89 XJS v12 (Marelli) 5 speed swap

Northern car with ripped top. PO had new carpets installed years ago but never removed original. So, 2 layers of carpet didn’t help things. Lots of water damage. As you can see the driver’s side jacking point is a little sketchy. 134000 miles motor has more oil on outside then inside.
Windows don’t function neither does top. Still has a fair number of good parts so I I’m going to dismantle and store them. Bumper chrome, dash pad and wood are very good (better than my project) so I’ll be swapping those. Body panels, glass, chrome, motor, and F/R suspension assemblies I’ll store and sell.


Wanting to get rid of my cell phone hole and the pillow I stuff in there, I bought a black “lid” off of eBay, and sent it to Paul’s for a recover in the original barley leather. Out and back in a week. No affiliation, just a satisfied customer.

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I love that place. I always enjoy just shutting my trap and listening to Jeremy go on about “x” topic, a very cool guy.

Lid looks awesome BTW.

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Quick update: First extended (90 miles) highway trip yesterday. Car worked great, got up to about 115mph, super smooth. A lot of fun in 4th gear at about 4000 rpm/90 mph.

I am still a bit shocked at how much cooler it runs. I’ve made this trip many times so I have a baseline. Temps of 200-205F would be normal. The car literally never got above 190, even pulling a long hill on the floor in 4th. (There was a passing lane. Not gonna let that go un-used.)

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I just don’t remember- did you leave the auto/radiator in place, or replace it?

Very interesting - the silver bullet. Reason 276 that Jaguar completely misread the US (global) market and should have offered a manual.

Thanks for the continued updates.

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The auto radiator is still in place, zero changes were made to the cooling system pre-/post swap.

There have been reports before that an overheating V12 was actually caused by excessive heat from a GM400 that may or may not have been malfunctioning in some undiagnosed manner.

Never saw any sign in function or fluid contents/color/smell that my trans had an issue. It only had 62k on it. And my car didn’t overheat. It just ran warmer. But we know that auto transmissions generate a lot of heat even when working properly. I just never thought it was this much heat.

Stop and go traffic can definitely heat up the atf, which heats up the coolant, so sounds quite normal to me.
And how hard Jaguar made it to drop pan to change ATF, I’ll bet a lot of XJS’s are running old ATF, which heats up even quicker and higher temps.

Hey Bob, any updates on the 5-speed swap? How is it behaving?

I’ve had some throw out bearing issues which I’m pretty sure are my fault. I will update this thread once I have it handled, which should be within the week.

Funny you say that. The prior owners had clutch slippage issues. There was no pedal stop and the return spring had been shattered. Thus, over extension of throw out bearing causing many issues. They tried. That being said I think the mating surfaces (between the throwout bearing face and pressure plate pedals is very critical).

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Which you know. Just digesting. Triumphs and MGs were so much easier

I’m assuming you have a hydraulic throw out bearing. If so, have you seen this?

Yes. How I set up the pedal stop is all detailed in the thread above. I use a similar technique to the video to get initial release point, for final I set it up so when idling the trans just goes into reverse with a minimum of fuss. If the stop is just a bit too high you can slip in the fwd gears but not reverse.

So, here’s the latest. I ended up with a TO bearing leak. Very very frustrated to say the least. It appeared to be the seals, not the lines or anything related to the MC. Went out one morning and had no pedal.
Step 1 was to rebuild one of my spare bearings so it would be ready to go in. RAM sells seal kits. During this process I discovered that there is a “Heavy Duty” version of the 78125 bearing, PN, (wait for it) 78125HD. The difference is two teflon? wipers, outboard of each o-ring seal. I like this better as I think it will keep dust and junk away from the o-rings. SO I bough a 78125HD. It is shorter still, so I remeasured and added a couple of spacers to the nose of the trans. Here is a video of the 71825HD rebuild, you can see the additional white wipers.

During the rebuild process (of a bearing that I used to fit things up, but was never installed permanently, the car was still together at this point) I noticed gouges on the sleeve of the bearing.

This is not cool and can only have happened from me scraping the nose of the bearing on the clutch fingers during install. SO this one one thing to look for on tear down - did I gouge the bearing in the car?

Next I built a cradle for my jack which holds the trans perfectly in alignment for removal / install. I did all the fitting with the trans in the car, the idea being that the trans should slip in and out very easily. It worked well and the trans came out fine. I was quite grumpy during this whole process.

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The next thing to check as a possible root cause of the failure is the TIR (total indicated runout) between the bell and the crank. You’ll recall I measured at .01 during install. Well, .01 is the generally agreed upon maximum allowed for TIR. I had in my head that it was something like .02. Had I know I would’ve done better.
Once I got the trans out I purchased a smaller dial indicator and came up with a couple of big washers so I could clamp onto the clutch fingers and have a solid platform for the magnetic base.

Mini dial indicator and magnetic base (from McMaster):

Giant fender washers (from McMaster)
You can also see my “notes” on the bell. Note that 0 and the max (5) are opposite each other, which is what you should expect. At this point I was getting pretty close to my .0045" final TIR.

A proper dial-indicator set up with the probe parallel to the mating surface and perpendicular to the surface being indicated.

Saw many of these at a motorcycle dealer years ago.

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