Differentials, 4.09 front, 4.10 rear

It is not a bad idea to have it that way but sometimes it is because the series of axles that they are using only come that way. It used to be pretty common long ago but you do not see it that way today on new vehicle much at all anymore.

----------------- TheSnoMan.com

Okay, imagine what happens with a four-wheel drive system where the front wheels are turning at a different speed than the rear wheels when you're going straight down the road.

Not a good idea.

--scott

From the Randy's Ring and Pinion web site; Myths about differentials "The gear ratio in the front of a four wheel drive has to be different from the front so the front wheels will pull more."

--------------------------------------- "There have been many different ratio combinations used in four-wheel drive vehicles, but not so that the front will pull more. Gear manufactures use different ratios for many different reasons. Some of those reasons are: strength, gear life, noise (or lack of it), geometric constraints, or simply because of the tooling they have available. I have seen Ford use a 3.50 ratio in the rear with a 3.54 in the front, or a 4.11 in the rear with a

Actually this happens all the time and this is why you do not use convential 4x4 on pavement. It happens because of minor differences in tire rolling radiuses due to inflation and load and when ever you turn because the front and rear axle have different rolling paths in a turn. Also, the ujoints in a solid front axle that allow you to steer the axle under power are not constant veleocity and the sharper you turn, the more the speed across the joint varies as it flexs (this is why the wheel can whip and bind in a tight turn with a solid front axle on a hard tractive surface.

----------------- TheSnoMan.com

That's what 2WD mode is for ;-)

No they do not today because I have a 79, a 89 and a 2000 that all have the EXACT same gear ratio front and rear. BTW, Detriot knew about the bind many years ago and promotted fulltime 4x4 with a differentail between front and rear axle (I have one still) from 1973 till 1979 until fuel cruch killed them off as they were more thirsty. It was a very slick setup though speaking from first hand use of one for over

----------------- TheSnoMan.com

How does that work for you off-road or on loose surfaces? I would guess that a differential between the front and rear would lead to a greater likelyhood of getting stuck because both wheels on one axle lost traction and one wheel on the other axle lost traction at the same time. I have heared of some vehicles (newer Jeeps for instance) in which you can drive in "all-wheel-drive" mode (i.e. center diff), then lock the center diff for 4x4 mode.

Not enough difference to matter. Tire pressure differences would have the same effect as would changes in load.

- Regards Gordie

Yup, that's true.

Is it enough to seriously impact tire wear, though?

--scott

Sounds like a bunch of hooey to me.

I was always under the impression that you never use 4WD on hard pavement and that was the reason. This was told to me back in the 70's...

A few more free opinions: (1) the difference is less than 1/4 of 1%. The difference among the tread depth and inflation of your tires is apt to be of more consequence, and even they aren't likely to be significant. (2) It's not a good idea to run your 4WD on a hard dry surface, anyway. If it's soft, sandy, or wet, the slippage will take care of any minuscule issues. (3) Unless your travel is absolutely straight, the distance traveled by the front and rear tires will be different, because the front wheel axes rotate on the kingpins/ball joints, while the rear wheels are stuck in their orientation.