Thread: TD6 Manual Gearbox Conversion... Is it possible???

Long post here - please forgive that, but there is a lot of info in my head I need to get out.

So, been doing a lot of thinking while the transmission is being rebuilt, installed, removed, sent back for work, reinstalled... I don't really want to talk about all that, it is too depressing...

But, after it is all sorted, I figure that sooner or later, I will be doing this exersize again at some stage. I have no condfidence that the GM box, no matter how well it is rebuilt, or with what parts, will last as long as I currently plan to keep the vehicle.

With that in mind, I am pondering my options for when that time comes. I recon I have a few options, but some appeal more than others.

1 - Get the GM box built again. I think it is a no brainer that I don't want to go down this path again. Also, these boxes have a finite amount of times they can be worked on, as the pump housing is cast into the main housing, and requires machining once it is stuffed, you can only rebuild then 2 or 3 times before they are completly U/S. Remanufacturers of these boxes are already running out of suitable core to do this.

2 - Work out if the ZF box could be fitted - there is a bit of chatter around on this, and while I have no definate answer, it seems like the hardest bit could be intergrating the electronics, but still may be an option.

3 - Convert it to a manal transmission... Now, I know some will think this is impossible, or at least cost prohibitive, but I've done a bit of research, and I think it may be possible, and at a similar price to getting an auto done - assuming I do all the work myself...

I have gone through what I think I would need to do this, and I have a few blanks which I am hoping someone may be able to help with, or at least add to the discussion - remember, this is just a feasibility study at the moment. Starting from the engine, I have had these thoughts...

For a start, the BMW X5 E53 (2002) 3.0 TD6 model was available as a 5 speed manual out of the factory. I can't find a lot of info on these boxes, but it does beg the question - would it bolt up... Is the block the same on the manual and auto, and is this the same as the RR variant?

If going down that road is a bust, then converting to an entirely different box may be an option. 1st and formost in my mind would be - which box? This is a question I have yet to answer, but I have thought through a few other things.

Bellhousing - can get custom units made easily enough if the correct data can be obtained for the engine and gearbox. Cost would be in the order of $1,500 to $2,000... Another option would be to convert a bellhousing that fits the engine already, but this gets us back to the BMW box, and if one of those isn't available, then I doubt a bellhousing would be...

Spigot bearing - I don't know if the crank will have a recess for a spigot bearing, but as there was a manual gearbox option - maybe. Even if it doesn't, I can soon whip the crank out of the engine and get this machined.

Flywheel/ring gear - fairly straight forward if the bellhousing issue is overcome. You could get a custom one made, or modify an existing unit.

Starter motor - see bellhousing - that's all part af getting around that problem...

Clutch pedal - again, I don't think this would be a huge issue. There are plenty of aftermarket pedal boxes available, but I haven't checked out how much room there is to put this where it needs to go.

Transfer case - gearbox would need a custom output shaft and adaptor made to bolt up to the transfer case - while not a DIY job, there are engineering mobs that will do this. I wouldn't be the first person to modify a box to bolt up to a 4WD transfer case.

After all that, there would be the jobs of making an appropriate hole in the floor, and cosmetics of having a gear stick poking up through the console, but that is minor stuff compared to everything else.

The biggest hurdle, as with the ZF conversion, could be the electronics... Not sure how the car would react to not having an automatic transmission anymore... When the trannie crapped itself, the engine continued to run fine, and rev no problems - seeming oblivious to the fact the trannie was in a thousand bits, so not sure if just leaving the loom off, or pulling out the trannie ECU would work or not....

Anyway, that's about enough for one post. Feel free to add ideas, suggestions or any other comments - both good and bad - I'm a big boy, and I can take it.

This is not the first time I have gone and done something like this, so apart from the custom bits I might need making or modifying - if there is something that will work, and will fit between where the engine and transfer case is, I'll probably have a crack at it one day - this is a longer term plan, and someone else may have done this, or are planning this - who knows?

Cheers - Gav.

Some interesting ideas here Gavin. But what happened to your super duper rebuild 5L40E. From what you said they were the experts & I was going to use them when & if I ever needed to

Gary