Hi all!
Back again after many years off this forum and had to create a new account because I had forgotten username and login.
My name is Richard Johansson, I live in Sweden and my only Jaguar at the moment is an XJ-S 1987 with a 6 liter V12. The car is in a fairly good state but I don’t use it at the moment. The usual story with to many cars and the jag needed som work so it ended up in a corner of my garage with some old blankets over it and a thought of some day driving it again.
When it worked it was a fun car to drive with the bigger V12 and AJ6 Engineering manifolds, throttle bodies and a big bore exhaust system. The gearbox didn’t appreciate more power and a heavy right foot so it started slipping over 4000rpm and after a while I just parked it to gaver parts for a conversion to a manual gearbox.
Oh well, some day it will be ready for the road again.
Welcome back; sounds like a fantastic project. Have you considered a 4 speed automatic? Installing a 4L60/700R4 with torque converter lock up, along with the axle ratio change needed anyway, is another performance alternative (more in keeping with the car, in my opinion). Good luck!
I did consider an automatic but I bought a Getrag 265 manual gearbox with pedal assembly and drive shaft so that’s what I’m going to use. Unfortunately it was the gearbox without speedo drive so I have to figure out what to do there.
I have the 3.54:1 gears too but that has to wait because I don’t know if I really need them.
Richard, 3.54 rear end is much better with your 6.0 V12. What’s the ratio of 5th gear on your Getrag 265?
I have a TKO600 with a 0.68 5th gear which gives approximately 90mph @ 2,500rpm.
Andy.
See if you can find a differential from an ‘88 or ‘89 6 cylinder; diff mounted speed sensor and the 6 has the correct carrier for your 3.54 gears (if not already equipped).
There’s a video online of a guy with an XJ-S that simply attached a couple of magnets to the outside of the drive shaft and mounted a pickup near them. Dunno how accurate that made the speedo.
That’s basically what I did when I installed the Rover V8 in my MGB with the Lucas 14CUX fuel injection; it needs a speed sensor signal for idle to not drop out (uses an idle air control motor). I glued two cobalt magnets to the trans output flange and installed a reed switch fed B+ on one side, the other to the ECU ( needed a 12v square wave signal). Gives about 8000 pulses per mile, but turns to hash at freeway speeds. Works for what I needed, wouldn’t be good for a speedo. Maybe a Hall Effect sensor, such as ABS uses? Or a toothed wheel and the diff sensor used from ‘88 on…
If I’m not totally mistaken the fifth gear is 0.82:1 so with that 3.54:1 gear ratio it works out to about 120 km/h at 2500rpm. Good enough for me because fuel economy isn’t important to me.
Bad choice having a V12 if I wanted fuel economy. 