Front and rear wheels not spinning at the same speed?

[Covo71]

It just seems to be never-ending. I went out bush today and I was driving along a smooth straight dirt road and the front tires seemed to be (lack of a better description) chirping as if they were not traveling at the same speed. It has always been a bit of a pig in 4wd since I have had it. About a month or two after I bought it I had to put a new gear box in it. I have a 2004 but the gear box came out of a 2011 model. Would that make any difference? Really not going to be hard to find someone that knows more than I do. HELP!!!!

[Hodge]

Surely it can't be the gearbox as it has 1 output. Could something be locking up front momentarily, hub locks maybe? Or different diff rations front and back?

[happygu]

It wont have anything to do with the gearbox, as that just drives both driveshafts and sets of axles at the same speed.

The only time you could have a problem would be if you had different ratio diffs.

Mic

[Covo71]

Ok, next question begging to be asked as I would compare my abilities to a drunk monkey is how can I tell what if the diff ratios are different?

[happygu]

You can count the teeth on the crown wheel, but you have to open up the diffs.

I think the easiest way would be to jack the truck up off the ground, lock the hubs, whack it in 4wd, mark the front and back wheels at the top or bottom, and then spin the tailshaft to see if the front and back wheels rotate to the same spot once the wheels have done a full rotation

[BigRAWesty]

Could be a couple of things.
Different diff ratios as mentioned above. You'd hope not because that would be hammering the drive line.

It could also be different tyre sizes.
Every brand is different so if you have different tread on the fronts to the rear it could be the issue.

[Covo71]

Tyres all the same and bought at the same time. I will put it up tomorrow and give the wheels a spin and see if they line up afterwards. Thanks heaps for the ideas.

[BigRAWesty]

Yea lock hubs and engage 4wd and give em a turn.

[jay see]

If you count the revolution of the tail shaft to one revolution of the wheels you can work out what ratio you have.

[the evil twin]

It cannot be the gearbox.

If it was different ratios between the front and back diffs you should have the mother of all cases of transmission windup after about 20 metres.
That would make it a bugger to get in and out of 4WD.

If there is no windup I would maybe suspect something binding in the front

Why was the gearbox changed?
How long have you had the vehicle?
How much 4X have you done in it esp over rocky stuff for example?
Manual or Auto Hubs and if Auto are you locking them?
Does it have a front locker?