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Td5 auto box in a Td5 Defender how?


GBMUD
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I have been thinking about this again, having asked a couple of years ago and received a lot of valuable advice about Mega-Shift. I understand and accept that Mega-Shift is a good solution and offers many advantages, but it appears complicated and I lack confidence, especially if there may be a simpler - if less elegant and versatile - solution.

I did not really get much feedback about the possibility of using the existing Discovery electronic gearbox control hardware in the Defender application. Has anyone done it? Does anyone know that it will or will not work, and why? Does anyone even know what bit make the whole thing work!? I am thinking specifically about Td5 Defender gearboxes rather than P38 please, as that is what I will be working with.

Thanks for your ideas...

Cheers

Chris

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Hi,

You have 2 ways to do this :

1) as mentioned above you can put a td5 bellhousing and converter on a 300 tdi disco Autobox

2) fit the disco td5 Autobox and control it with a 'Compushift ', see our website for details

Both options have their pros and cons :

The tdi Autobox is cheaper but you have little control over the Autobox shift pattern and converter lockup, you will also have to make a linkage to pull the kickdown cable

The Compushift will up the cost of the conversion but you will have total control over the Autobox to adjust shift speeds, shift pressures and converter lockup speed as well as tiptronic control etc if required,

That's the bottom line, if you are on a budget put in the tdi box and it will work ok as an auto but maybe not with a perfect shift pattern or if you want it to drive better and don't mind spending a bit more then look at the Compushift

Dave

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Thanks for the ideas. I want the Td5 autobox and not a Tdi box with a Td5 bellhousing, I just do. I do not want to spend the thick end of £1000 on a control solution, as great as it is - thanks Dave.

Something in a Disco2 controls the gearbox, I thought there was a gearbox ECU, but perhaps it is part of the BECM and not a separate unit. Can anyone clear that up at least?

Cheers

Chris

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Even if I had to connect a D2 BECM to the gearbox controller, (or run a combined BECM/gearbox controller) what essential connections would the BECM be looking for, and could I spoof them?

I have just found a D2 wiring diagram that suggests that there is a separate controller, and a connection to the BECM for the dashboard gear position indication and one or two more items, though I am not yet sure what they may be.

It did occur to me that I heard somewhere that a D2 speedo transducer gives a faster signal than the Defender one, I suppose that this might upset the gearbox control...

Cheers

Chris

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The v8 disco 2's have a seperate gearbox Ecu so I'm assuming the td5's do. Trouble is, it's going to need inputs from engine Ecu and probably abs Ecu so unless you can get these inputs to work it probably won't shift. Those inputs may well not come direct from the different ecu'a either they might go via the bcm.

Maybe try getting wiring diagrams and studying how it is connected? Or buy a disco and find the Ecu and remove wires from the trans Ecu and see if it still shifts?

I've recently bought Compushift from Dave for running a p38 box in my winch challenge buggy and its a very smart looking setup (not fully fitted yet) it's a lot of money but for a near enough plug and play situation it's not bad value,

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Humm, now you got me wondering myself, checked AT site, and there is an electronic version, the 4HP22EH

Either way, Megashift can drive 24 or 22, the only thing you need is the solenoid pattern for the gears, and you set this up in the box config. Normally there are two solenoid on 4-speed boxes that control the gears, therefore a combination of on and off on these gives you the gear you want. Then..... you have two further types of electronic boxes, one with a third solenoid, which controls the box pressure, or one with a kickdown cable, which controls the box pressure, this is the simpler one to MS, as you need to drive the third solenoid with a PWM signal rather than just on/off, perfectly doable, but you will spend a little more time perfecting the map. The pressure here determines shift ferocity, btu if set too loose, you will slip the bands and burn the box out, too tight and you will shock load stuff more than you probably wish to...

Here's the data for a ZF4HP22EH: https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CDgQFjAC&url=http%3A%2F%2Fwww.not2fast.com%2Fmegashift%2Ftrans_data%2FZF_4HP22-24.xls&ei=eAwUVcrPLqzW7AaxqYCYCw&usg=AFQjCNGoKepP0dDVl_yoyXU4y4B4z_8oEQ&sig2=94ivQoue29BJ5QQr1JW4dw&bvm=bv.89217033,d.ZGU&cad=rja

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Looking at the inputs the gearbox ECU wants, everything but the CAN lines seem to be related to the gearbox itself.

I wonder how different the Td5 ECUs are between the Discovery and the Defender. I can't find anything about the Defender ECU's pinout in the RAVE for some reason.

If you need to transplant the Disco's ECM, it'll be a bit more difficult, because it'll have links to the BCU for immobilisation and such. Also putting in the BCU should be possible I guess, again a little bit harder.

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As you know I've played around with this type of thing a bit.

MegaShift is a good option - and will control pretty much anything. The down side is you have to build the board from individual components etc. It took me several hours to solder it together.

Then you have to configure it and design your own change maps + interface to the shift lever. All perfectly doable, but it requires a fair bit of investigation / effort / technical ability and there is far less help available than MegaSquirt.

Personally, I would be confident I could get the box working with the Disco ECU + BECM, fooling it to think it's in a Disco not a Defender. But I suspect this would take weeks of trial & error. Once you have it working, you still have no control of the change map and the default may not suite the dynamics of a Defender as well as a Disco (or it's intended use).

Personally, I think I would just buy the Compushift. At least you have support & backup. It's supplied with the correct loom to just plug it in and Ashcroft amongst others can tell you how to configure it to get it running with an initial change map. You can then tweak this to suit your needs.

Although the £1000 seems a lot, I think it represents pretty good value compared to the time even I would have to spend getting something working.

Having built my own gear controller for the Suzuki box and written my own control software - I think if I were going to convert my Td5 I would just buy Compushift and have something I could drive rather than another electronics project!

Si

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I'd agree with Compushift being the answer, I've used it both on my 4L80E box on the back of an LSx and an HP24 box on the back of a TD5. The 4L80E has been fitted since 2007 and the Compushift has proved to be very robust considering the abuse the vehicle has had in that time as a challenge and trials competition motor.

I do have the intention, time allowing, to try setting up MegaShift for the HP24 at some point as I've built my own and other peoples MegaSquirt ECUs since around 2002 and the MegaShift is a much simpler build. The downside with MegaShift is that, by comparison with both Compushift and MegaSquirt, there isn't the depth of knowledge available so you have to do a LOT of the work yourself when it comes to setting it all up - that is gradually improving though.

MegaShift is the cheap option where you will pay in time rather than money, Compushift is expensive for what it is BUT you get an option that pretty much works out of the box.

Either way I would not run an Auto gearbox on a Defender, especially off the back of a TD5, that I couldn't change the shift patterns on. Auto boxes will work OK with a "standard" shift pattern but changed wheel sizes, transfer box ratios etc... all can make the shift pattern clunky and degrade the driving experience. There's nothing more annoying than a box that won't cruise properly because it's constantly shifting gears, particularly where the vehicle is higher geared than the original use (Defender is nearly always higher geared than a Disco due to tyre sizes, more so when "upgraded" to a 1.2 transfer box).

Hydraulic boxes will work OK but you'll never get the best driving experience with them unless it's been valved for your vehicle and driving style and I suspect that would cost far more than a Compushift !

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