🔧 BUILD 1984 Jaguar XJ6.0

[nsogiba]

I got the SGI100BT installed and am having trouble getting the tach working. To verify that the actual tachometer itself works, I hooked the tach signal from the Holley directly up to the tachometer (no SGI100BT). It works and reads rpm (although low). Keep in mind I have the 330ohm resistor soldered in per the following link

http://www.jaguarspecialties.com/tech_tips3.asp

With the SGI-100BT installed inline, the tach doesn't work. It has a good 12V switched power source and ground and turns on with the ignition. When I hold the SET button with the engine running it shows a number bouncing between 048 and 052, which rises with RPMS. I assume that means it has a good input signal from the Holley. I confirmed this by verifying that I have a 14V AC signal on the input wire from the Holley. However, the tach still does not work. I tried both the Normal and High Voltage outputs per the diagnostic guide but didn't have any luck.

So in summary, I know I have a good input signal and a good tachometer.

The only thing I can think of is a setup error that I'm missing, or that the tach has a 330ohm pull-up resistor soldered in.

 

[nsogiba]

After putting the kids to bed, I spent Saturday evening tinkering with the tach. I snipped out the resistor and resoldered those leads, returning the tach to OEM spec. Just for testing purposes, I left the tach loosely installed with the signal wire hanging loose.

I fired up the engine and was met with a working tach! After a few minutes comparing the RPM readout on the Holley handheld to the analog tach, I used the Dakota Digital app to apply a correction factor and bring them in line. Success!

 

[nsogiba]

The Christmas miracles continue. I enabled the speedo output in the Holley with the default 4000ppm signal, wired it up, and we have a speedo!

I did have to apply a correction factor of 2.0 via the DD app which means that the Jaguar speedo is looking for a 8000ppm signal. Now, I need to figure out what I want to do with the rest of the auxiliary gauges (fuel, temps, etc) and clean up this mess of temporary wiring.

What an awesome feeling seeing the OEM tach and speedo just "work".

 

[Five-0]

This build is awesome! Great work man!

 

[nsogiba]

First "issue" with the car since the swap was done - original diff gave out. I was coming home one night and started to hear a knocking from the rear end consistent with vehicle speed. Figured it might be a driveshaft issue, but decided to chance it and limp the car home.

The chassis is an '84 with 172K on it, but the rear end assembly has "85 XJ6" written on it in ink marker so I am assuming it was swapped out some time in the last 39 years. No clue on the mileage on it though.

Drained the diff. This gear oil has only a few thousand miles on it.

The rear end comes out as an assembly so 2 hours later I got this.

The folks in Quality Assurance came by to check my work

The culprit is the retaining pin that holds the cross shaft in place, which walked out and allowed the shaft to knock into the pinion.

Pinion took a little beating

It's a shame because I think the 2.88 ratio suits the setup very well, so I am reluctant to regear. The damage is in a non contact area so maybe I'll deburr the pinion teeth and see how it runs.

I hammered out the cross shaft (shouldn't have to do that) and found that it had pretty bad galling on the spider surface. Definitely a lack of oil at some point which caused it to get mega hot.

I actually had to hammer out the cross shaft halfway, cut off the exposed stub, then hammer out the remainder as I obviously wasn't able to pull it out with the carrier flipped.

Thinking back, when I dragged the car home it was on the back of a tow dolly since there were no car trailers available due to Covid madness:

Even though the original trans was probably going to be scrapped, I still unbolted the driveshaft from the pinion flange so that it wouldn't cause anything to seize up and lock up on the thruway. Once I got the car home and up on the lift for the first time, I drained the diff and only a few ounces of gear oil came out.

My theory is that it drained out due to a bad leak on the driver's side output shaft while in storage before I bought the car, it got very hot on the way home, and then I continued to beat it to death with new oil for the next 2 years behind the LS.

Game plan - try to salvage the ring and pinion, order an Auburn locker, replace bearings, and put it back together. I'll also check on the condition of the output shaft bearings, hub bearings, and various seals while I'm in there.

 

[Mr_Roboto]

How rare is a pumpkin for something like this? Anything else swappable really? The Caddys seem to be using 8.8s but man that is an expensive setup.

