Hello,

I just purchased a 2007 XJR and although I'm very happy with it I have noticed that it does spin one or other wheel a lot. I think it would be a lot better with a Limited Slip Differential.

Has anyone replaced their differential with an LSD on a XJR? Did it make a big difference? Were there any problems associated with the switch?

Also, what brand LSD to use? I am familiar with the Quaife but what other choices are there?

Thanks in advance.

Steve

 

I've been searching the forums and it seems that a few people have upgraded the diff on XK's but that it is not common on XJ's. I emailed Quaife and was redirected to Racing Green who can supply a Quaife LSD, it would cost about $1500 shipped.

I'm wondering why there aren't many XJR owners who have done the switch? Maybe feel not worth it or doesn't need it? I guess I might be a bit fussy having come from an AWD background where wheels don't spin unless using launch control. I'm probably a bit lead-footed too!

I'll find out what fitment will cost locally.

 

Hi Pumpkinate
I had the Quaife LSD fitted to my 2003 x350 xjr by racing green
My first impression was what a waste of money , but that said i run the car at Santa pod on their RWYB days (1/4 mile drag strip in the UK )As i first posted this on another site it was picked up by Cambo 351, and he had a look at my times and found that my 0-60ft times had bettered them self s by 10%,so although i haven't noticed much improvement my car has ?
As my car is not my daily drive i don't have a favourite bend or turn to use as a yard stick
Would i have this done again? mmmmmmmmm time will tell
Hope this helps (or adds to your dilemma LOL)

 

It’s not just at full power that it can be beneficial; in your climate in slightly slippery conditions it will also prove its benefits. Of course the more power you have the better a LSD becomes, but just as well for me in winter conditions.

 

The fact is it should not be spinning if the electronics are doing their job. I think you have something wrong in the traction control system.

Modern cars like the XJR use the rear brakes as the slip limiter via the traction control software. OK, the rear brakes wear out quicker but that's the way the car industry is going because LSDs cost more than putting in the electronics. Of course you can fit one yourself if you can find a suitable supplier, no problem.

 

This is correct, when one wheel spins, the traction control clamps the caliper down on that wheel, causing the power to transfer to the other side though the spider gears. If yours is not doing it, you have a malfunction. If the second wheel loses traction too, the computer will then reduce teh throttle opening. If the computer detects any lateral movement with this, it can further reduce power and fiddle with the brakes to prevent a spin.

 

Davey your post brought back memories of Santa Pod! I live in the US now but spent many a dirty weekend at the pod in the 80's and 90's you know what I mean about Dirty! Do they still do the night meet in November! I remember my wife before she was on my mates shoulders spraying Bud over lots of naked people in the main tent one Saturday nigh! Oops too much information as to the LSD I think at the strip you def need it as long as the nanny traction con can be completely switch off.

 

Cheers guys,

The traction control is definitely working, but I am an enthusiastic driver (= foot to the floor). I'm aware of momentary wheel spin then the wheel is braked, and I can feel the throttle being dulled which is annoying. It kind of feels like the car is fighting you rather than working with you. Of course, when I turn the traction control off the car smokes it's tyres around round abouts and even accelerating up a straight road. An LSD would surely help. As I plan to up the power later I'll likely go for the LSD (either now or when I do the other mods).

 

What happens when you actually want to drive? AND use the power the car came with? Frankly I find the traction control system on an R so intrusive I refuse to drive with it on.

The car is SEVERELY traction limited, to the point of making the power unuseable at low around town speeds.. And the traction control might as well be tantamount to some bozo randomly pulling the emergency brake at the least inopportune times, with NO warning. Aka, when I'm trying to pull out hard into traffic, or make a turn at an intersection. I'd much rather have the car break a tire loose (and even blow sideways a bit.. gasp). Rather than sit there about to get creamed because the car decided to take my foot off the gas for me.

