Done for the day. Got the brake lines off. Loosened everything i need to take the cage off.

Got to go pick up some pipe tomorrow.

Moving along nicely. Need to order replacement parts soon.

I'm still up in the air about the diff and what to do. I think its leaking so I might take the cover off and new gaskets.

pic of how I left it and my system for keeping everything in order for rebuilding.

 

I'm 99% sure I have the 2.88 gear ratio from readings all the stuff out there. Is there a casting number or another way to confirm this.

And if I want to go up to a 3.** ratio is it a big thing to do. I plan on going to 4spd or 5spd down the road so I would rather do what I can now so I dont have to drop the rear end ever again lol.

 

Hi Rescue

The Copper Pipe and String idea works well

The Copper Pipe keeps the Bushes in line and the String keeps the Washers in order

 

Sometimes you'll find a small metal tag on the diff that shows the ratio. But, on an '88 V12, it'll be the 2.88 unless someone changed it

The simplest way is to buy Jag diff with the gears you want....but they can be a little hard to find. In the mid-late 70s a lot of XJSs and XJ12s used a 3.31 ratio. With a bit of luck you can find one. I was lucky enough to find one and had Coventry West overhaul it for me.

The Jag diff is a kissin' cousin to the wildly common Dana 44 differential. Lots of guys have simply bought what they needed from a differential supplier. There are some small details to watch for.....like bolt sizes for the ring gear....but's it's all "doable" with some research. There are threads in the archives covering the details, I'm sure.

Cheers
DD

 

I doubt anyone has touched it lol.

ya I was reading about having to change bolts and spacers I think. I see if I can see something stamped tomorrow.

Cheers

 

Sounds like a plan.... it would be great to go to 3.31 - this improves acceleration right, is it make a big difference?

 

I have been doing quite a bit of finding out about diffs recently. Because of the ratio changes, certain differential carriers (the bit in the middle that the crownwheel is bolted to and the pinion acts on via the crownwheel) are correct for certain ratios, and certain others are correct for others. This is because numerically higher ratios require a pinion gear that has a wider diameter than lower ones, and thus affects the position of the crownwheel relative to the pinion gear centre point. Carriers are readily available new, eg from: https://www.drivetrainspecialists.com/

Usually there are two versions offered of any given carrier: eg 3.73 & DOWN - good for a 2.88:1; and 3.92 & UP - good for ratios numerically above 3.92. Additionally the carriers come with various spline counts according to the output shaft of the car in question. The DANA Jaguar diff is a DANA 44. It has 30 spline outputs, positraction LSD, and the only difference from a standard DANA 44 is the output shaft arrangement which is unique to the Jaguar DANA diff. I believe, but I have NOT seen it for myself, that the GKN/Salisbury in the V12 XJS has a 19 spline output. I do not know if a 19 spline DANA 44 positraction carrier will fit into a GKN/Salisbury casing using the GKN crownwheel and pinion gears, but I expect it would if, and only if the bearings that hold the carrier in place are the same dimensions. I do know that the axle people I linked to above have supplied carriers for Jaguar GKN axles.

The GKN/Salisbury in a Jaguar V12 is a better more reliable diff than the DANA as fitted to the mid-1980s XJS V12. This is not to say that DANA 44s generally are inferior, just that the version in the Jaguar V12 seems to have a less reliable service record than the GKN. The reason being that the carrier's LSD system in the DANA fails more quickly than that in the GKN.

So a ratio change from a 2.88:1 diff requires: either

1. a replacement LSD diff from a 6 cylinder XJS with the desired ratio already in it (this is by far the best and easiest option) or
2. the existing 2.88;1 diff casing to be fitted with a new carrier if the ratio change requires different crownwheel spacing, and for that new carrier to be fitted with a replacement crownwheel and pinion giving the required ratios.

So in reality re-using your existing casing is not a good option as you have to replace absolutely everything inside it. far better to buy a second hand diff from a 6 cylinder car.

