When the original 5.3 liter enigne in my XJ12 started to have internal machanical problems at 140k miles, I decided to pull the engine and build a 6 liter replacement. At the same time I also wanted to improve the performance of the car by swapping the 3-speed TH400 transmission for a manual transmission. Don't get me wrong the TH400 is a GREAT transmission. Incredilbly stong, and relaible, the transmission in my car provided very smooth shifts under normal operation. I also discovered that if I left the shifter in the '1' position while accelerating from a stop, it would produce the most incredible tire-smoking 1-2 shift at exactly redline. Nice!
What wasn't nice was that after the 1-2 shift, there was only one more gear left. With the 3.31 rear end, this meant freeway cruising @ 3500 rpm. I also had non-stop troubles with transmission leaks. First from the pan, then the kick-down switch, and eventually the torque converter decided to empty half its contents on my parents driveway. Not good.
So, the search for a suitable manual transmission began in earnest. The first step was research, research, research. From waht I doscovered, there are basically 5 common chioces for V12 transmission conversions. In no particular order they are:
| Transmission | Speeds | Torque Rating | Dry Weight | Shifter Position | Common Application |
|---|---|---|---|---|---|
| Borg-Warner T5 | 5 | 330 | 76 | 19" | Mustang '82-93 |
| Toyota R154 | 5 | 450 | 94 | 19.25" | Supra Turbo '87-'92 |
| Toyota W55/56/58 | 5 | 325 | 74 | 18 | Celica (RWD), Supra '83-'99 |
| Tremec 3550/TKO | 5 | 425 | 95 | 19" | Mustang aftermarket |
| Tremec T56 | 6 | 450 | 135 | ? | Camaro '93+ |
| Richmond ROD | 6 | 450 | 108 | 20.75 | Racing |
There are also a few other choices such as ZF and Getrag which I was not able to find much information on.
****More coming later. This page is still a work in progress****
1987 Toyota R154 transmission (Toyota Supra Turbo)
Weight 94 lbs (dry)
Transmission face to shifter center = 495mm
Input shaft length = 190mm
Similar transmissions:
R150F/R151F: Toyota Pickup 4x4 (V6 & I4 tubo), Toyota T100 & Tundra (V6)
AX15: Jeep Wrangler(?)
1994 XJ12 6 liter bellhousing bolt pattern
Nope, it's definitely NOT Chevy.
gary@garyandliz.com
Go back Home.