Hi all,

Has anyone thought about or even tried upgrading the tranny in 6HP26 XKR (4.2) from a ZF 6HP26 to a 6HP28?

The 6HP28 is the second generation version of the 26, with several improvements, including smoother/faster shifting, better power efficiency, the torque converter locks up much quicker, and it also has 100nm more max torque limit, (which would bring me a lot more peace of mind if/when I also fit Avos's twin screw SC upgrade).

Does anyone happen to know if a 6HP28 would be drop-in replaceable or not? (i.e same physical dimensions, and any software or other compatibility issues that would make it just not possible?)

Thanks,
Neil

 

Physically pretty similar. I'd guess, but the software is the big problem. The Transmission Control Module is a very important component in the XK's electronics, constantly exchanging data with the ECM, the Active Dynamics system, etc., and the 6HP28's TCM will not have the correct software to work with the modules in the 4.2 - they probably won't even recognise it. And no-one seems to be able to reprogram the TCM.

 

Physically it would fit but as Ngarara said, the software is the rub.

With the latest software the 6HP26 isn't too bad. The torque rating is typical German conservatism and isn't a problem for a Twin Screw.

The 6HP family is also the base for the Ford 6R80 so there are better clutches and shafts that will drop right in.