Anyone know if a 3.27 gear LSD from a 2000 XK8 (Part JLM20621E) is plug and play to a 2002 XKR?

 

The diff itself is, however the ratio change will be an issue with the transmission and ABS and the TCU from the XK8 is not suitable for the XKR.

 

Any mods for this? I'm assuming that any different ratio aftermarket would have the same issue.

 

Don’t think you right that it’s a LSD.

 

The easiest by far is to get a replacement used 14HU 3.06 differential from an X100 or X308 and swap in for the broken one. All X100 and X308 rears were open diffs, there were no limited slip diffs, to my knowledge.

If you want a limited slip diff, but don’t want to deal with the electronics necessary with a ratio change: - the easy but expensive option is to use a Quaife unit for 14HU.
- the complicated but probably cheaper (assuming you do it yourself, including harvesting the parts from a breaker) is to put a Dana44 locking 19 spline carrier (Auburn, Speedmaster, Eaton, etc.) into a 15HU casing, use a 3.06 ratio Dana44 ring and pinion, and adapt the prop shaft flange ( ‘02 XKR does have a flange and not a Jurid coupling, which makes things easier). 15HU is also stronger, so there is less chance of another failure.

If you want a ratio change and limited slip diff:
- by far the simplest is to swap in a good X300 XJR (1995-1997) 15HU locking differential with the 3.27 ratio.
https://www.jaguarforums.com/forum/x...change-251133/
- or do the above Dana44 ring and pinion with an aftermarket locking carrier for a ratio of your preference (could also use 15HU 3.58 gears from a non-locking X300 diff instead of Dana44 R&P)

For the ratio change, you either need to reprogram the EGS51 Siemens transmission control module (TCM) for the Mercedes 722.6 transmission, or intercept the canbus ABS wheel speed info and tweak it before forwarding it to the TCM. So electronics expertise is needed.
- An implementation of the latter is described here
- On minimal research (someone more knowledgeable please correct me), the EGS51 reprogram is focused on modifying the contents of the 93c56 eeprom. I would guess (but have not researched it) that a Mercedes programming tool is available to do that once you have created a new flash file. There seems to be someone who is willing to recompute the checksum for a revised ratio here. If it were me, I would probably just unsolder the chip, reprogram it with an Arduino or similar, and remount it rather than grappling with the learning curve of the Mercedes ecosystem, but I expect the knowledge around the Mercedes tools is out there somewhere.



It seems at least at sometime in the past there was an EGS51 reprogramming service available, but it allegedly cost $2000++

 

I did the Mexico 3:27 diff exchange in a forum member's 4.0 XKR and installed the Quaife unit about 10 years ago.
The customer sent the TCM to a 'tuner' to adjust the ratio change.

I also installed a 7" crank pulley and the car had impressive acceleration!!!!!! (wow)

He was back a few months later because he broke some teeth off the ring/pinion so he found a 3.2 liter X308 diff from Europe and I cut the pinion driveshaft extension for the Jurid coupler and installed the old XK pinion flange from the broken diff and swapped over the Quaife unit.

Back on the road.

 

Good info and lots to consider. I think a good next step will be to find a local indie drive line expert with Mercedes TCM experience. Opens my options.

 

As l remember it, although the EGS51 TCU could be programmed, most of the reprogramming was centred in Eastern Europe and involved the EGS52 TCU, this was much easier to program and was compatible with a wide variety of the 722.6 transmission applications. This was however found to be not compatible with the CAN setup in the jaguar

 

None of the X100 came with LSD. Swapping in a Quaife did not require any changes to the computer.

 

The RATIO CHANGE did.

 

Was clarifying the LSD portion of the "3.27 LSD from an XK8".