View Full Version : T25 diesel gearboxes

21-03-2008, 06:49 PM
I have just become the proud owner of a 1989, 1.7diesel transporter. It has been fitted with a 5 speed box which turns out to be from a petrol model.....hence 55mph flat out!!!!!! Can anyone tell me if it is possible to change just the diff and if so can it come from the early 80's passat. Or what is the box code for the one with the highest diff ratio. Any info much appreciated as I am in the wilds of southern France:aargh4: and my language skills don't extend to high tech discussions on gearboxes. Thanls in advance STEVE.

04-04-2008, 09:16 PM
ok im Semi new to T25`s as I have a bay and am sticking a T25 Diesel in it, basically with T2/T25 gearbox the bell housing removes from the gearbox, as basically when sticking the diesel in the bay you can just use a T25 bell housing on the stock bay gearbox.

The same would be true of the rest of the T25 range, where I have noticed one difference is the gearchange, so the question is did your T25 start life as a petrol and be converted to diesel or has someone fitted the box from something else?

are you positively getting all 5 gears? I really cant see that 55mph flat out can be all 5 gears, sounds more like 4th!I know most of the T2/T25 still dont rev a whole lot higher than a diesel, my bay is a 1600 and at 4000 is doing 65-70, the Diesel in a T25 is supposed to be governed to 4500 RPM.

Also are you running stock wheels/Tyres? that can make a big impact if you have lower profile tyres at the back.

I know someone else with a converted bay, its a diesel and they have used a 2litre petrol gearbox (4speed) and said that at 4500rpm they hit the govenor and thats about 90mph!