At the local junkyard is a 89 XJS (vin 158000) that has the diff mounted speedometer. Since it's an XJS, I'm assuming it's a limited slip and 2.88. Can the housing of the LSD carrier with the speedo toothed wheel interchange with an earlier 3.54 differential to convert it to a diff mounted pickup?

I know the ring gear carriers are different thickness between the 2.88 and 3.54, I wasn't sure if the mating portion was the same for all.

 

If your read the help document it explains it. But basically it says to change the internal hearing you have to do reshimming and also probably a new carrier. It's actually cheaper to just buy a diff with the gears you want already in it and just swap the whole diff out. I found a 3.31 diff near me but because eif the covid I cant go it it. Wish I could because I have my cage out at the moment lol.

 

Just for clarity, I'm asking if the arrowed piece is the same between 2.88 and 3.54 differentials.

I've rebuilt diffs before, changing one or adjusting the shims is not a problem for me. The 3.54 I already have is very low mileage (57,000 km) and in excellent shape, I'm doing an engine/trans swap and a diff mounted speedo would make things easier. Mine currently does not have the toothed wheel for the speedo pickup.

 

Talk about doing things the hard, expensive way! I raced Jaguars on a MG budget by figuring out the cheap easy way to achieve my goals.
The fast, cheap way is to buy the whole rear end assembly from the restyled Jaguars with the outboard disk brakes. $300-500 at most Wrecking yards. Find one near you and see who will sell it cheap. 3:54 and you get rid of the cursed inboard brakes plus upgrade to single shocks etc.
Your emergency brake cables aren’t long enough so grab those too while you’re there.
All XJS will have the limited slip, All V12 sedans and many 6 cyl sedans as well. To check lift up the whole rear end until both tires are free of the ground. Rotate one wheel and if the other turns in the opposite direction it doesn’t have limited slip. If they both turn in the same direction it does.
if you insist on keeping those inboard brakes early XKE’s ( pre 1967) , Mk10 sedans 420S sedans all had 3:54 center pumpkins with limited slip. Some 3.8S did as well ( some didn’t have the limited slip )

 

Well, not quite. A bit more detail: I'm in Canada, and late XJS at wrecking yards are very rare. Those yards that do have them think they are made of gold and charge accordingly. The alternative is bring in a rear end from the USA and cross border freight for something like that gets very expensive, very fast. I've had quotes in the past and it was over $1K.

The car I'm putting this in is a Daimler DS420 Limousine, which has a semi fender skirt style body at the rear. The wheels just barely clear the hubs now when changing a tire, they would not fit over outboard brakes. So most of a late XJS rear end isn't of any use to me, aside from that piece in the differential. The car already has a 3.54 limited slip, and I can get the whole rear end from the 2.88 XJS at the local pick n pull for around $150, less if I disassemble it down to the diff in the junkyard.

So perhaps the hard way, but the cheap way!

 

Here's what greg posted in my thread when asked.

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.)

 

Canada does put a spin on things. Let me see if I can help you.
There is a Jaguar wrecking yard in Fredricsburg Wisconsin. I’m sure they would have the pumpkin you seek.
What is the maximum weight the post office will handle? Probably not enough, maybe send it parts at a time case, ring gear assembly. Side gears? to keep the weight below the maximum? same with FedEx and UPS. , hmmm international carriers? There must be busses that go from Minneapolis to near you. What is import duty going to cost and where do they collect it?
I actually have one on the shelf but I’ve got a home planned for that.

 

Thanks, I appreciate it! There are no buses west of Winnipeg now, Greyhound quit running in the west last year. Duty is minimal, 6.1% UPS is absolutely horrible across the border, their brokerage fees are ridiculous. My rule of thumb is if a USA seller only ships UPS I won't buy it, the UPS fees are that bad. For major things, one solution I have used in the past is to ship to the border at Montana and drive down and collect it. It's a 7 hour drive and the border is closed now anyway, so that's not an option. If the border was open, it's still a long drive to get something.

As I said, I've rebuilt diffs, taking one apart to swap parts isn't a problem, I already have a good shim collection! So in many ways, using the local parts car as a source isn't a bad option. At the moment I'm time rich and cash poor!

My other option is to use the output shaft speed sensor of the 4L80e transmission and then use a Dakota Digital box to change the signal down to the 8000 pulses per mile the Jaguar speedometer needs. I'm swapping the original XK 4.2 engine and TH400 trans for a 6 cylinder XJR engine and trans. I saw the XJS at the junklyard and went Hmmmm.....

Regarding gear thicknesses, the piece to the right of the arrowed piece in my photo is different between 2.88 and higher gears, I know that. That's the carrier difference, that flange that the crown gear bolts to is different. However, I have the correct one for my gears, so as long as the mating (arrowed) piece is the same between 2.88 and 3.54 then it's a simple swap. All I really need is the sheet metal toothed wheel that is pressed on, my existing 3.54 doesn't have that.

 

The Daimler 420 gets me. If I recall the axle shafts are just a few inches shorter than the shafts on the XJ series. (with attending lower A arms)
so if you used your axles and A arms on a newer rear end you’d wind up at the same width ?

