Transit diff change

[transit nut]

Hi,
i havent been on here for a long time SORRY !
My 2000 LWB 2.5Di is very slow and id like to change the diff on the back axel so it would go faster n use less fuel, is it easy to do and how difficult is it to find one?

Thanx Mark

[MinorMatt]

well it depends what axle and what diff ratio you already have

[Highlander250469]

id like to change the diff on the back axel so it would go faster n use less fuel

When you say yours is slow do you mean accelerating or top end speed?

If you're changing the diff for higher top speed/lower revs/better mpg you're going to lose acceleration

If you're changing it to make it accelerate quicker you're going to lose MPG and top end speed

My 94 2.5D did about 85 flat out and took a week to get there

[transit nut]

Thanx guys.
its a 2000 W reg LWB Model 100. Im lucky to get 75mph out of her (thats on a Road Angel not the speedo ) id like a bit more top end. Dont know what diffs on her. Years ago i had a twin wheel Mk2 face lift Di with an overdrive G/Box that did 90 on the clocks. Would love this van to be closer to 90mph than 80

Thanx everyone Mark

[streetmech]

Hi,
i havent been on here for a long time SORRY !
My 2000 LWB 2.5Di is very slow and id like to change the diff on the back axel so it would go faster n use less fuel, is it easy to do and how difficult is it to find one?

Thanx Mark

It's not possible to go faster and get better mpg.
changing gear ratios doesn't remove wind resistance.
If you want better mpg you have to go slower.

Pete.

[AlanN]

This thread will help identify what you should already have... is it 5 stud or 6 stud
Although mine is a MK3, I changed from the worst axle I could have for a pleasure van (5.14) to a 3.9. Its without a doubt, the best thing Ive ever done on the van. Until I fit my V6 that is... :lol:

[MrMPuk]

If you're getting 75 then I doubt you will get a better diff, if you were to fit a better diff you would find that the van would be dying on hills.

[Highlander250469]

It's not possible to go faster and get better mpg.
changing gear ratios doesn't remove wind resistance.
If you want better mpg you have to go slower.

Pete.

I think what he actually means by faster is a higher top speed.

And a better mpg for the same speed, not the faster speed

cruising at 70 mph with a 3.9 diff will return a lot better mpg than cruising at 70 mph with a 5.14 diff (assuming the power is available to do it)

I changed the diff on a car from 3.91 to 3.36 as I do a LOT of motorway stuff, its a bit slow taking off but not too noticeable, however on the motorway it cruises about 700rpm lower than before and returns around 8 mpg more

[Wambo]

...I changed from the worst axle I could have for a pleasure van (5.14) to a 3.9. Its without a doubt, the best thing Ive ever done on the van. Until I fit my V6 that is... :lol:

Hi Allan, I too have a 5.14 and wish to change to a taller diff for better MPG. Mine is a 6 stud and the best options are in the 5 stud axles. Was your 5.14 a 6 stud? Did you put a 5 stud axle in?

[MinorMatt]

AlanN's Van was a 5 stud axle.

The best ratio avaliable for the 6 stud is 4.63

[AlanN]

As Matt says... but still look for a 4.63, remember to get the speedo pinion to go with it, out of the gearbox

[madbri]

ive got a six stud high cub with a 5:14 diff. if i fitted a 4.63 diff dose this make the top end speed more? and also if i were 2 keep it at 60mph as the old diff dose will it improve me mpg? or am i better giong the whole hog and changing the axle for a 5 stud 4.11 any issuse between 5 stud 6 stud ie law/fitting the same under van ect THANKS

[MinorMatt]

If you fit a 4.63 you will be doing less revs for a given speed - so in theory the top end should increase. If you are driving at 60 with a 4.63 it will be doing less revs than a 5.14 so I guess the economy should improve! a 4.63 will have less pulling power though, so if you are always running heavy your MPG may decrease.

With regards to fitting a 5 stud axle (I havent looked in to the legalities of it yet - but its what I am planning to do) I would imaging you would need to downplate the van as the 5 stud rear axle isn't rated as highly as the 6 stud in terms of load capacity (you will also need to tell your insurance company)

[madbri]

thanks matt if i did change the axle id pretend i didnt as the insurance would want to no the ins and outs of a dogs arse. its a camper so id just play syupid and say the last owner must av changed it ! there must b loads of wrong bits on transits that honest people dont no! but let us no bout the change over

[MinorMatt]

it will be a while yet! Im going to redrill the axle and I havent got all the kit yet!

Matt