4.1 diff or 3.9

[M50GRF]

Is any one running a 4.1 ratio diff and close ratio gearbox?
Is this too extreme would a 3.9 be ok

Also I'm going to drop 5th gear to 0.72 when the gearbox is being converted to c/r

[ShiDevil]

Hi,

I think you have asked this already on another post? Most here, will have the standard 3.43, however there is a smaller number with the 3.73 (many have moved from the 3.43 to a 3.73) and 3.91 with a CR. I find it highly unlikely that you will find many if any that would have asked for something like a 4.1, as the 3.91 is high enough from what i've gathered.

I guess the question is, what are you going to do with the car?

Steve

[Hollowpockets]

I now have a CR box with a 3.9 diff, previous owner fitted it. My engine is standard 4.0 but the car is as quick as a 4.3 with normal box and 3.46 on the move. It is a little short on motorway driving as the high revs are a pain after a while and could do with being 500rpm lower at 80mph as its pretty much all road miles I do with it.

My last one had normal box and changed from 3.4 to 3.7 diff, great!

IMO, unless its a race car, don't bother going any further than the 3.91 with CR.

If I had money to piss away I'd change from 3.91 back a step to 3.73 or whatever it is.

Graham

[ShiDevil]

Hollowpockets said:

I now have a CR box with a 3.9 diff, previous owner fitted it. My engine is standard 4.0 but the car is as quick as a 4.3 with normal box and 3.46 on the move. It is a little short on motorway driving as the high revs are a pain after a while and could do with being 500rpm lower at 80mph as its pretty much all road miles I do with it.

My last one had normal box and changed from 3.4 to 3.7 diff, great!

IMO, unless its a race car, don't bother going any further than the 3.91 with CR.

If I had money to piss away I'd change from 3.91 back a step to 3.73 or whatever it is.

Graham

Great summary Graham

[gacksen]

in my chim have a CR with 0.63 5th and 3.77 GKN and this is way enough. will change the diff on my T350 from 3.4x to 3.73 but for german standards i won´t be that funny going on the motorway as standard t5 there. if the car is only used for fun driving on smaller roads at lower speeds then go for a CR with longer 5th and 3.73 so there is an option for laid back motorway cruise instead of everytime all in flavour.

[M50GRF]

ShiDevil said:

Hi,

I think you have asked this already on another post? Most here, will have the standard 3.43, however there is a smaller number with the 3.73 (many have moved from the 3.43 to a 3.73) and 3.91 with a CR. I find it highly unlikely that you will find many if any that would have asked for something like a 4.1, as the 3.91 is high enough from what i've gathered.

I guess the question is, what are you going to do with the car?

Steve

The car is just for fun, not really interested in top end speed.
4.1 at 6500rpm in 4th = 118mph is quick enough for me but is it too aggressive in the lower gears..
I did ask this question before within a post but didn't get much response, I thought it might grab more attention as headliner.

Mike

Edited by M50GRF on Thursday 12th September 20:36