diff center. ALL centers are interchangeable. The diff housings are not. All XJS and S1 to S3 XJ are interchangeable, including inboard and outboard brakes.

Only the carrier is different you do not need to modify the diff housing. I have an XJ40/X300 3,58 center in my XJS. The 2.88 carrier can have the 3.54/3.33 gears installed using a custom machined spacer. The 2.88 crownwheel and pinion are MUCH larger than the 3.xx so the offset to the carrier mounting flange needs to about 1cm closer to the center line of the diff.

Yes if you use a spacer between the 2.88 carrier and the 3.xx crownwheel. Other option is to use Jeep Dana 44 19 spline LSD carrier with matching crownwheel and pinion. The only difference are the pinion input yoke spline and the crownwheel bolt size (Jag uses 7/16 and Dana is 3/8)

 

Subscribing...

 

Ill post so i can find later. Ill check the # on the new diff sitting in the garage. Has power lock i know and i beleive a 3.54. Think it was red and yellow stripped with black x

 

What is the differences between the facelift 6 and 12,??