I beleive it is a Jeep bellhouse. I have not removed my TH400 yet but all of the pics I have seen are simmilar to Jeep a round bellhouse.

 

too bad chrysler mexamatic transmissions are ****ing garbage.

 

Don't Chrysler use the NAG1 WA580 (aka Mercedes 722.6)

 

The Jag TH400 has the same dowel pin location and IIRC two of the adjacent bolts are in the same location as the Chevy V8 pattern. THE BOP pattern also shares the dowel pin location and the four lower bolts are the same as the Chevy. That makes it a lot easier to fab an adapter.

 

mustang,, been there done thet 15yrs ago, exactly why i used a BOP adaptor plate against the Jag block, THE ALIGNMENT DOWELS, also aligns with the 4-6 spd GM trans.

but has to be a 1978 up V12 block, to much work trying to make early 12 work(wrong dowels locations).

gotta love GM parts interchanges , it goes all the way back to 1955 chevys.

FYI, the TOYOTA Nascar engines use the 55 chevy bolt pattern also, go figure!

that TCI piece is a great unit ,but $5K ,you aint gonna find many stepping up to that!

 

That Toyota engine is a peculiar thing built to N-***-CAR rules. pushrods, carbs,.....not related at all to anything Toyota builds or sells....Someday they'll get back to their STOCK CAR roots, I hope.

The only caveat to using the adapters is to check concentricity between the crank and the trans. Most specs only allow up to .005 -.006" of runout and when you start stacking stuff it adds up fast.

Yeah, that's a lot of $$$ for a trans. It's an interesting approach on computer controlled gear splitting, though. It's really just a four speed 4l60E but they get six speeds by engaging the OD thru the range. 1st, 1st-OD, 2nd, 2nd-OD, 3rd, 3rd-OD. That's how the others get to seven and eight speeds. It's a nice close ratio set.

OTOH, you'll have that much or more in a six speed manual conversion.

 

good info about usin the overdrive to split gears!

and if i were gonna do it over again, YES i would use a 6spd manual.

very few people have ever driven a jag V12 with manual trans, i have!

and it is an encredible experience, nothing like a V8, V12 with its long flat torque curve.

 

manual transmissions are more fun, A LOT more fun. and that justifies the expense.

 

jag only bell housing


use the john's cars quarter breed v12 to GM T700 swap kit...
then go buy the TCI 1992 camaro 6 speed conversion
oopppsss.... you got a 6 speed behind your V12
I think the drive shaft they (John's cars) sell for it should work too, but you will be the first to do it...


as it is too pricey for me at this time....
but that is the direction I want to go... oh and a new ratio for the rear end

 

I have a working 460LE that I would love to trade for a manual bellhousing.

 

I hate to say this but the knowledge of the six speed just using over drive may or may not be correct...


about 5 or 6 years ago I applied to be the boss where I am... they gave the position to a complete boob... in order to help him on his way... ( him and his son where always trying to come up with some wonder thing to patent so they would hit it BIG )
I walked into his office and drew on his white board the plans and concept of the Binary transmission.... you just need 3 planetary gears.... 000 neutral, 001 first,
010 second, 011 third, 100 fourth, 101 fifth, 110 sixth, and 111 seventh


so I am so glad his destructive disruptive self is no longer a part of my life....
yes I know that patent is worth MILLIONS....


and he most likely was too proud too have used it back then....
anyone ever watched the movie the water engine...
my point

 

This $950 controller and a GM 6L80 or 90 might be a good option.

Gear spread on 4l60 3.00 to 0.70
Gear spread on 6l80 4.00 to 0.67

 

The GM 6L80 is a BIG transmission and WILL not fit in the XJS transmission tunnel with out surgery. The 6L80 is about 2-3" deeper than a 4L60 I suspect you will need to cut a hole in the tunnel.

I have a 4L60e and I'm very happy with the conversion. It was almost a bolt in with adapter and TC spacers, I had to slot the TC holes in the flex plate as the 4L60 converter has smaller PCD than the TH400. I only need a FBH in one spot on the tunnel and I cut the ears off the 4L60e ( a 1994 1 piece case 4L60e). The TH400 shifter was a direct fit only needed to change the selector indicator panel for the 4th gear.

 

I would think the hardest part of adapting a newer transmission is going to be the electronics to control it. Adapter plates etc are relatively easy to do.

 

Yes true there would be some work but when were jags easy? First gear on the 6l80 is curca 4 to 1 vs 3 to 1 for the 4l60. Rumor has it that GM engineers say that lower gear equates to about a 7% gain in acceleration. So from a 13s 1/4 mile to a 12s 1/4 mile.

 

See my post above.

 

Whoops forgot the link...

TCM-2650 Mechatronic Controller Archives - Zero Gravity Performance

 

If you're up for the work I say go for it. Although I have drive a Commodore V8 with 6L80 and a Ford with ZF6HP, I would go with ZF6HP IMO it's a far better transmission than the GM unit and is already behind some pretty powerful cars.

 

I considered Gear Vendors before my manual conversion. Basically the unit bolts to the back of the TH400. The problem, in short, with the XJ-S is the driveshaft tunnel is to small in order to fit the unit.

 

What's the spacing of the other ratios? I wonder about the drop-off from 1st gear to second gear, and/or 2nd to 3rd.

I can envision a situation of screaming off the line in first gear and then falling flat afterwards...if the spacing puts the engine well below its power band.... forcing a long slog back up.

I've oft wondered the same about the 4L60 behind a 5.3 V12. First gear being 3.06 (on most versions) and 2nd gear falling off a cliff to 1.62

Thoughts and experiences?

Cheers
DD