Front diff ratio change?

[retrotec]

Can the front diff in GTRs and GTS4's have the diff ratio changed, ie to 3.7:1 (Rb30DET).

Has anyone done it before?

[Sumo]

That would mess with ATTESSA i would have thought. Unless you increased the front and the rear ratio's proportionally to each other.

I do not have a clear grasp of the finer details of how the attessa system works, but changing 1 ratio you will have the fronts (In full 4wd lock) dragging the rears - and will end up with a car fighting itself.

Thats just the mechanical part of it, I would hate to think of the computer trying to work out what is going on - I bet if it could, it would sit their scratching its head.

Cheers

Sumo

[retrotec]

That would mess with ATTESSA i would have thought. Unless you increased the front and the rear ratio's proportionally to each other.

Your right Sumo, the reason for changing the front ratio is because the rear diff has had it's ratio changed.

[Duncan]

I changed the front and rear ratios to gts4 (4.4) together in my gtr. I put in a full GTS4 sump at the front which includes the diff and its ratio. Not sure if you can just change the crown wheel and pinion to receive the same result.

[blind_elk]

You can fit a matching crown wheel and pinion set in the front diff housing (I did that fitting the GTS4's set into a RB25DET ex-Stagea housing).

If you had a 3.7 in the front and a 4.1 in the rear, then when you started getting FWD, the front wheels would try and pull the front of the car away from the rear of the car. If you had the opposite (4.1 front, 3.7 rear) then you would likely spin as the rear tried to catch up with the front.

It really makes sense to have both ratios the same.

[StageZilla]

hey retrotec ive changed gtr front diff to stagea 4.3 gears without any prob and id say they should fit easy

u gotta change the little and the big wheels in the front diff

bolts r bloody tight and required a 3/4' socket set (****in big) and a 1 metre breaker bar just to crack some of em

good luck and any probs just pm me and ill try and answer if i can

ta

Brad

[blind_elk]

I know I said it makes sense to have them both the same. But I'm in a position where I want to fit the Stagea front diff, but I need a matching rear diff.

Someone has suggested that there is some sort of slip between the front and rear, so that the ratios don't necessarily need to be identical. Is this the case? Does anyone know for certain that the front and rear ratios in AWD Nissans have to be the same?

TIA