Hi All, Looking for general info on what to check prior to fitting a 2.88:1 Power Lock diff of unkown origin. Any checks I can do to establish its condition? I don't really want to strip and refurb if I don't have to? It looks like it's holding its oil so maybe just get it in and see what happens!

Any tips on the actual install? I'm swapping out a 4.55:1.

Cheers!

 

If the complete diff you can strip it and go all the way, may turn out to have been unnecessary or you can just rotate pinion by hand checking for smoothness and tiny amount of backlash and same thing on output shafts. If it feels OK fit it and then road test, that's the only real confirmation it's good. Toss a coin.

 

Agreed.

I would drain and refill with fresh oil. Easier for both plugs on the ground.

 

rich,

Has the diff been changed beforehand? Apart from the 2.88, I thought XJS either had 3.07 or 3.54 as standard?

Cheers

Paul

 

If the LSD is working, if indeed the diff is an LSD, then turning one side should also make the other side turn in the same direction (ie forward rotation one side gives forward rotation the other). A non-LSD diff will give the other side the opposite rotation.
It will do no harm to undo the rear cover and take a look inside to see if there is any obvious problem like broked gear teeth etc, and give the inside of the casing a good clean. As the others have said, if it turns smoothly, and the backlash is not too great and it seems dry, change the oil (Casrtrol LSD oil) and go with it.

Some tips on assembling it all into the cage - which is the most exacting part of the job - in this link; but my diff is a DANA, whereas I expect yours will be the more common GKN Salisbury.
https://www.jaguarforums.com/forum/x...tified-229645/

 

Paul,

HE down here was 2.88.
There was a change real late in cars production run, and I think?? that came with the 4L80E trans and the 6ltr.

The PreHE XJS were 3.07.

The S2 XJ12 with BW12 trans = 3.31.
S2 XJ12 TH400 = 3.07.

Other markets, I dont know which ones, but they were different on some spec cars.

 

Thanks for the link.

I'll certainly change the oil and have a look inside just to see if there are any obvious issues and that it's not full of water!

 

This guy does great diff rebuild videos:

 

what the hell did you do with a 4.55 ratio in an XJS!
it would need a double overdrive to be street useful?
and those gears would be custom ordered from a RACE shop!
also aMY opinion 2.88 loses a lot of acceleration,in low speeds?
wait a minute , what car is this in and what engine you gonna use?
ron

 

Ha! You're right it's not in an XJS. I posted here because I think the 2:88 was fitted in V12 XJS and I am sure there are plenty of knowledgable people on here when it comes to Jag parts. My diff is going in a Morris Minor!

Yes the 4:55 is hopless. Great for ripping up tyres no good for cruising at 70mph.

Oh and the motor is a 4.6L V8.

 

Nice car, ilike the side pipes, and kool wheels!
ron

 

If the oil is clean and the backlash not excessive you should be good. The diffs are quite strong, they don't usually have a lot of problems. Oil leaks perhaps, but that's usually about it.