Mike,

I have a TKO600 & the input shaft diameter is 15mm. The ID of the jaguar pilot bush that I obtained is 12.78mm, so the pilot bush needs reaming out by 2.22mm - as the "walls" of the bush are only 3.10mm thick, I thought this would leave the bush too thin but I don't think it's a good idea to have the input shaft turned down to suit the bush. The OD of the bush is 19mm but as I have not yet removed the GM 4L80E from the rear of the motor, I do not know what the size of the recess is in the crankshaft.

Regards

Andy.

 

Andy:


You have stumbled onto another one of the differences in the kits and the Jag v12, and that is, depending on whose kit or trans you are using, the bell you are using and the model year engine these are to go into, you need to know the bearing needs.


What I mean is this: the trans I am using, a TKO, was delivered as part of Keisler's kit. This is a trans set up for a Ford application (had a Tremec factory tag saying FORD on it), but I believe had a modified input shaft (Keisler). This shaft is set up, together with the bell housing (depth, now) such that the tip of the input shaft pilots the inner most hole in the crank. This is the traditional pilot bearing hole we have been talking about. I do not know whether Keisler shortened this shaft in addition (I think they may have, because I want to recall that I measured the input shaft length and compared it to a Ford spec and they were different...) to turning down the piloting end, but either way, I think the input shaft on these boxes were modified by Keisler as part of their 'kit'.


Later Keisler kits, and the DM kits, supply a different bearing: this bearing fits into the next outer bore of the crank, where the torque converter nose was piloted, when the autobox was used. The bearing that fits in that pocket is a roller bearing, and it has a center hole that is used to pilot the input shaft. In this case, the shaft is shorter (or the bell is taller, I do not know which), and the diameter of the tip is suited to the ID of the roller bearing.


Confused? I know I was before I sorted all this out.


Your pilot bearing (the one you described to me) is the typical sintered bronze bearing as was used in the E-type V12 manual boxes and early XJS manuals. On my kit's trans (Keisler TKO), that bearing slid ever so finely onto the input shaft end. It was the bearing's OD that was the problem. I bought this same bearing and had it machined down with the interference required.


The bearing that I just described above, though (the roller bearing one) looks ALOT like a pilot bearing for a GM product. Check Summit or the speed parts supplier catalogs and you will find a picture of what I am talking about. A bearing of this type was used in the later Keisler and DM kits. You can see it in the kit pix of DM, for example.


I am guessing that this later approach to the pilot bearing enabled the kit makers to specify an off the shelf trans (e.g., NO input shaft mods were required). Like I said, though, there are two things to watch for: what the bearing needs are, and how long that input shaft is, and where (how far, that is), when it is on the bell, does it come into the crank.


Either way, if you are doing this by gathering components, you will absolutely need to make measurements of the input shaft length, diameter and the bell height. Then, make measurements of where the crank face sits with respect to the rear of the block (where the bell mates). All this will enable you to sort out where that input shaft is going to land, and therefore determine what type of bearing you will need.


It's all very tedious, because we are not just dealing with a straight GM or Ford where everything just fits (most of the time).


-M

 

Based on the experience of another who has done their own conversion (more than once) & helped with several others, I bought the GM TKO600 with the 26 spline input shaft as I am told it is the correct length.


I've noticed that bearing in the DM kit picture & I'm on the look out for a scrap (read, low price or just plain dirt cheap) 6.0ltr engine so that I can check out the rear of the crank & hopefully establish what the size of that "pocket" is & then source a roller bearing with the correct OD & a 15mm ID for the GM TKO600 input shaft.


That's exactly what it is but even before I know what OD is required for the crank, leaving the wall of that bearing only 2mm thick felt like it would be ending up too thin.

That's a good shout & I will check out Jegs & Summit etc to see what I can find.


My bell came from DM via a helpful chap in the USA & I've placed it on the front of the TKO & the input shaft does protrude - I can't recall exactly how far but it didn't seem excessive & it didn't seem insignificant if you know what I mean.

Again this would be an advantage of getting hold of a scrap 6.0ltr engine. I am told that the crank protrudes 4.5mm +/- 0.5mm from the rear mounting face of the block.

Again, thanks for taking the time to reply. I am determined that this project will be completed & to a good standard of drive ability.

Regards

Andy.

 

Andy:


OK, I found some pix to explain the issue. The first is a photo from a fellow I know in Canada who adapted a Supra transmission to the V12. This adaptation used the conventional bronze bush in the inner most hole of the crank. You can see clearly in this pix the much larger OD pocket I am talking about (the annulus around this pocket is maybe 1/4" thick). In this case, the bushing was protruding quite a way out of the hole to deal with the shorter input shaft or too tall bell, and the bell to block misalignment eventually caused the bushing to fracture. He eventually made an adapter that fit in that pocket and held a new bronze bush.


My bronze bush is similar in that it is fitted to the center hole, but mine was driven completely into the crank, so that none of the bush stood proud from the crank flange. This is typical of the OEM V12 manual transmission bush setup.


The next pix are from a guy I know in South Africa who did a Kiesler/DM kit on his 1980 XJS, and here we show the actual bearing supplied. Note the roller bearing configuration, and that it is fitted to a larger diameter spacer. The other pix shows this bearing sitting in the pocket I have talked about. I know another fellow in Uruguay with a 1990 XJS whose install is the very same configuration (have the pix on this install, too).


I think this crank detail is the very same on a 6L motor; I am sure if I scour about I will find a 6L crank pix that verifies this.


What IS different among the 6L motors is the diameter of that inner-most pilot hole in the crank. The early cars have one diameter and the later (post 89) cars use a different diameter.


There was a case of an early Keisler kit installation on a 1990 that was done by a contracted mechanic for an owner. The mechanic, upon finding that the pilot hole was too small for the bush, used a die grinder and hogged out that hole and then shoved the bush in. That resulted in fearsome vibration and a very unhappy owner, and a three-way set of allegations began, ending with Keisler taking the car and fixing the botched install. You can read about this in the Jag-Lovers lists. This is the first recorded instance I could find that showed the post 89 cars used a different pilot bore diameter. That was also the case on my '90.


If you want the actual figures, I will check my notes from the installation to find the values.


The point is three-fold: first, the pilot tip diameter can be different for the two bearing types. Second, the depth of penetration of the pilot shaft is different for the two types. Third, the inner-most pilot hole diameter varies with the production year of the engine. Measure yours to be sure of what you've got, if this is where your bushing will be going.


-M

 

Um, I miswrote when I stated:


"What IS different among the 6L motors is the diameter of that inner-most pilot hole in the crank. The early cars have one diameter and the later (post 89) cars use a different diameter. "


What I should have said was this:


"What IS different among the v12 motors..."


And I should have added: I do not know the pilot bore diameter for the 6L motors.


My experience and that of those with whom I have met and/or corresponded was strictly from the 5.3L motor, both pre and post '89.


Sorry about that.


-M