Here is a interesting question, for the longest time i thought my xjr6 had lsd in it. Last weekend i had to lift the whole car up to adjust my handbrake and what a shocker! i spun my wheel and the other side moves in different direction ! indicating it is indeed an open diff. now heres my question, i know the newer xj8 utilizes traction control to mimic lsd but what about our xjr6?

Jacky

 

The X300 and XJ-S were the LAST Jaguars to have Limited Slip Diffs.

The LSD will have a BLACK X or cross through the colored sticker on the diff. No BLACK X or cross means NO LSD. You can add one if you want. They are available. Might be that someone in the past replaced it with a regular diff?

I replaced DOZENS of XJ40 and X300 diffs for 'whining' pinion bearings over the years.

bob

 

The XJR6 came standard with limited slip. Trac Control was standard as well....at least on the USA market cars.

You LSD unit might be worn out. Or perhaps replaced with an open diff.

The diff on my XJR6 gave out at just 70k miles

Cheers
DD


PS-It dawns on me that your test for limited slip is rather universal but might not be conclusive in all cases...as there are many different types of LSD with different operating characteristics. Seems to me that (at least some) Jaguars used a 'ramp type' LSD that functioned as an open diff until xxx-rotational speed was reached. Others will chime in; I'm having a memory fade at the moment!

Cheers
DD

 

Other way around. The Powr Lok (that's a trademark, thus the odd spelling) is locked all the time until it needs to unlock, such as when turning a corner. It's actually quite an ingenious piece of engineering.

Standard test applies, with both wheels off the ground if you turn one by hand, both should rotate in the same direction.

For the OP's car, it quite possible the diff has been replaced with a conventional diff.

 

Interesting info! thanks alot guys for your input. I went through all the paper work the previous owner had done on the car, the only thing related to the diff is the pinion seal. Also the car is a canadian car so i assume all NA had the same stuff. i will lift the car up again this week to look at the diff see if it has a x on the label? , and where would this label be at ? is there another way to test it?

Jacky

 

****, thats concerning i will double check again later this week and report back, now.. assuming its an lsd and its worn out, can the friction material be replaced?

 

On mine the label is on the LH side of the differential. If you take off the rear LH wheel and look at the side of the differential you should see an approx 1" square red-orange sticker with a thin black "X" across it from corner to corner. You really can't miss it if it's there.

.

 

The friction material is steel plates, there isn't a lining like brake pads. Typically if things break inside they tend to lock together, rather than freewheel (don't ask how I know).

The friction plates are different from the earlier Series III/XJS cars, and as far as I know not available separately. The earlier plates are a Dana part.

 

Quick Update:
Lifted the car up once more, double checked the diff, and surely it does have the x on the side indicating its an lsd.
I thought maybe i used the wrong fluid last time, (75w90) so this time i got the right fluid 75w140 with a bottle of lsd addictive.

After the fluid change i spun my tires and still it acts like an open diff. so,, i called up the local diff rebuilting shop asking them what could it be, they told me the power lock diff is very durable and usually the friction material does not wear out that often, and usually its the gearing that wears out first.

I proceed on asking him how would you test these, and he suggested that i put the tranny in neutral and spin one of tire fast (not slow rotation) so i grabbed the tire and gave it a hard spin, and boom! other tire started spinning same direction! so there it is. if your curious about your lsd i guess this is how u test it?

 

If you tried to test it in park before, then the driveshaft is fixed and you'll probably overcome the friction in the clutches and it will appear as an open diff ( which it is at that point).

Depending on how the clutches are arranged, the break free torque is typically around 60 ft-lbs. The older style diffs from the E type onwards to the XJS had 2 different arrangements of the clutch packs. Same components, but the order in which they were assembled changed circa 1985. The older way resulted in a break away torque of about 130 ft-lbs, the later one 60-70 ft-lbs.

Higher isn't necessary better, it can make the car more difficult to handle in wet or winter conditions.

The XJ40/X300 style diff uses a different arrangement and number of clutches, but the breakaway torque is still in the 60-70 ft-lb range.

 

Is a 75W-140 oil specified in the owners manual? Every Jag diff of that generation I have seen calls for 80W90. I believe only the X Type calls for 75W140, and that's in the transfer case.

The friction modifier is to prevent clutch chatter in turns, it actually makes the oil slipperier and reduces the breakaway torque so it behaves more like an open differential.

 

Australian release diff oil is EP 90 , I know it's a bit late but I know that somewhere in my XJS manual it clearly stated in bold letters ,DO NOT USE FRICTION MODIFIERS IN LSD , not sure wether or not that would apply to the XJR !. Maybe worth looking into.