 

[nsogiba]

You can't really find these cars in junkyards but you can find them on marketplace in various states of decay. Luckily my pumpkin (diff housing) is fine, I just need a new carrier, so I'll be upgrading to a Eaton Truetrac.

 

[Mr_Roboto]

Guessing the internal bits are something not too oddball if you can get a Truetrac for it.

 

[nsogiba]

It's all based on the Dana 44. The diff itself is strong, mine just ran out of oil at some point. It doesn't owe me a thing

 

[Mr_Roboto]

Aaaah, that's awesome. Easy to source parts for and probably will be until the end of days unless they have 500 weird variants like they do with the D30s.

 

[nsogiba]

Aaaah, that's awesome. Easy to source parts for and probably will be until the end of days unless they have 500 weird variants like they do with the D30s.

Unfortunately that's mostly true. Most Dana 44s are 30 spline output, mine is 19 spline oddball stuff. I have a lead on a shop in Detroit that apparently specializes in this stuff, we'll see what they say

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[nsogiba]

Made a video about my last build, 2011 Crown Vic with the turbo LS. Give it a watch!

 

[nsogiba]

Getting apart the IRS was dirty, tough work. This chassis is remarkably rust free but it seems the rear end was worked on at some point since I found evidence of a rebuild in a few spots. Driver's side hub carrier assembly missing the bronze phosphor spacer ring (huge endplay), the words "85 XJ6" written in paint pen on that same carrier (this chassis is an '84), and some missing tie wire.

I spent the better part of a few weeks trying to get the hubs out of the carriers. My person 12 ton press and a friend's 20 ton press were defeated even with the use of a torch to melt the loctite on the splines; it took a 50 ton press at a heavy truck shop to get it loose. Unfortunately the end of that hub was damaged beyond repair, but Dave @ EverydayXJ saved the day with a spare.

Another week was spent beating/pressing off races and bearings and cleaning. Both my carriers exhibited the cracks that seem to be present as a result of the casting process.

I dropped those off for welding and reinforcing, and while I was waiting busied myself with other items.

Originally I wanted to reuse my 2.88 ring and pinion since the long gears were great on the highway and loaded the engine nicely, which helped spool the turbo. Since the original 2.88s were destroyed when the open diff let go, I purchased a used set of Jag 2.88s from DTS in Detroit. Unfortunately, I found out that these gears are not compatible with the Auburn 546085 19 spline Posi limited slip. They physically bolt up to the differential carrier, but the flange is too close to the pinion and will not allow the carrier to be mounted.

I have to give credit to Bill at Rear End Specialists, who worked with me to find a solution. He was patient and welcomed the challenge as he had not done a gear and carrier swap in a Jaguar Dana 44 before. I recommend his services.

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A well known shop local to me, Denny's Driveshaft, came through with a new set of Dana 3.54 gears and the required 26 spline pinion yoke. They are located 10 minutes away from my axle builder, so no shipping was required, and Bill picked up the parts from Denny's for me. Big thanks to both shops for helping me out.

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Once I got the diff back, I started the process of building it up. I rebuilt the output shaft assemblies with new seals and installed the rotors/calipers.

The diff cover got cleaned up with fresh paint. I noticed that the breather vent had some mangled threads, so I welded in a stainless 1/8" NPT elbow for the vent to mount to.

I designed a set of conical differential to cage mounting sleeves. My OEM bolts on top of the cage were tight, but I figured this was an easy way to ensure the diff wouldn't come loose due to the lack of thread engagement with the OEM bolts.

1/2"-13 threaded studs were trimmed to size, installed with blue thread locker, and self locking nuts installed on top of the new spacers to ensure alignment.

Winter is wrapping up here in Buffalo, so I got my other fun car out of storage and ready for the warm season. The summer is the first where my son is old enough (2) to face forward, which makes it much easier to load him into his seat. He and my daughter cannot get enough of "Blue Car".

Next up: Axle carrier rebuild, full u-joint replacement, fulcrum shimming.

 

[Gav'sPurpleZ]

great write up / documentation here.
I have order from Denny's Driveshaft for my Camaro. Their website is very helpful, prices are good and always have fast shipping.