I been wondering for a while. I've heard of numerous posts about the failure of the ZF5hp transmission found in the XJ8. Yet, for the XJR, havent heard too much trouble with that box.

Now I wonder this. If the 4.0 regular and 4.0 SC is basically the same engine, I assume, the connection point for the Transmission bellhousing is the same. (correct me if I'm wrong.). So if something was to happen to the ZF, which many say is crap for the amount of power the regular XJ8 puts out, making it basically unsuitbale for the near 400 the SC puts out, what is stopping an owner from dropping the 722.6 5G-Tronic tranny in a naturally aspired 4.0 and calling it a day? I guess one of the biggest hurdle would be software.

Note: Owned many cars with ZF trannies and each always had a legion that said they were crappy gearboxes. Ironicaly, never had any problem with ZFs. And very familiar with the MBZ boxes. Complicated buggers but sturdy as hell, usually.

 

main problem is the fact the gearbox 'talks' to the engine control module and body control module and speedo cluster. You would need all for even the remotest chance of it all to work.

 

Body control module..? Does that mean that the gearbox is connected to CATS? Or does it just use the same sensors?

 

If you think about it, the BCM is on the CAN network between engine/gearbox, how else would the car know which gear it was in, and to light up the selector. Furthermore, the instrument pack also requires a signal from BCM, it's not connected directly to the gearbox module, or engine module. The BCM on each car does a lot more than you think.

Once you've grasped how CAN networks and the interlinking modules work for both cars, then you can understand how difficult it is. This is without considering the pin outs on each module being different including the harnesses/looms, it's not just a case of slinging in a different gearbox.

I've looked into this in some depth. If anyone has a working conversion, I'M ALL EARS!

 

Oh, ok. Misunderstood what a body control module is

 

You might need something like a "translator module" to go in between the BCM and the transmission. People still put different engines and transmissions in custom cars, so it must be possible to do. But no doubt expensive.

 

makes sense.

 

A very interesting idea. But if you're handy with wrenches, you can repair your ZF for a lot less work and money than putting in a different trans.

 

On tccoa, there was a discussion about swapping the newer Ford 6r80 into a Thunderbird. It will fit, but all data is transferred over the CAN network of the newer vehicles. Surely, someone out there understands the systems, CAN operation and integrated circuits. Like I said in the thread over there, "I wish someone would just make a module that can handle the data and have speedometer outputs/etc to make this happen. On the jag it would just need to be a "translator" as you say, with much less wires. All we need is the know-how. FWIW though, my ZF hasnt gave me a problem since I upgraded the clutch drum.

 

Oh no, my tranny is just fine and if something was to happen I probably would just rebuild it myself like I did another ZF not too long ago.

Unfortunately, not everyone seemed as lucky to have problem free ZF tranny as I have. I just was wondering if these trannys go out like that why no one bothered to put in the 722 tranny, which there is less reported problem on the xjr (and MBZ e55). Now I understand from the responses why not many people bothered to do it. At the same time as another response, it probably is possible but might be exspensive, but swaps always are. People put v-12s and 99 s-class motors into W126s every so often even though the software is no where near compatible and cost a pretty penny (or thousands of pretty pennies).

I'm not sure if my tranny has the upgraded drum but as long as it's working I'm good. only turned over 50K so far but I'm not too keen on the "lifetime" fluid mania. What monkey came up with that idea? Use basically same fluid, take away dipstick and that magically makes it lifetime when a few years ago it was in bold red letters to change the fluid every so often. Guess they figured buyers of this caliber cars in 1998 and up would only keep the car till warrenty expires and buy new one. Guess they didnt realize that some of us like the car more than a piece of dispoable toilet paper that is used to impress people for a few years.