I think if you measure out to out on your”frame” Rails and I measure the same thing we might have a solution?
That is use the new style rear end assembly with your axles and A arms? May as well measure center to center for axles and lower A arms.
you’d need to press apart the U joints on your axles. To make sure everything would swap back and forth.
I’m in Minneapolis Minnesota. What does your GPS say is the distance between us?

 

Not the 420, which is based on the Jaguar 420, it's the DS420, which is a Mark 10 floorpan stretched 26". IRS is the same width as the XJ6/S. Some pics (not my car though)
DS420 Lewis Brothers pictures (l)
DS420 Lewis Brothers pictures (l)

Distance between us is 1200 miles. With the Covid stuff the border is closed right now, so I couldn't visit you even if I wanted to!

 

Then the later wheels must have less back spacing or are wider? ? I’m sorry I don’t know why your old wheels wouldn’t fit on a later rear end and still clear.
Please realize I’m a racer and if bodywork is in the way I take a hydraulic jack and gently stretch it to make it fit. I’m not taking Group 44 sized flairs. Just a subtle massaging.
I’m spreading the fender while retaining the stock appearance. ( use a small bottle jack, a piece of 3/4 inch plywood on the inside and a 2x4 pushing against a sand bag on the outside. The one I use is made of really tough leather and I’ve moved the fender out more than 2 inches without cracking the paint or ruining the body lines. you gently move it tiny bit at a time working back and forth across the wheel opening. Don’t get greedy, move it a little and carefully check.

I understand with a collector car of that nature maybe you can’t do that? You’ve already made some compromises to originality. But why can’t you use the later rear end in an earlier chassis if you use your wheels? If they are still too wide couldn’t you buy a wheel with more back spacing? Isn’t the XJS and XJ12 / 6 the same width? Didn’t the updated cars just increase the width of the rims? I realize you want a speedometer to work in that set up.

1200 miles hmmmm. 1/2 way is only 600

 

Then the later wheels must have less back spacing or are wider? ? I’m sorry I don’t know why your old wheels wouldn’t fit on a later rear end and still clear.
Please realize I’m a racer and if bodywork is in the way I take a hydraulic jack and gently stretch it to make it fit. I’m not taking Group 44 sized flairs. Just a subtle massaging.
I’m spreading the fender while retaining the stock appearance. ( use a small bottle jack, a piece of 3/4 inch plywood on the inside and a 2x4 pushing against a sand bag on the outside. The one I use is made of really tough leather and I’ve moved the fender out more than 2 inches without cracking the paint or ruining the body lines. you gently move it tiny bit at a time working back and forth across the wheel opening. Don’t get greedy, move it a little and carefully check.

I understand with a collector car of that nature you can’t do that. But why can’t you use the later rear end in an earlier chassis if you use your wheels? If they are still too wide couldn’t you buy a wheel with more back spacing? Isn’t the XJS and XJ12 / 6 the same width? Didn’t the updated cars just increase the width of the rims? I realize if you want a speedometer to work in that set up you’ve already made compromises to the originality.

1200 miles hmmmm. 1/2 way is only 600 that’s about 10 hours. Maybe we can find something to trade?

 

Wheels are the stock 15x6 Kent alloys that were used on the Series III XJ6, but with a hubcap. In the photo of the rear, notice how low the rear fender line is? It's below the top of the rim. The early (1968) cars had slightly narrower tires, then they went to 235 tires ( the same ones as the Rolls Royce Silver Shadow) in order to handle the weight of the car. The tire can just barely slip between the fender and the top of the hub when changing the tire. Offset when mounted isn't a problem, it's getting the tire on an off, the suspension has to be at full droop to give enough clearance to change a tire. That's the reason I couldn't use outboard brakes. Even spreading the fenders a reasonable amount wouldn't give enough extra to get the tire through the gap.

All that being said, I was talking to an friend of mine tonight who is an Electrical Engineer and he figures it's easy (for him) to design a signal processing circuit to convert the output shaft speed signal to what the speedometer needs. Certainly less work than taking apart a diff, so I'll explore than avenue first.

 

So was the original motor the iron block 4.2 six?
what carbs did it have? Do you have any left?

 

Correct on the engine, carbs were SU HIF44 with manual choke. They have gone to a friend with a stromberg equipped E Type.

 

Darn I’m looking for one HD8. I’m building a tribute car but want to get away from fuel injection. Just to difficult to modify The stock fuel injection system.

 

Have you looked at ebay.co.uk? You can often find SU's there at reasonable prices.

 

Great idea. Hadn’t thought of that.
what would shipping be? SWAG ( scientific wild azzed guess. I mean are we talking $10 or $100?

 

The listing will always show the shipping price. The Royal Mail is actually quite reasonable, I almost always find postage from the UK to Canada much cheaper than USA to Canada for example. If you want do a currency conversion www.xe.com is a good resource.

Also consider HS8/HIF carbs over the HD8, the HS will be a lot cheaper it seems and work just as well.

An example listing, postage is £23.75
https://www.ebay.co.uk/itm/Classic-S...MAAOSwVA9eV-tL

 

yep SNG Uk is cheaper than the USA warehouse