Hello all, apologies if this has already been covered but ive just bought a 52 plate 2ltr tdci 5 speed Mondeo engine code FMBA. Does anyone know what 6 speed box would fit? Ive got to do the DMF at somepoint so thought I would change the box at the same time. I know I would need to change the stick and linkage as well. Thanks Pete

Well I've never done this job but I would have thought it was a lot of work. For a start you don't have to take the gearbox right out to change the clutch and dmf (just drop the subframe one side). As you say the lever and cables would need to be changed. A new clutch hydraulic line would also be needed. I have no idea if the driveshafts would fit ok Personally I wouldn' tbother. It'd probably end up cheaper to sell the car and buy a six-speed!

This was a conversion i had considered do-ing but i did not do because -

The MTX75 5-speed is tougher and stronger, longer lasting than the MMT6 6-speed box, the MMT6 is "soft" - it has plastic parts in it is more liable to fail over time than the MTX75 - 5-speed

Although the swap is a "drop in" the pick-up point for the speedo is different on some models, so you mak have extra work/ hassles to get the spedo working

The DMF/CSCclutch/ is more expensive to replace on the MTX75 - 5 speed than the MMT6 6-speed - i bought a solid flywheel conversion (SMF or single mass flywheel) carbon fiber/kevlar clutch, heavy-duty pressure plate with 33% strronger clamping force, and genuine Ford CSC (concentric slave cylinder) - this was around £100 cheaper than for the 6-speed, and cheaper than the stock DMF (and better)

Having the extra gear is not nessisarily better - you may have relaxed crousing on the motorway on the flat and downhill, (with good MPG) but you may have to change down every time you get to a hill (or a steep hill - depends how much power and torque you have) - the 5-speed may be better for b-roads in traffic etc and may have a better MPG at some speeds - if you dont do a lot of motorway driving, you may be better with the 5-speed

Finally - the top geart acceleration of the 5-speed is much quicker than the 6-speed the 6-speed is an overdrive and to make decent progress you may have to change down (even on the motorway)

Just for you (borrowed from another post) here are some top gear 50-70mph acceleration times, on the top of the list with the quickest time is my modified mondeo 2.0L mk3 deisel, with the MTX75 5- speed box - the top gear ratio is muh lower than the top in he 6-speed, and althogh it can accelerate from 50-70mph in top in 5-seconds it can still reach 130- 140mph (on the autobhan, of course!) on the bottom of this list is the 2.2 litre ST-TDCI with its 6-speed box - it takes 11.5 seconds to accelerate from 50-70mph in 6th (top gear) in 5th it takes 6 seconds (almost half the time) - with the 5 -speed box i can accelerate from most speeds without having to change down (ok so there is a bit of work done on the car, but the top gear ratio is a significant factor)- the list includes sports cars/ supercars etc -

stats/ evidence -

>My mondero td est. 5.9 secs /4.98 secs in 4th (old) - new 5.0secs in top (5th) 4.3secs in 4th (on speedo) speed geared for 130/140mph approx 1400kgs)< figures at time of testing - vehcle has changed (eg lighter/ more power)

Focus ST3 - 6.1 / 5.1 in 6th/ 5th (6-spd) 247bhp 340Nm 154mph 1362kgs

Lambo Gallardo 6.2 sec

Focus RS 6.3 sec (6th)

Ferrari F430 6.4 sec (4.3L v8 490hp343lb ft 196mph/0-60- 4sec /0-100- 9.2sec 1450kgs)

Testarossa 7.4 sec (in 5th / 5 speed box)

Ford GT 7.4 sec

911 Turbo S 7.8 sec

Fiesta ST2 7.9 sec 6th / 6.0 in 5th

BMW330D 8.4/5.7/4.7/3.7 8th/7th/6th/5th 8sp auto 3.0L luxury touring 255hp 560Nm 0-60mph 5.8secs

Porche Boxter 2.7 8.5 sec

Civic type R 8.9 sec

Mondeo ST220 9.1 sec in 5th? - 5sp version (151mph) 0-60-6.8/7.4secs 0-100mph 20.8secs/18secs)

Impreza WRX 9.5 sec

Sierra cosworth Rs500 10.1 sec

Mondeo ST-TDCI 11.6 sec (in 6th) 6.5 (in 5th)

Having the extra gear is not nessisarily better - you may have relaxed crousing on the motorway on the flat and downhill, (with good MPG) but you may have to change down every time you get to a hill (or a steep hill - depends how much power and torque you have) - the 5-speed may be better for b-roads in traffic etc and may have a better MPG at some speeds - if you dont do a lot of motorway driving, you may be better with the 5-speed

Finally - the top geart acceleration of the 5-speed is much quicker than the 6-speed the 6-speed is an overdrive and to make decent progress you may have to change down (even on the motorway)

Having a mk IV Tdci 140, I can add

• yes, the 6th gear is a bit tall
• for me, 58 is the lowest I can go, even on the lightest of accelerator settings, before the engine gets a bit grumbly...so even on a M'way a 60 mph contraflow or slowdown is taken in 5th not 6th
• the car is (slightly) quieter in 6th at 70 mph than 5th; not a big thing, bit it is there
• there might be a small fuel consumption advantage, but if it is there, it is sufficiently small that you'd have to measure very carefully to find it
• At 70 mph, you can happily take slight inclines in 6th, but it is certainly the case that you don't have to lose much speed at all before you have to change down at any incline (and anything more like a hill than an incline is going to be 5th) - it isn't bad enough to be a total pain, but having the 6th with this gearing isn't much of an advantage, either
• (probably) somewhere like Germany, on a de-restricted Autobahn, this gearing does make sense, here I am less sure

Note that you could also drop the final drive a little to make UK motorway speeds a bit more of an obvious choice for 6th. But then, what the advantages over a 5 speed with similar overall gearing is unclear (more gearchanges? is that a big advantage?).

Thanks for your knowledge guys. Think I shall run it as it is then :) I just wondered if it was worth it but I guess I can now spend my money on other bits for it :) Cheers