There are rather a lot of myths out there about the DANA in the V12. Here are two common ones that I have found to be mythical.
Myth 1: "it has a cone-type LSD" it does not, it has a plate type LSD just like the GKN, though not identical.
Myth 2: "it has 7/16ths diameter crownwheel fixing bolts where as a normal DANA 44 has 3/8ths" It does not have 7/16ths crownwheel fixing bolts, it has 3/8th like all normal DANA 44s. (The GKN/Salisbury in the XJS does have 7/16ths crownwheel bolts, and if you buy a new carrier for your GKN you can buy one with the 7/16ths holes already drilled, you do not have to drill them unless you buy a carrier with only 3/8ths holes.)

 

Wow great info Greg. Thank you. I'll look into it more once i get to the diff part of the rebuild. I'll ask my guy if he has any kicking around his junk yard. He seems to have everything I've asked for already.

I think the hardest part is gonna be getting those old bushings out of the trail arms. I've read you can "burn out the rubber and then cut the ring.

I'll be taking them to a shop to get the new bushings put in.

The mounts for the cage are in actual good shape so those wont need replacing.

 

Messaged the local jaguar guy and he has a diff already out. 3.31 ratio. So that's my best option I think. He just took out a 3.5 ratio for himself haha.

 

Removing the large bushes: get the blowtorch on the rubber and burn it out. the with a fine hacksaw, passing the blade through the hole in the centre where the rubber was and reconnecting it to the saw handle, cut through the steel outer of the old burned-out bush - but NOT through the steel outer of the arm! Then lever the cut ends up and get the cut steel outer out.

 

U sure you used 1/2 copper pipe because this pipe is not wanting to go in. I can get it to go in but I have to hit it super hard. So I'm stopping u til I hear back from ya.

 

how far I got it in. U can see where its rubbing

 

Figured it out after eating lunch. 1/2 copper pipe has an OD of .625". 3/8 copper pipe has a OD of .500. The sizes of copper pipe is based on the ID of the pipe not the OD.

So now I'm trying to find 3/8 pipe but I can only find 25ft rolls of it in copper. I'll look for other metals.

 

So after sitting I remembered I had some metal rods from a computer peripheral in the basement. Go measure. 1/2" OD. Yes. Both rods are 16" length. More yes.

I cut it to length.



5 minutes later done. Lol. I didnt have any string so used some wood dowel I had.

 

Check that the fulcrum casting bolts are tight, Rescue; often they are not.

 

Which ones?




Also are all the universal joints on the car the same size? I think they are but I'm just want to make sure. I'm going to replace them all with non greasable kind. I'll replace the 4 in the back end first. Then once I get the rear end back in I'll do the drive shaft ones.

 

I ordered poly bushings for the small one on the trial arm as recommended. Almost 100 cdn after shipping from superflex in the UK.

And I have access to a press at work but not sure what size dies they have to press the bushings into the trail arms. That's probably 2 weeks away anyways before I'm at that point lol.

 

The two bolts that hold the casting that is on the bottom of the side of the diff through which your copper pipes are going! These two castings provide the lower wishbone inner fulcrum. If you see number 33 on your diagram the casting near that.

The four in the driveshafts each side of the diff (2 each side) that connect the diff to the roadwheels and hubs are the same size. They are heavier duty than the ones in the propshaft (the shaft that connects the gearbox to the diff but as to their size I do not know.
The best driveshaft UJs I have found, and i have just fitted them to my car, are these ones:
https://www.rockauto.com/en/moreinfo...78726&jsn=2234 (greaseable) or these:
https://www.rockauto.com/en/moreinfo...78726&jsn=2233 (non greaseable).

I recommend either all four non greaseable, or the two outer non greaseable and the two inner greaseable. BEWARE not all makes of UJs are the right size, even through they claim to be correct for the car, but these definitely are.

 

thanks for the link.

Im gonna have to send you some Canadian maple syrup for all the help you have given me lol

 

It is a pleasure, Rescue, and no more than others have done for me, I can assure you, None of us was born knowing how to fix these wonderful cars.