Thread: ZF8hp into td6?

Ok, I know the transmission has been tackled several times before...but hear me out.

I got the miss's a bmw 320d. they have the 8hp box, absolutely fantastic bit of kit. It got me thinking, this box has been designed to be "universal", apparently it runs entirely off Can bus with 4 wires in total, Power, earth, can-high, can -low.

this box, being universal, has been fitted into the 2010+ l322, its also been fitted to the E70 X5 (has N57 diesel). so. mechanically it can be done via a few mods to the bell housing (starter motor is in the wrong spot). The transfer case stepper motor would need to be controlled some how also as its would come from the later model rover also, but would also provide the much better torsen center diff. (arduino can easily control a stepper motor and switching signals from the existing l322 TCM)

Electrically...in my mind, chime in can bus experts (aka Gav if you're watching) is it possible to take the existing parameters the gear box needs from the existing TCM, put them all into an arduino powered CAN-Bus converter, and spit out a can signal into the 8hp? baud rates etc can be made to suit whatever is needed really. finding out what the trans requires would take a bit of research however...

thoughts?

you can also find a 8hp and transfer case to suit for a lot less than a 5l40e rebuild....

yes, that's what a "mechatronics" unit is - the valve block, with sensors and ECU in one unit. The idea is to eliminate several connectors and a loom - down side is most of them are not serviceable - faulty valve = $3000 for a new mechatronics & you can't get it going because it will not have any software on it when it comes out of the packet. Been through this with my wife's car.

The issue is data sharing with the engine, without the link it would work, but would be horrible. There is a lot going back and forth, for example, the trans requests throttle reduction for certain functions, with out this it will get rough. Several years ago when we talked about 6hp24 I did a list of all the comms for the 5L40 that you would ideally want.

Remember the TD6 doesn't have all the data on CAN either, there is a lot on the iBus and some more on the kBus. The instrument panel is the central hub for the 3 but there are several fields that aren't passed to CAN - whether we would need them I can't remember.

Other issue I raise (each time this comes up) is the current gear variable that is broadcast. We still don't know what the ABS or instrument ECU (just for example) will do when it receives a current gear = 6 signal.

Minor thing to consider for long term ownership - Once the new box is in there, how do you read faults. All of the service kits out there are looking for a particular ECU based on MY.

Originally Posted by chaybra

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Electrically...in my mind, chime in can bus experts (aka Gav if you're watching) is it possible to take the existing parameters the gear box needs from the existing TCM, put them all into an arduino powered CAN-Bus converter, and spit out a can signal into the 8hp?....

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My initial thought some years back was to leave the existing TCU and convert to the new transmission control unit, however the existing TCU will stop shifting once it gets to 5th. And without the analogue feed back on things like shaft speeds, fluid temps, TC lockup requests ect (which would be completely different) the existing TCU will quickly start throwing errors and be limping home before you get out the garage.
It would need a converter doing CAN-Bus to CAN-Bus translations, the old L322 runs what is now a very old CAN standard It would need to supply data the new trans needs (which is more than what the 5L40 receives) and just as important, it needs to feed all the crucial data back to the other systems (not just the packets the engine needs), this would also enable things like the current gear to be modified. Remove the TCU, plug the newly developed converter into the CAN-Bus then the converter communicates with the 8hp.

Data is broadcast by other ECUs for the trans TCU, not just the instrument cluster in our cars, the later cars more so as everything is on the CAN-Bus (there is no central hub between networks). This transfer from BMW to Jag systems was a gradual move which started in the MY05 cars (ICE was only system at first), each MY year more systems moved to the CAN resulting in a full CAN setup by MY08

That's where I got to (with the 6hp in mind) - Started writing a data spec and quickly lost interest once it was clear I would be on my own. 12 months later my 5L40 started to slip (as expected) - drove in to shop, paid $ for rebuild, enjoyed my weekends since....

As a software engineer, I will say anything is possible. However, at what point does your spend ($ and time) become more than just trading in on a newer car (what value do you put on a trans upgrade given the engine and other goodies that the new one will have). If a few of us get together than maybe it would be worth it, geography makes that a bit harder.