Good morning,

Looking at the xkr-s with a 6-speed, I was thinking about what would it be like with an updated gearbox, say the 8-speed (zf8hp) units. Has anyone tried it? For the technologically savvy, how hard would it be to reprogram the ecu/tcu to work? Would it be better to try to go manual transmission?

Just posting up a question for discussion.

v/r,
J. Martinez

 

As we all know with money and time almost anything can be done. My guess is with any change of the gearbox there would be complication with the programming of the sub-support computer systems. So the work here is understanding the integration of the 6 sp and then how to make the 8 sp work the same either by reprogramming or by making the 8 sp look like a 6 sp. As far as the manual is concerned I was led to believe that a Jaguar specialist in Ma. called Donovan Motorcar Service is working on this modification. I talked with them last Sept and they said they were being asked by a customer to do the conversion. I don't know the progress. As another thought that being the 6 sp from the 2007-2009 cars are different then the 2010-2015 so I suspect there needs to be some mods to do that conversion. Hopefully we'll see something in the future.

 

If you were an electrical engineer with Jaguar with a fist full of cash, no need for the car to ever run again and still remembered the code format for the older car, sure try it. Otherwise, either find an 8 speed version or forgetaboutit... Same answer for the manual conversion since the ECU limits the engine output to what the trans will allow. (let that last bit sink in for a moment).

 

Ranch I'm just the messenger here. One of the engineers I talked to from Donovan said they were looking at it and understood some of the issues but were looking for some work arounds or simulators to fool the ECM . They said it wouldn't be easy but were looking at it.

 

There are two big differences between the 6 speed and the 8. The most obvious is 2 more gears, but in reality (I have the 8 speed in my f type) that is the least important. What is more important IMO is the speed of the changes (much faster than the XK). I'd have thought you could fix that with an autoflash.

I tried one on my daughter's MiTo DCT which had absolutely dreadful changes, it sharpened them up beautifully.

I dont know how it would work with the Jag, but here is the link. TMC were great to deal with, and the flash was super easy to do. You have to redo it when it is tuned, but it is pretty easy. Dont know how it would affect warranty https://www.tmcmotorsport.com/autofl...gearbox-tuning

 

The XFR-S received the 8 speed transmission but the XKR and XKR-S didn't because of packaging restrictions, I believe. The 8 speed is a little bit larger and thus does not fit our chassis' transmission tunnel. Programming and such would be tricky, but probably nothing more than using an XFR-S' ECU and TCM to make them talk.

It's the fitment itself that wouldn't work, to my knowledge.

 

I just sent them an email asking if their gearbox tuner would affect or erase any aftermarket engine tune previously loaded in the car. I'll report back with their response and if, after doing some more reading, I like what I see, I'll bite the bullet.

 

I don't see it as a feasible project.

The changeover to 8-speed in other models coincided with the change from Denso to Bosch for the engine ECU (PCM).

The XJ and XF with 6-speed had Denso PCM's, same as the XK/XKR. The 8-speeds got Bosch PCM's.

The XK/XKR kept the Denso PCM right to the end of production, as well as keeping the 6-speed.

The software in the Denso and Bosch PCM's is totally different. The PCM and the TCM work together as a pair to control the transmission. An 8-speed TCM is not going to work with a Denso PCM.

I have been told that there were a few bastärd XJ and XF at the crossover point when the PCM and transmission changes were made (i.e. Denso PCM with 8-speed, Bosch PCM with 6-speed), but my experience with the 2012 XF tells me this is a massive headache in regards to programming and you could waste your life trying to solve it.

Furthermore, the instrument cluster in the XK does not support 8-speed (gear and shift indication) and you can be sure that the gearshift module won't either.

Lastly the diff ratio in the 5.0L 8-speed cars is not the same as the 5.0L 6-speed, so that's another spanner in the works. XKR has 3.31, F-Type 5.0L has 2.56, for example.

This project finds itself in not just the Too Hard Basket, but in the Way Too Hard Basket.

 

I would stay right away from any magic dongle that supposedly reprograms the TCM in these cars.

I've come across some very bad reports regarding Transmission tunes

See here http://www.jfautomotive.co.uk/ecu-re...earbox-tuning/

The unit that connects to the OBD port, the white box.

You see the same white box here GolfGTIforum.co.uk - An independent forum for Volkswagen Golf GTI enthusiasts.

Along with a description of what it does (or doesn't do) plus a lot of dirty laundry comes out about the guy behind the device, it doesn't paint a good picture at all.

These boxes come in different colours, and different housings, but they are all the same inside.

Knowing how a reflash of the ZF TCM works using the dealers diagnostic tool, and the way that the SCT tuning tool works on Fords with ZF licensed transmissions, there is NO WAY a little dongle like these can do a proper reflash or "tune".

"All this box does is load a canbus or signal blocker onto your car which then prevents the gearbox ecu communicating with the engine ecu. In layman's terms it allows the gearbox to do exactly as it wants without any safe working limits! So the gearbox will match the full torque limit of the engine giving the impression that the gearbox has been remapped, which it hasn't. So if the car is remapped then the gearbox will just match the torque output"

Proper snake oil. Steer clear!

 

My oldest son bought a '14 Cherokee with a 9 speed trans. Kind of gimmicky and it doesn't shift into 9th until almost 70 mph. Read on your link about the trans shifting firmer / faster with a fresh reboot and noted that mine does run harder and shifter quicker after a reboot. Finally one good thing from the ICarsoft LR2.

 

The only manual XKRs I'm aware of (there may be others) are the 4.2 GT3 race cars from 2008/9. But they have custom ECUs and a Hewland transaxle 'box, and they don't have to integrate into a normal car's systems. So, they have an XKR shell and engine, but they're not really an XKR as we know it.

 

Cambo, thanks for that. You saved me a bit of time doing my own research.