Hi all,

We were wondering about the possibility of putting a ZF 4HP24 gearbox from an X300 into a 1990 XJ40 4.0. Even though both cars take the same transmission, is placing a box from one into the other possible? If so, would there be any differences in fitment between the two, and what would they be?

Any advice would be greatly appreciated. Cheers.

 

Why not check the part numbers?

 

The main differences as follows.

The oil cooler pipes have a different connection type.

The electrical plug has a different pin arrangement/ 9 pins rather than 8.

The transmission mount interface at the rear is different.

so all in all, it’s not going to be easy to use on your application.

 

Yes, it turned out we needed the gearbox with the number 030042. The equivalent number on the X300 transmission was slightly different, and that one didn't end up fitting our car.

 

Thank you for the response. We had already bought the new box, so we tried installing it anyway but found all of those discrepancies and thus figured it wouldn't be possible.

So we got another box, one from the same model car. It seemed to install correctly, only that when we tested it, we experienced the same issue that we had with the old transmission where the reverse gear would engage whilst the drive gear would not. Upon diagnosis of the issue with the original gearbox, we were told by the mechanic that we were best off fitting another transmission. So we are not sure what the problem is here. Is it some issue that is external to the transmission? If anyone has any ideas, feel free to let us know.

 

Sounds like a selector issue rather than the transmission?

Larry

 

Well those were rather large parts to throw at the car!! That must have been very frustrating. This is an odd problem.

No offense intended, mechanics often mis-diagnose and even though it is unintentional, it is usually based on their best understanding. Which isn't always the best for an old Jaguar.

At this point you probably need to dig into the shifter assembly. It is quite intricate looking but I understand the 4HP24 is 100% mechanically/hydraulically operated which at least minimizes electrical complexity.