I have a 2006 XKR Victory Edition. I'm currently in the process of trying to find out the cheapest and easiest way to add PosiTrac/LSD and change the gear ratio. I was under the impression the differential was a DANA 44. Is this true?

The questions I have are these:

-What are the differences in the rear ends between 98-06
-If I change to a 4.09 gear how do I re-calibrate the speedometer
-How many hours of labor are required to do a rear-end swap

Hope someone can help.

 

No. It is related, but not a DANA44 and those parts won't fit. There are a couple of options for a LSD, but none particularly cheap. Quaife is probably the best known and most readily available.

Around $1500 for the unit and any here from $500 to $1500 to rebuild the diff depending on how far you go (new bearings, shot peening, etc)

I got a Quaife from Tom Lenthal in the UK. Don't bother with the US re-sellers, they can't get them, but Tom has some in stock.

None

You will need to reprogram the transmission controller, which at present time, no one knows how to do for the 6spd, at any price. There are a few threads about options being explored, but nothing confirmed working.

Not sure about hours, but the rear sub frame comes out. I recently paid about $1700 to drop the subframe, do shocks, springs, new bushes all around and install the rebuilt LSD pumpkin I had ready. In short, it's a lot of work.

 

Thanks I'm going to do the same. Buy a used rear end, have it built. Then installed at a later date. I was hoping to find a cheaper option than the Quaife.

Do you know where to find the gear 4.09? I'm not sure what to look for, considering I don't know what kind of rear end it is.

 

Without doing something really drastic and inventing your own, I think your options are limited to the earlier Jag differentials. Either as a gear swap from an earlier model or swapping the diff for one from an XJ6 that has a clutch type LSD as original.

I am honestly not an expert on this one but there are a few members who have done it and a few threads about it.

 

Don't forget if you don't recode the transmission controller you'll likely drop into limp home mode which is why more of us haven't done this in the newer cars. You can do an LSD you just can't change the ratio without throwing a transmission code and dropping into limp home. There are several of us watching to see if someone sorts this. Not much point doing an LSD without changing the ratio.

 

I would respectfully disagree on that point. In my case, what used to be a one tire fire, is now just hook and go.

Before the LSD I couldn't give the car full throttle in 1st gear, it would just break loose and spin. Now I can give it the beans, as they say.

Admittedly, this is with somewhat more than stock power, but even so, the problem was the same before.

 

I may be completely wrong but I think the 2007-9 XK has a 3.36 rear axle ratio vs the 1997-2006 ratio of 3.06. Both vehicles use the same transmission from 2003-2006 so if one could use the 3.36 rear end the perhaps the vehicle speed sensor from the 2007-9 trains would work?
Just thinking...
White Bear

 

This was my concern when first considering a gear swap. I’ve since spoken to another forum member whom says that he can do the reprogramming remotely, stating the following:

“Yep, it is possible…I can program any gear ratio to your car. After you have a new rear diff we can program it to your car. Gear ratios are not programmed in TCM, they are programmed in a VID block. I can modify it. No TCM flashing is needed. To modify it I need a laptop, with IDS or SDD installed, a cable (Mongoose or VCM) connected to laptop & vehicle.”

Again, this is not confirmed...but come winter time, I may test this theory.

 

And it IS possible to reprogram the TCM. JgaXKR had this done several times...at a cost of $2k. Post #18 is where he states the cost.

https://www.jaguarforums.com/forum/x...65/#post426774

 

That was the 5spd Mercedes transmission.

 

You're right. I knew he had a 4.2...didn't realize it was a '00. Thanks for the correction.