89 XJS v12 (Marelli) 5 speed swap

Before I loosened the bell, I took a reading, expecting to see .01. Nope. More like .02 TIR. Really really bad. RAM makes a very big deal about getting this right in their literature, The seals in the TO bearing cannot tolerate being “wallowed” by a mis-aligned bell/trans.

SO, now we need off-set dowl pins so that I can properly align the bell (again.) These are available from a variety of sources. GM standard diameter is .625, which is what my V12 had (possibly due to the TH400? I feel like Dad’s 71 V12 used smaller dowels… don’t recall.)

There are several videos on youtube showing how this process works, so I am not going to beat it to death here. BUT the key thing I learned, and that surprised me, was that you need to torque the bell all the way down before you measure. I was surprised that measuring torqued vs un-torqued changed my TIR by as much as .01. I guess there are things not perfectly parallel, maybe the bell is warped a bit, who knows. After a lot of trial and error, I used a set of .007 offset pins and achieved a TIR of .0045, which should be fine.

(Dad’s Etype uses a Quicktime bellhousing, and one of their claims to fame is they are very accurate. His measured about .0025 with no offset, so their claim held water in that instance.)

To pull the factory dowel pins I ran a fine thread 1/2" tap into the center (they are hollow) and used a bolt and socket to draw them out. They were really in there.

The new GM pins were a touch too long (the shoulder protruded) so I shortened a bit.

I put them in with loctite, although once the bell is torqued they don’t do much. But still I don’t want them loose.

One other item of note, when I off-set the bellhousing the first time, bolted it up and turned the motor (with the flywheel turner) it felt horrible. Like something was grinding. It kind of freaked me out. Turns out the flywheel teeth were contacting a high spot on the bell. Not much clearance in there. Broke out the die grinder and removed some material, all good.

I examined the TO bearing I took out, no gouges, so that would not have caused the leak.
I also had Rene help me check the total travel of the bearing, unloaded (should be the same loaded, not accounting for hose or seal expansion) and confirmed that it is about .1 less than the max travel of the bearing. So it would appear that over-traveling the bearing was not a root cause either. I think the poor bell alignment was the smoking gun. Time will tell.

The trans went back in very nicely (the cradle is the bomb. Hope I don’t need it again for a long time.) and everything else was same as the first time.

The car is running good and the trans feels great (like it did the first time) so fingers crossed that we can go on to more fun projects. (The trans project was fun the first time. Not so much the second.)

Thanks for the update Bob.
My 89 parts car is totally dismantled and shell is ready for it’s new adventure. Now I can pull the fuel tank and repair a fuel leak on my 86. Also sent a log to Omex (ecu) and they want me to change the location of the coolant temp sender and check wiring for my o2 feedback. Then I can put some miles on and see how she behaves.
I’m thinking later this year I’ll go after the 5 speed conversion and this write up you did is going to be of great help. Thanks again

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Good to know the bell was adjusted in, now, and you know it.

Are you sure the leak was from the bearing seals? I ask because when I did a 5 speed install, I ended up with a leak in the clutch line. Here, a custom bent piece of tubing was connected to the hydraulic release bearing, and made it out of the bell and up toward the top of the engine for about 6-8 inches. From there to the clutch resevior, a braided line was used. The flare at that hard line coming from the bell was slightly imperfect, and I developed a leak at that connection.

In this case, the fix was impossible to do without dropping the trans- could not reach that fitting except with a basin wrench, and manipulating bits in place all but impossible. I tightened as much as I could, and have left it for future resolution- a small amount of fluid leaks, but not a major problem- top up the fluid about twice a season.


Yes, I could see the leak thru the inspection port. My line is single piece braided from the reservoir to the TO bearing. I have had leaks at fittings before, but not this time. Curious how you used a hard line to the release bearing? On the RAM and McCleod bearings the fittings move with the bearing, so a flexible line is needed. Maybe others have the fittings in the stationary portion.


I probably missed your observations probably already reported earlier in this thread- sorry about that!

Yes, the bearing on my trans has the hardline attached to the base of the bearing. Not sure which brand bearing this is, it was supplied as part of Keisler’s very earliest production of the TKO kits for the XJS. I got this kit from a fellow JL member who had bought it in a group buy, but never got it installed.

Frankly, that arrangement makes more sense to me. Most of the OEMs have gone to hydraulic TO bearings, like in my late model Mustang. These things seem to be completely bulletproof. I believe they use a hard line at the base as you describe.

There are a bunch of different orientations, and one thing that could make the hardline more difficult to accommodate would be installing the bell first and then the trans, which is usually my preferred approach. It’s easy to sneak a braided line through things, a hard line not so much. There’s many many ways to skin this cat.

The one I picked up from the 89 parts car is the same. Throw out bearing assembly bolts to transmission with 2 hard lines for hydraulics. According to paperwork installed originally around 2004 (Keisler).

Hey Bob great updates, I only have one further request.
Can you please do a step by step (including pictures)
On how to install a backwards mounted leaper hood
Ornament on an XJ-S? Much appreciated, thank you.


Backwards Leapers are old news. I’ll do a thread on putting one of these bad boys on. OK to use your car for this project?


Good point Bob, I was only messin . But hey got ask.
I think if you ever did one it would be the second best one
I ever saw!

Lol all good! I was tryna be funny!