kylezx7r

Hi


I know there is threads about this subject already but none of them are directly related to what I need to I have started my own.
I have a low mileage 2009 mark 7 transit 2.4 RWD 100ps LWB.
since buying it ive notice its horrible to drive on motorways due to the 5 speed box, im also guessing the diff ratio is low aswell but im unsure how to find out exactly what ratio it is.


I was going to change the gearbox for a 6 speed box but ive since read on here that perhaps this would make no difference and I should be concentrating more on the diff ratio. I'm not interested in speeds or acceleration as the van is very rarely laden (Only carries and motorcycle and some tools) im more interested in reducing the engine
revs at motorway speeds to increase MPG and also just make the engine more comfortable.
I am an oil rig mechanic so tempted to do it myself but ive never set back lash etc so I think I will get my local garage to do the work.


So my questions are:
1. How do I find out what diff ratio I currently have?
2. What parts would I need to change it to a higher ratio for better motorway driving?
3. What ratio would give me the best motorway driving?


Any other advice / knowledge and wisdom would be much appreciated.

kylezx7r

Hi further to my post,


I have managed to find out that I definatley have a 5.11 ratio rear diff, so basically I need to know whats involved with making the ratio higher for motorway driving and what parts I need.


I appreciate any help.


Kyle

bj928

i have been looking at mk7 axles for a project of mine, best ratio i found was 3.31, that would almost half your revs at a given speed, way better for motorway use, if i was changing ratios i would swap the whole axle, its the easiest option i would have said, they do a 3.55 as well, depending on load carrying you may net have the power to pull the 3.31, what model is the transit, guessing a 330 or 350 as its rwd, single or twin wheel

kylezx7r

Its a 350, It very rarely has any weight on, its used more as a car, although I do tow my caravan on the odd occasion so that might effect it quite abit. Ive managed to find a 3.31 ratio axle and I was thinking of remapping the engine just to get that bit of extra torque??

bj928

is that 350 van or pick up, with a remap i would have said its ok to go with the 3.31, but either a 3.55 or a 3.31 would be better than the 5.11 u have now.

kylezx7r

Ah ok, So if I have an axle in front of me with no marking or plates how do I find out what ratio it is. I tried rotating the input shaft to 1 rotation of the wheel and it came out at a 1.8 ratio which is obviously wrong so how do I find out what ratio it is?

bj928

normally a tag on the back of the axle

kylezx7r

There is a tag on the diff cover but it's too corroded to read anything.

bj928

they get rusty, but with wire wool or wire brush u can normally clean enough to read

saul1988

ur never gonna get great economy out the rwd transits. I had a 350 135 crew cab and on motorway it only got 23 mpg and my mates 100 lwb hi top only does 27 at a push.

Steve Cooper

iTrader: (1)

Just so you have got a idea, my transit is a mk7 2.4 rwd but it's the 115ps with 6 speed box. I'm sure my axle is a 3.77 or something like like. It's perfect on the motorway. 2500rpm is 70-75mph 3000rpm is about 90mph. I think a ratio even lower than that would have the opposite affect and make your mpg worse.