I am starting to reassemble the differential after cleaning up all the broken bits and getting new parts. Today I am putting together the Powr Lok unit and I noticed an oddity in the clutch plates.

In the XJS manual for assembling the clutch pack it shows 2 clutch disks together, which makes no sense to me because they will move together. The order shown is Bellville washer, clutch plate, clutch disk, clutch disk, clutch plate.

Wondering if the diagram was correct, I looked up my E Type manual and it shows Bellville washer, clutch disk, clutch plate, clutch disk, clutch plate.

Digging further I looked up the Daimler DS420 manuals, as it uses the same differential. The 1969 and 1977 versions show the E type order, the 1985 and 1990 manuals show the XJS order. I also have a Series III XJ12 manual and it showed the XJS order. Series II XJ12 shows the E Type order.

Why the change in the 80's and does it matter? I assembled it the E Type order, but now I'm doubting myself. Thoughts welcome!

The XJS order should have considerably less locking ability than the earlier versions, as there is only 3 surfaces that move relative to each other, while the E Type version has 5.

E Type: Notice the order of the plates numbered 3 and 4, and how they alternate.


XJS: Notice how the order is 4,3,3,4

 

Do you mean the DS420 uses the same housing or just
the limited slip unit?

Plate type limited slips are often assembled with the
friction plates in different arrangements according to
the desired characteristics. Calgary has a number of
good 4x4 aftermarket shops that might be willing
to give you some pointers.

Or start digging around on 4x4 forums on the topic.

 

Xj6 manual pics

 

That's an XJ40 manual I assume? Interesting that it has 7 plates ( instead of 5) and still has 5 surfaces that have differential motion.

 

Same housing and limited slip. It's the same IRS as the XJ series.

Sounds like there was some issues with clutch noise when cornering, so in the 80's Jaguar revised the order of the plates to reduce the locking effect.

 

jagboy64, jag changed the effort for locking to quickly , because for some inexperianced drivers in incliment weather the car could more easily get out of control, like lockup and spinout!

my 1978 XJS had the low BIAS Lsd, when i disassembled it and rearrainged the plates, mine did not have the Bellville plate, but i had some old Corvette LSD, late 50s, i think 1959 corvette, YUP they fit in perfect, still in no probs.

called the high BIAS LSD

but with my torque empheses gear ratio it will spin out quite easily, gotta just drive thru it!

ever wonder where Jag got there LSD parts and differential stuff?? maybe Dana, things change but copying/redevelopment GKN.

a quick check on bias ratio, is making slight chatter noise from diff, going around slow corners, but very important to use a GOOD LSD gear lube, GM developed one in the late 50s for there lsd diffs.
still available today.

 

Ron,

I have a set of clutch plates from Dana, they are identical to the original Jaguar parts. With the cross shafts broken, I think there was basically no differential action, so it was very easy to break the rear end out. I certainly want to avoid that again.

It's a convertible, so always driven in nice weather and only very occasionally caught in the rain. It would probably be just fine with an open diff.

The same Powr Lok was used in Chrysler C bodies from 1958-69, although they used 2 Bellville plates, and Jaguar uses one. Ford also used it in the front axles of 4x4 trucks in the 70's

 

Some of the domestic makes used plates with friction material on them, similar to the clutches in automatic transmissions. Jaguar didn't, just steel on steel.

Ford also makes an LSD additive, in addition to GM. One is better for plates with friction material and one is better for plain steel plates, I just can't remember which is which. I have to look it up.

 

To provide closure to this for future searches, it appears that Jaguar changed the order of the clutches and disks about 1985 to provide less locking. I originally assembled it the early way, with clutches and plates alternating. The best I could apply with my torque wrench was 120 ft-lbs the axles didn't move.

Then I took it part and reassembled the later way and the breakaway torque was 65 ft-lbs. Spec in the manual is 40-70 ft-lbs.

I didn't want too much locking, as I didn't want it to be too tail happy in the wet. So there are options, depending upon how much locking effect you want.

 

right , jagboi64, it really depends on your driving style, (women probably like a light or no locking)where as the stop light pickup guys would prefer a solid lock!

hey what does 64 mean in your name??

 

When I first joined one of the Jaguar forums I had a 1964 E Type, thus the number.

 

Do you still have it? We're mates, mine is a 3.8 with the 3.31 LSD
Very interesting findings wrt the assembly of the plates, thx for sharing.

If I understand correctly you finally decided to remount the plates with the XJS 4334 "more locking" order, without having a try with the 4343 "more locking" order of the E-Type.
Was it also a choice guided by your fear of breaking a shaft when not enough slipping as you mention in the case of your Dana differential (not clear to me if this Dana was a LSD diff or not)?
And do you think that a 4343 mounting order of the plates would also benefit an E-Type to more counter happy tail in the wet?

 

Yes, I went with the less locking order of 4334. The car was very twitchy in the wet before, and I want to eliminate that. I don't really need an LSD at all, I'm not doing acceleration runs in it. I could have kept the E Type order of 4343, but I didn't want to do this again if I didn't like it, so I kept the factory order.

The Jaguar differential is based on the Dana 44, but there are some differences. A lot of Dana parts fit directly, such as the clutch plates. Much cheaper too, for example a set of clutch plates from Jaguar in the UK was £420, I bought it from the USA for $69 USD.

If your E Type is tail happy in the wet, then certainly going to the "less locking" arrangement of 4334 will help.

I sold my E Type about 10 years ago. I enjoyed it, but selling it paid off my mortgage!

 

When I got mine it had been replaced with a 2.88 from an XJ. I liked the ratio, gave better fuel economy and less heat on the highway. The car has plenty of torque, so I had plenty of performance.

 

something to be said about USA prices!

back 1994 ,i wanted to change my factory rear gear ratio, so a called someone(cant rmember who) in England, explained what i prefered ratio,3.73, just ring and pinion/crown, quote was $1150.usd, plus shipping!

i went a local Daytona off road shop, showed the counter guy my old gears, said,"OH those are JEEP" he went in back room , came out with a new set of 3.73 , i bought for $175.usd.

they fit my Dana 44 Jaguar diff. perfectly, still in it and no problems!

and with my overdrive 700R4 trans. final ratio is 2.60-1 for hyway cruising.

 

You want to say what the Crownwheel and pinion is also the same (Dana and GKN)?

I like it too 2.60-1. I have GKN 2.88 for rebuilt. Dana is offer 2.60.
My modified 4L80E has 2.95 first

 

Generally, no. Jaguar used 7/16" bolts and Dana used 3/8". It is possible to use a Dana crownwheel on a Jaguar carrier with collars on the bolts. Typically the splines on the Dana pinion are also different to Jaguar, so a different flange would have to be used.

 

.

now yo making me think about the bolts 22yrs ago,WHEW, it seems the guy at drive shop was aware of bolt sizes, and supplied me with them, like a shoulderd bolt, hardened steel!

must be OK, rear drive is working fine no problems,or noises!

and for the spline flange is use a standard GM U-joint part, along with Aluminum single piece driveshaft, again all is fine!

did anyone ever count how many GM parts are in an XJS, even window motors,etc.

 

Too many. I think I had every single one of them fail on my 1992 Series III V12 car. Didn't have anything Lucas fail on me!

 

Ron, you mention a shop in Florida that works on Jaguar diff's, My 91 has a 3.54 with the speedo wheel sensor. Old GTJ in Ohio set it years ago. First setup it whined, to say the least. Second setup is to much slop for my liking. The shops that I asked don't work on Jaguar diff's, don't know why. All I want is a tight 3.54 that don't clunk or whine.