Well I managed too get my hands on a nice m21 I dropped it off to a very good friend of mine shop too be bulked up a bit . What will I need too do too adapt this transmission into my car?

 

Well I have a new slip yoke for it and the bell housing from fives peeds web site , what is commonly adapted for the resivour ? I was told by n old timer too use one from a 4th gen camaro

 

I’m a racer. So I can’t answer a lot of your questions but here’s the good news.
You need a Chevy 350 bell housing. If you are never going to race the production one will work. If racing is a possibility buy a “scattershield” from Summit or Jegs etc. ( or racing Junk )

you aren’t home free yet.

The alignment pegs on your V12 will match your bell housing but none of the bolt holes will align. You need to build a spacer. But that’s a couple of steps away.

What you need to do next is measure the input shaft with a micrometer and buy a ream that size. ( do not attempt to use a drill bit)
Carefully ream the pilot shaft bushing you buy for a manual transmission XKE series 3. And slide it over the pilot shaft. They aren’t very expensive. I don’t know if a Chevy bushing will fit or not.
oops I’ve gotta go, I’ll continue as soon as possible
The. next step is to slide the transmission all the way in. Leave the bell housing off. With the flywheel and clutch assembly on measure from the block to the throw out bearing. To that depth add 1/4 inch. ( .250 ). Now measure from the block face to the front face of the transmission. Add the 1/4 inch ( .250 )
from that you know how thick a spacer you’ll need ‘
most turn out to be around 3/4- 1 inch think.

 

Just a heads up here, look very carefully at the transmission tunnel on the Jag,. I played with these transmissions for many years long ago with Chevy powered Datsun Z's and more. The big issue I think you will face is the shifter. The Muncie uses an external shifter and rods, all mounted on the driver side of the trans, and it is a pretty substantial piece of metal. That will be sitting right where the Jag trans tunnel is getting very narrow, so to make it fit, I expect you will be cutting/sectioning/welding the tunnel in that area. There was one Chevy converted XJS done years ago using a Doug Nash 4+3 manual trans (the unit used in 84-87 or so Corvettes) and it was essentially a BW Super T10 with an overdrive on the back. It's T10 origins go back the Muncie days and and external shifter which required a lot of tunnel rework- it was a big deal and noticeable inside the car as well. In this case, trying to put this behind a V12, the trans would be even farther back, so I'm wondering if it would be even tighter....

On paper it sounds like an interesting swap, but in reality it may be quite the can of worms

Good luck

Andrew
Jaguar Specialties

 

Once you have the thickness of the plate
Same deal, tap out a pilot shaft and then using a micrometer measure the diameter.
drill slightly undersize then ream.

next you’ll need a hand full of transfer bolts. They are little bolts that screw into the block and stick out about an 1/8th inch slide the adapter plate onto the dowels and using a dead blow hammer transfer the holes in the block to the adapter plate. You’ll need counter sunk Allen head bolts.
Now using the bell housing drill and tap holes into the adapter place drill and tap for bolts.
it may sound complex but I can do that in a weekend morning. Buying the reams, and transfer bolts if you shop carefully you’lll spend less than $50.

 

Andrew you are right. That Corvette overdrive transmission ( Borg Warne) has a bulky shifter and is long. Plus the syncros are very weak. The Muncie is much stronger , and the M22 even more durable. Plus with the stock 2:88 rear end, very hard to get off the line. Frequent clutch replacement is the result.

If you switch the whole rear end to the later outboard disk brakes assembly instead of 2;88-1 you wind up with 3:54. The good Dana 44 instead of the slightly weaker Salsbury. All rear ends from XJS have limited slip diffs as do some of the XJ6 & all of the XJ12’s. the going junkyard price is around $500 for the whole assembly.
While you won’t go 150 mph anymore. ( new top speed about 125-130 mph). Good news is It will make the Jaguar come alive. Gives the V12 really decent acceleration instead of the casual rate it has with the 2:88-1