The point of the LSD is to allow me to put more of that power to the ground at any given point in time. WITHOUT it spinning. These cars break a tire loose (with the traction control off) if you look at them funny. Especially in the cold or rain.

All of these traction systems are good for are two things.

1) Allowing inept drivers to semi-safely control 400hp cars. Aka the guy that would bug out when the rear got a bit loose, or his wife.

2) Lowering insurance rates because they can give joe shmoe a 400hp car and he has a reasonable chance of not wrecking it.

You know the "muscle" cars of yesteryear had less power than most modern powerful cars.... But everyone looked at them as death traps, because the gas pedal was connected to the throtle body (or carburetor) by a mechanical cable. No algortyhm in the middle to decide if your chosen level of trottle was prudent or not.

Today's heavy cars advertise 400, 500 hp, but they decide how much of it to let you use at any given point in time... Where's the fun in that?

Take care,

George

 

Thanks George, you have expressed my thoughts exactly. You are right, the traction control has been getting annoying and I have been turning it off too.

 

Hi, how did this end. Did you install the Quaife from Racing Green?
I have the same problem, and also half a year with winter. Anoying traction control works against me..

But if i turn off the traction control or esp or whatever it is called, I will loose both the wheel spin control and dynamic brake control witch corrects for over and understeer right? Does it also turn off any other things?

Ole Mobeck
Norway

 

I have to admit, I clicked on the thread because I was simply intrigued by the thread title. It took me back to the 60's. Alas, truly car related thread however.

Please don't ban me:-)

 

Wow, old thread.

Just to put in my I did get a Quaife LSD installed in my XJR, and frankly it's transformed the vehicle.

I got it from TL Jaguar in the UK, but Racing Green is also an official agent for this particular model differential.

Did a little snow driving while the car was still in Switzerland, it was much better.

The traction control is less intrusive than with the open diff, it seems to cut engine power less, and use the brakes a little more.

Both Davey and myself drove our Quaife-equipped XJR's around the Nürburgring, in some cold and slippery conditions, I personally don't think we could have driven as hard as we did in those conditions without the LSD.


I also found a big difference at the drag strip, when we were at Santa Pod last year, there were four X350 XJR's there, two with open diffs, two with Quaifes (Davey & myself) the Quaife cars were the quickest off the line, by a considerable margin.



At this point in time, Quaife is the only option for an LSD to suit our X350's.

It's not a cheap exercise, but worth every cent...

 

Hi Ole,

Yes! I did get a Quaife LSD although I can't remember who I got it from. It transformed the car and is well worth it IMO.

Cheers,

Steve

 

I Just posted on the STR section about fitting a LSD to my XJ8

I cant justify using a Quaife for the XJ8 if it was an XJR I would consider it

I am going to go the phantom grip route

I just need to get the measurements for the diff they don't know if an off the shelf unit will fit or it has to be a custom made unit

If any member's have the measurements or an old diff lying around I would be quite happy to pay for the shipping to and fro from phantom grip to get one made that way any other member's wanting to use one of these type LSD conversions can just buy it instead of going through the measuring up stage like I am

 

Unfortunately I left the old diff centre behind in Switzerland, it's probably still there in my mates garage, unless he's chucked it in the meantime...

 

Am not 100% sure, but I thought that the XK aluminium bodied diff is the same as the ones used in the 04 XJR you have.


If so, then here you can find more details about the diff itself from quaife with all measurements:
QDF3W - Quaife Engineering

 

Hi and thanks for advices, I wil certainly now mount the ATB Quafe diff as I am reminded everytime I am out to have some fun With the XJR. I include a picture of my diff and I have confirmed that Racing Green can supply the diff to fit this unit.


And here are a video of my last xjr, a 1996 Manual. With original lsd

 

I'm rather disappointed that LSDs didn't come standard in XJRs and SuperV8s in the first place, this is way too expensive of a car to have a one-legger. Especially the XJR. Oh you want the sports version? Still one wheel drive!

 

There's a story to this, i'll tell it again...