different diff ratios

Terry, if he had a diff between the front and rear axles it would be a means of balancing torque. Having a locked front/rear connections in the simplest transfer cases like a Hilux a recipe for trouble. When engaged as 4wd on a hard surface, instant wind up of transmission, diffs front and rear as soon as you progress in any gear. Immediate wear of tyres and gear trains, lower available power as one diff either tries to overtake the other or pull the chassis apart.

Is he intending to have the numerically higher one at the front or the rear? I'd be terrified too......

If he wants to bust his G,box,diffs drive shafts etc tell him to go ahead. Windup is bad enough without adding to the problem. Barnray

Up to a couple of percent difference is OK. As an example the old 1980-1983 Subarus had a 3.88 front and a 3.9 rear. You can realistically get this effect by having a heavily loaded vehicle in 4WD anyway.

As for running (say) 3.9's and 4.1's (5%) that might be a bit of an ask on hard surfaces but OK on loose surfaces. Any more of a difference than that is asking for some peculiar and potentially dangerous handling

As advised above, make sure the front is numerically lower than the rear (rotates more per driveshaft rpm =>forced understeer), otherwise it would be a handful, and very dangerous particularly down slopes.

In a word "BANG"

Hi Terry,

In a part time 4WD, it's a very bad idea.

Tell him he can go ahead with it, but he should also get a spare drivetrain before he starts. It won't be long before he's swapping out broken bits.

What is it he wants to achieve by doing this anyway? I can't possibly see why he would want one set of wheels spinning at a different rate to the other.

VERY briefly LOL

This is already done with the transfercase having a different ratio front to rear whichis the cause of windup on hard ground. HOWEVER it is minimal compared to different ratio diffs (I think about 48:52) . would call it a stupid idea but i had a mate who turned the diff over in his litestout to jack up the back end and ended up with 4 revesr gears and one forward. Different ratios front to back is just as smart