I am on another upgrade mission to change the single trac rear to posi trac and I seen a few folks on here who say that is on there to do list and now I am in the research phase for the changeover. I sent out a email to a company called Quaife for more info on there gears for the rear. Any of you fellas with more knowledge than me would be greatly welcomed. The rear differential looks easily to get to and out from what I seen under the car.

 

This was one of the first mods I did to my 2002 XKR. I knew I would be upgrading the s/c and I wanted the power to go into acceleration and not leaving 20k miles of tire rubber on the road. I selected a Quaife Automatic Torque Biasing (ATB) Limited Slip Differential. It uses gears rather than clutches and is designed never to lock up. There are some who don't like the Quaife because without locking up there is no "drifting" through corners. However, I don't want to "drift" through corners. The XK8/R is a GT not a racer.


I bought Quaife from a company called Pro Street (Part Number QDF5W). They had the best price and I've been very happy with this LSD. Before you decide however, you should check with forum member avos. He is very knowledgeable on the different LSDs available for our cars and is a fan of the clutch type LSD.


Mark

 

Posi-trac is a limited slip unit that is a GM trademark name.
It is a common phrase but it is like calling a vacuum cleaner a HOOVER.
Not all vacuums are Hoovers and not all limited slips are Posi-trac.

Jaguar used Thornton Power Locks but people called them Posi-tracs.

The last Jaguar factory LSD units were installed in 1997 (they are clutch-type).

I like Mark's Quaife LSD as it bolts in without any modification to existing components.

I don't know much about aftermarket clutch-type units for the later (1998>) cars.

bob gauff

 

I've got the O.S. Giken limited slip diffy. I love it. The ability to hit the gas hard when turning right (US) and pulling out into traffic is incredible. The ability to leave a light under WOT and go perfectly straight while laying 2 tracks of rubber is, well, incredible. Go for it! No more fish tailing for me. =)