Jaguar 420G gearbox issues

[GALAXIECAMMER427]

Hi all, I'm a new member. I'm hoping someone out there might be able to help me out. I have a '68 Jaguar 420G it has a Borg Warner Model 8 3 speed auto box. It will not go into third gear no matter what I do with the throttle. I have had the gear box rebuilt with new clutches, valve body, and pump. The gearbox place has now had the car for nearly 6 months, They can't seem to be able to get it sorted. al the external linkages have been adjusted and set up. As the gearbox has been rebuilt( I know it has, because I saw it on the bench with the new clutches installed) I'm now thinking that the problem is outside of the actual gearbox. This is not a vacuum operated box. it works solely on throttle position, and kickdown. Please someone help me out, I have definately lost the love for this car.

[GALAXIECAMMER427]

Hi Thanks for getting back to me so quickly. I have the proper Jaguar Manual, which gives a quite detailed list of problems and solutions, also oil pressures in at various stages of gearbox operation. The gearbox people that have the car, have been all through this, and still no joy. I would go with you that it sounds like something outside the gearbox, but all adjust have been checked and double checked Throttle linkage and Kickdown cable. Thanks anyway.

[GALAXIECAMMER427]

Hi andy, thanks for the info. any idea where this switch is locted, the reason I ask there was a black push pull switch mounted on the RHS lower parcel shelf under the dash, like a muppet, I didnt know what it was for, checked to see if any voltage was present, which it wasn't, and disconnected the bloody thing, Although I cant see any reference to this switch in the wiring diagram, with regards to the solenoids, any idea where they are located. Thanks guys, it could well be you've got something there, like I said it would definitely point to something outside the gear box.Haveing been a Yank man up 'till now, not having owned any British Classics, I'm at a bit of a loss. These 420G's are a cow to work on, give me a good old yank any day!!!

[GALAXIECAMMER427]

Thank Andy really appreciate it.

[GALAXIECAMMER427]

Thanks very much for the info. When I was under the car at the gearbox place, I couldn't see anything going into the gearbox. With wires on it.
As you say I would like to think the gearbox guys would have checked this. I have the Jaguar parts catalogue fo the 420g.and there in ferernce to a speed hold solenoid. In the link you sent(thanks) it does state mk 10 3.8, maybe this was not fitted to 4.2 cars/420G's

[GALAXIECAMMER427]

Thanks ever so much Andy. I really appreciate your time on this, if I ever get the thing back working correctly I might well fall in love with it again. I've also got a series 1 4.2 xj with a manual overdrive, which is a much nicer car to drive. You are right, the mk 10's and 420G's were lovely old buses. Not many left now.