Hi all, I don’t normally post over here, I hangout in the series 3 xj6 section, my car is lumped with a cammed and tuned gen2 lt1, anyways, I need something in the 3:54, 3:73 area.
on to my question and reason for asking it,,,, I have a line on an 86 v12 xjs rear end, and cannot seem to find any info that tells me for certain what ratio is, I have read it’s a 2:88, a 3:54, and even one reference saying 4:10 ( I think That one my be a bit suspect..lol ). I am getting rear end regardless ( whole cage and everything) and will rebuild it with 3:54 if I need to, but wondering who knows what expected ratio should be, I know it’s supposed to be a lsd ( mine already is so no big deal there)
reason i will buy it regardless is that I can get it rebuilt whilst not taking car off road, and for the price I am paying I cannot pass it up!!

so.... what’s the ratio? 2:88 as I am suspecting or possibly a 3:54 or something different???

 

Its a 1:2.88. Well, it should be if you've been told accurately what car its from. All HE V12s have a 2.88 diff. The I6s have a 3.54. With the facelift cars, particularly after the brakes moved outboard it changed again, or maybe when the transmission changed. Anyway, if yours is a '86 V12 its a 2.88. They're all LSDs.

 

86 will be 2.88. Only the facelifts got the 3:54. Might be easier to find a 3:31 from a 70's XJ6 sedan but it will be open diff. The 3:31 is a great ratio for a SBC with a stockish cam. I upgraded to a 3:73 but I have a 3:31 I converted to an Auburn locker but I'd want a mint for it and it would cost dearly to ship.

 

I am getting entire rear end for 200, so I ain’t mad! Lol

 

you can get an 19 spline Auburn locker for Dana 44 along with a Dana 44 ring and pinion and make it anything you want. The input shaft seal can be a bit fidley though. You can also switch to a conversional input adapter.

Like this one
https://www.summitracing.com/parts/aub-546085

 

Here's a deal hard to pass up. Just make sure it's a quiet design.

https://www.ebay.com/itm/32461820394...AAAOSwKZxgmuI~

 

Just be aware the between 85 and 87, Jaguar actually used 2 different diffs in the XJS, both 2.88 posi. The Salisbury type, based on the Dana 44, was like any other XJ6 70-87 unit (identified by a drain plug on the bottom). The other type was called Dana (or that's how I've heard it called) and is completely different than the Salisbury and has no shared parts that I am aware if. That unit has a totally flat bottom with no drain plug and a square input flange (the Salisbury input flange is round). You can also recognize it by having 3 bolt output assembly flanges (to the main case). It's a real albatross- none of the Dana 44 style parts will work on it, including pinion and output bearings, and most diff shops won't know what to do with it. As far as I know there are no other gear sets that will fit either..... I had those units on my first XJS (85) and my 87 XJSC had one too....

For the 88 XJS, Jaguar went back the the Salisbury style (now with a cast aluminum rear cover and a speedometer sensor) and used that basic style through the 1996 end of XJS production

Now you'll be able to tell which is which.... A super deal may or may not be one.....

Good luck
Andrew
Jaguar Specialties

 

And here I was thinking that it would be a bonus if I scored the Dana, sooo much misinformation on the web these days, I will see what it is before I undo the first bolt!!! Thanks everyone

 

Just for the record, Dana 44 parts will fit into a Jaguar DANA casing. I have recently fitted a Torsen-style LSD, an Eaton Truetrac unit for a DANA 44 into my own car. This thread will do something to demythologise the subject!
https://www.jaguarforums.com/forum/x...tified-229645/

I am NOT saying that a Salisbury (ie GKN) will not be a better bet for you, I am sure it will, but just that DANA 44 stuff will fit.

 

super deal , i paid 150 back 25yrs ago!
Jeep 3.73 ratio, in a 1978 XJS diff unit!

 

Good to know on the Dana diff. I'm not sure how many users get into it quite that far, especially since the later XJS 3.54 Salisbury style units are still out there, but good to know.... Not clear if a Salisbury/Dana 44 ring and pinion set will fit in the Dana unit or not, but again, it has never really come up before. If someone is going to go to all the trouble of changing diffs, you would think a more aggressive (like 3.31 or higher) R&P would be part of the plan too,. Posi is nice but 2.88 is lazy, especially if you have an overdrive trans.....

Thanks

Andrew
Jaguar Specialties

 

so true about miss info about DANA diff units,!
Dana made the 1st LSD as i know way back with GM 1958 Corvettes!
in my 1978 XJS LSD , i used some GM clutch plates , from a 1959 Corvette LSD plate diff unit!
, because they were Bellville style parts, more bite less slip!.
little tricky in wet weather , but you just drive thru the slide, and come out with power!

 

I wish I understood this stuff and what the heck y'all are talking about...

 

actually DANA made there 1 ST , diff(not LSD), back in 1943 war years, for trucks!
ron

 

correction 1st DANA 44 diff !

 

here you go, JJJ

https://en.wikipedia.org/wiki/Differ...hanical_device)

https://en.wikipedia.org/wiki/Limited-slip_differential

When it comes to LSDs, most use clutch plates to lock the axle each side, to prevent too much slip on one wheel as compared with the other. This is what Ronbros was mentioning. How much slip the diff allows before locking the axles is a matter of taste and judgement. The Eaton TrueTrac made Torsen-type LSD diff, that I fitted to my car when the DANA LSD failed - see the link to LSDs above for an explanation of that type - uses gears instead of clutches to achieve the same effect. Highly recommended.

 

yes greg is correct ,, the difference for me is the cost of a Torsen compared to a Dana type!
Torsen 25 yrs ago over a $1000. bucks , used good condition Dana LSD unit , $50 bucks(Corvette junk yard).

 

No such luck over here, Ron, but prices are more reasonable now. Brand new, in the USA, the DANA posi for the 44 cand the TrueTrac are about the same, 550 USD or thereabouts.

 

Bringing this thread back from the dead….. I have done the auburn carrier and Dana gears, however am now having ( like you said) Input seal ( pinion) issues, one I found listed for this fits the pinion nicely but not the actual diff housing, it’s too small, need a larger diameter and of course only one is long gone… current one is a national seal 5778, anyone got a another part number to try? Diff is actually at a shop and they called me saying it was wrong seal, and cannot find info on better one… any help greatly appreciated!
Darren

 

If you have the dimensions, you could comb through the National OIl seal catalog, they are arranged by size. Is it different from a standard Jaguar seal? If it takes a standard seal, the Land Rover AAu3381 is often cheaper than the Jaguar seal and is identical.