Front Diff Locking or Not?

[argonaut]

I've had my Blazer for about a 6 months now and I'm hoping to take it up to Hungry Valley this weekend to do a little light wheeling for the first time (first time for me, and first time for this truck), not planning on doing anything too crazy. I really just need to get out of LA for a couple days... but I digress.

So anyway tonight I was checking everything out mechanically, checking fluids, and finally locked the hubs and threw it into 4HI. Everything was fine until I tried to turn a little bit of a sharp turn and was hearing a front tire screeching. I thought to myself cool, maybe there is a locking device in this front differential and I didn't even know it! But when I jack up the front end and spin one wheel, the other spins in reverse just like an open diff.

So whats the deal here? Am I missing something?

 

[bp71k5]

4wd on pavement will do that in sharp turns. Mine doesn't screech, but bounces around like crazy. You might check the front axle ujoints to make sure they aren't binding during the turn, but it sounds normal.

 

[resurrected_jimmy]

As said above, sounds like normal binding if the tires can't slip. As far as your test went, its an open fromt diff

 

[69TowRig]

The reason why you get the bucking and screeching is due to the 4wd system trying to turn the front and rear wheels at the same rate. In a turn, the front axle actually travels a longer distance in an arc. It is even worse when you have an LSD or locker in the front.

 

[argonaut]

Oh, I hadn't though about front versus rear rotation but that makes total sense.

 

[70jimmy]

Same holds true for the front tires. The one on the inside of the turn travels less distance than the tire on the outside so one of the tires needs to break traction momentarily when the hubs are locked.

 

[argonaut]

Same holds true for the front tires. The one on the inside of the turn travels less distance than the tire on the outside so one of the tires needs to break traction momentarily when the hubs are locked.

Given that this is an open differential I don't see how that could be true.

 

[LVJimmy]

Did you spin the wheel once or a bunch. A loose posi unit will spin like an open diff for a few rotations until the oil wears off of the clutch discs.

 

[70jimmy]

Given that this is an open differential I don't see how that could be true.

Open shouldn't matter, but limited slip, or locker would.

More than likely it is as was pointed out the binding from front to rear with the axles having the same gearing and the front tire on the inside of the turn binding with the rear and one tire has to give and the rear tends to push the front.

Mine does buck a little with one hub locked and steering and actually having the vehicle go where you want with both locked is a fantasy.