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Mister5Master

Gearbox swap from Mk3 to Mk2 1.6 TDCi?

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Hello everyone,

I want to ask if such a gearbox swap would be possible, or, what modifications to the gearbox to make to fit it in my car. The problem is that I feel there's not enough gears-going 140km/h (sorry for SI units, I'm from Poland so forgive me the metric system and my english) is just super loud on the highway- RPM is around 3000 on 5th gear and the car still accelerates decently, so it would make sense if there was a 6th gear. (i have the 109HP 1.6 TDCi engine) I started to think of a solution to this problem, and after some research I came to a conclusion that a gearbox from focus 3 1.6TDCi 115HP would be perfect for my car. The thing is I have no idea if it's as easy as just taking off the old one and putting the new one in it's place, or there is some mumbo-jumbo going on with the gear selectors, clutch equipment etc. The only thing I know is that the mounting openings on the bell mount are the same. If those transmissions are interchangeable in a plug and play way, then I guess it's worth trying, because the gearbox from focus mk3 costs around 1000-1500PLN here (used one, to get the price in pounds just divide by 5, so 200-300GBP) Plus some cash to the mechanic or a bottle of good vodka for my friend to let me use his garrage for a day or two. If so, I'm considering actually doing it, but i have to be 100% sure it will fit without any additional work. And if it's not that easy to pull off, is there any alternative solution? Like for example buying an used 5 speed transmission from focus mk2 and swapping just the gears from 5th gear (i saw a gearbox like that for 60PLN, so basically the cost of a good coffee in the UK i suppose). But I don't know where to get the gears from, and how expensive would they be. Or maybe swapping the main differential gear for a one with fewer teeth in order to decrease the reduction on all of the gears?
I'm grateful for any answer, please let me know what you think and once more, sorry for any mistakes I made, I'm not a native english speaker and also my keyboard is malfunctioning. Thanks!

Grzegorz

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The Focus MK3 1.6 TDCI has the 6-Speed Ford (Getrag) B6 gearbox. This type of gearbox has never been used on the Focus MK2/MK2.5. 

The B6 gearbox will not fit to your car without several modifications. For example:

* Driveshafts will not fit and need to be custom made in the correct length and spline pattern.
* Gearbox mount will not fit. A Focus MK3 mount may fit but in worst case scenario the mounting bracket needs to be custom made.
* The shifter mechanism will not fit. The mechanism of a different MK2/MK2.5 6-Speed gearbox may fit as long as it has the same gear number pattern.
* The clutch is different and needs to be changed

Apart from this the flywheel may also be different. The Focus MK3 has the newer 8-Valve version of the 1.6 TDCI while the Focus MK2/MK2.5 has the old 16-Valve version. There are many differences between these engines. 


If the car has Cruise Control this will also be a point of concern. After changing the number of gears / gear ratio the Cruise Control will no longer work. The engine speed / vehicle speed ratio will no longer match with the values that the PCM expects. As a result of this the Cruise Control will be disabled.

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11 hours ago, Mister5Master said:

sorry for any mistakes I made, I'm not a native english speaker

Your English is excellent and your spelling and grammar are a great deal better than many of the natives on this forum! 👍👍

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So you're sayig that swapping the gearbox would require serious reprogramming of the ECU to compensate for the different gear ratios (in order for cruise control to work)? I didn't hnow that. Also, by the driveshafts you mean the ones connecting the gearbox (differential mechanism) to the wheels or the drive shaft in the gearbox itself (the shaft directly connected to the engine through the clutch)? Supposing I bought 2 gearboxes-the old 5 speed one and the 6 speed one from focus mk3 + a shifter from 6 speed focus mk2 2.0TDCi would that be possible to "merge" the two together (the old one's casing with the gears and shafts from the new one)? That would solve the mounting points problem, the shifter problem and possibly the driveshafts length and mounts wouldn't change? So the one thing remaining would be altering the PCM's software in order to compensate for different gear ratios and changing the clutch for a one that would fit the transmission's input shaft. If that worked it wouldn't raise the cost of such a modification significantly and would be a bit reasonable. But in order for this idea to work it would require that the shafts from both gearboxes have the same length and diameter and I don't know if it's true. But that sound like a lot of work to do, and given that this vehicle is my daily car I doubt it makes sense to swap the transmission in the near future. But If I manage to get a successful attempt of such a swap I'll share it here with a to-do list + cost for people willing to replicate this. But that will be probably in a few years if I manage to make some money and buy a new car in order to attempt such a project.
By the way, are there any other ways of decreasing the RPM of the engine while maintaining given road speed other than hacking the gearbox? I realize that changing the wheels for bigger ones would make a small difference, but it would require an upgrade from 15" to at least 18, and that would probably be illegal in Poland because such wheels weren't offered with that model, plus the tyre would be really thin and I mostly drive my car through the city, so that's not ideal. Also I really don't like the looks of oversized wheels on a car, i guess the limit for a focus would be 16", in extreme cases 17".
Thanks for the reply, I really appreciate the effort.

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