Limited slip differential REVISITED
 

So while waiting for my timing parts to arrive I found some money to be burning a hole in my pocket, and some time waiting to be killed and i began moving onto project two, the LSD.

Which of course led me to the search function of our fine forum, yielding these results.

https://www.jaguarforums.com/forum/s...ighlight=lsd--

https://www.jaguarforums.com/forum/s...ighlight=lsd--

https://www.jaguarforums.com/forum/s...ighlight=lsd--

https://www.jaguarforums.com/forum/s...t=lsd--&page=2

https://www.jaguarforums.com/forum/s...p+differential

https://www.jaguarforums.com/forum/s...ighlight=lsd--

https://www.jaguarforums.com/forum/s...ighlight=lsd--

Here's what I found.

A bunch of conjecture, and really expensive aftermarket options.


Questions to answer:

SO have we yet established that the rear end is in fact ford?

If so, what parts can we swap?

Is it the 8.8 or 8.0?

What's the cheapest route to an LSD?

what's the easiest route to an LSD?

Has anyone actually done this with ford parts yet?

Before this thread dies and becomes one of the numerous dead threads above, can we at least put all the info together into one spot so the next time someone searches they get a nice easy answer?

No! That is not the way things work.

:icon_doh:I set myself up for that one didn't I. :icon_slap2:

I have rebuilt my diff and wanted to go to a lsd. As much as I could find out was it is a salsbury and it does have dana stamped on the ring gear oddly enough. When I went to order the parts from Jag the xk8 and xkr had the same parts and gear ratio. It does not look like any ford diff I have seen, on the outside at least. I bought my 2002xkr used with 50k on it and the diff started making noise with in 2k from purchase. It seams that the ring gear will warp if you are hard on it. Something I have never seen before. This is the weak spot on our cars. I am still looking for a viable option for a limited slip, but the soft gears should be addressed as well.

When I bought my car with 15k mi, it had a noisy differential. It was replaced under the original new car warranty. Apparently, this differential is not up to the task :icon_no:, especially on the XKR.

There are a couple of options for LSD on our cars, none of which are cheap. I will try to do this least expensive to most. The first would be to stay with the ratio you have & install a 6 cyl XJR diff this involves also replacing the front mounting plate for the diff & making sure you get the correct flange. The second would be to purchase the Quaife unit from one of the three sources in the UK, ( Paramount Performance, Racing Green Cars or TL Jaguar). This involves buying the unit then having it installed in your diff & also has no warranty in the US. The third which can only be done on cars with the Mercedes trans invloves fitting the 6cyl XJR diff & using whatever ratio you prefer, however it also requires you to reprogram your TCM at a cost of close to $2000.00. I have done this to my car with a 3.58 ratio along with many other engine upgrades, the difference is amazing. I would recomend this to anyone looking for LSD & an increase in performance. My next project may very well be to go to a 4.09 LSD which should make the acceleration neck snapping.

So you are suggesting that I can go find an year xj6, pop off the diff, and fab up a mounting plate. So it's almost a drop in replacement for the xk8 diff except it's limited slip with the same gearing and everything? What kind of power can that old diff take?

What year and model Jags have the Benz trans?

Who is reprogramming the TCM, aftermarket or dealer?

As far as the labor, I do all my own work so that's a non issue. I just hate going in blind.

What you need is an XJR 6 diff & front mounting plate & it is a straight drop in. You will need to modify the exhaust mounts for the overaxle pipes. The Mercedes trans is fitted to supercharged cars from 1998-2002. If your car is not supercharged you don't need to program the TCM. You can fit 3.07 3.27 3.58 3.77 or 4.09 ratios.

Mine is 1998 Xk8 (no supercharger for me :( )

So I'm going to go dig up an xjr 6 rear and some 3.77's whoo hoo!

Any Ideas where I might be able to find such a part... I just ran a quick search and it seems to be a hard part to find...

Here is a link to Coventry West http://www.coventrywest.com/ ask for Pete Bond xt 120. He is well aware of what I have done, they can supply the diff as well as a used mounting plate. Just make sure you tell him which flange you need on ther diff. You may want to go 4.09 as you car revs to 6500 rpm & that should put you pretty close to 150 mph & the speed limiter is @ 155. Good luck on your new car

I think I tried that LSD, but that was back in the 60's!! :icon_pala:

There has to be a way to get some LSD and better gear ratio's in these cars.....

I think the Ford theory is for the S-type since so many parts are interchangeable with Lincoln LS. The diff does look much like a Ford 8.8. The Lincoln LS guys have swap there diff for Ford LSD, which makes is believe it can be done. I had some guy look at mine and said the only thing that he saw was the cover plate might have be changed and it might not fit with all the stuff under there.

Hmmm I might have to find a 03 Cobra rear dif and see......3:55 gears would be NICE........

What would be needed to change the speedo gear?

What spline are the axles?

dont know Ill i know is ther was a company KBX Perfromance that swapped lsd from a mustang into a 2000 Lincoln LS.

What is the stock diff. gear ratio? ('05)

You don't say what Jaguar you have. I believe Dana diffs were fitted on the XJs up to the XJ8 of 1998. S-Types will probably be some Ford part, and the X-types used Jatco, I think.

What is the stock differential gear ratio is on an 05 XKR (or any XK) is?

This is all i have found on gear ratios for S-type R

Gear Type 6 Speed ZF Automatic
Final Drive Not Available
1st Gear Ratio 4.17:1
2nd Gear Ratio 2.34:1
3rd Gear Ratio 1.52:1
4th Gear Ratio 1.14:1
5th Gear Ratio 0.87:1
6th Gear Ratio 0.69:1