4-wheel drive

[maxrules]

I suspected the front differential to be open but thought it could be a LS and cause that binding. I just don't see how those u-joints alone could cause that binding. Let's say you were locked in 4wd and going through some mud. A driver wouldn't want to turn the wheels fully to either direction if it really put that much stress on the u-joints. We need CV joints if that is the case. I still think the front differential is linking the front tires together just enought to make resistance but not cause damage. My '88 F-150 has an open rear diff, but will often spin both rear tires when I'm trying to grab traction off road. There is quite a bit of grab in that diff even when it's open.

Maybe next time I'm in the parking lot, I'll lock only one hub and see if I feel anything on turns. That would eliminate the possibility of the front wheels locking together and the u-joint would show itself.

[ScaldedDog]

[ QUOTE ]
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...There's no differential in the front axle...

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Is this really true? The stock 4WD front axle has no differential?

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Of course it does. Take a look at a Dana 50 from an Excursion here. The only thing that connects the axles are the spider gears.

BTW, my vote is that the u-joints are causing the binding sensation when the hubs are locked and the t-case is in 2WD. These aren't fancy CV's, they're just plain ol' u-joints, meaning they are not turning at a Constant Velocity (CV). There's a direct link between those joints and your hands, so it's not too surprising that you feel them change speeds in a turn.

Just my $.02, offered for free and worth every penny.

Mark

[CharlieII]

Well to answer your question simply, if you load it up and turn full lock get ready to bust a u-joint lol. That is a big no no lol. That's the absolute best way to pop a front u-joint is to turn it full lock under load. They are VERY easy to pop like that. And yes, they are binding. It's not causing the 4wd jerking, but it is the cause of the 2wd binding with the hubs locked. The 2wd locked hub jerk is more of a small shutter like a warped rotor anyway. It's only when you're in 4wd with the hubs locked that the real jerking and lurching starts at full lock on a high traction surface.

Charlie

[THE4X4PIG]

There is a lot of confused folks on this thread. Every drive axle in a vehicle has a differential. Unless it is equiped with a spool I guess. There are several differant types that are basically seperated by how positive they tie the two tires together. I do not think that there is an alternative diff or carrier for the dana 50. If you have the dana 60 there are several. I do not believe any were optioned from the factory so unless it has been changed out it is an open diff. Differant u joints can have diff opperational ranges. I dont know what the superdutys range is. I have never noticed binding while in 2wd but it could be numerous things from scrubbing of the tires to u-joints binding. Either way it is not good for the truck so take it easy. Sorry for the spelling I am tired.

[DENNY]

You can get an air locker for the Dana 50.
There is a differential in the front axle.
The u-joints cause the binding in the front axle with hubs locked and trasfer case in 2WD
DENNY

[GrampyJim]

Actually, the true working angle of a single cardan, cross and cup style U-joint is < 3.5 degrees.... anything greater than that and we can expect to experience some sort of anomally..... It will start from a mild vibration and, as the deflection increases, will work it's way up to the "hip-hop" we feel in a very tight turn.

As we increase the angle between the axle shaft and the stub shaft, the apparent centerline of the axle through the joint moves towards the "inside" angle. Now, the outside cup of the Ujoint needs to move faster than the inside cup of the u-joint to complete the same number of degrees of rotation. This mechanical connection is a little too positive for this kind of operationand we get this "whipping" sensation.....

Compare the cross and cup style joint to the CV joint used on FWD cars and we can see (and feel) the difference.

[snakyjake]

I have the problem in this scenario:
Front hubs locked.
4x.

I don't have the problem in this scenario:
Front hubs locked.
2x.

So my reckoning is that it has nothing to do with the hubs or u-joints. Since both hubs are locked, and it's moving the differential in both scenarios, then the problem has nothing to do with the differential.

That leaves only one difference, the transfer case. This leaves the possibility that the problem is caused by the speed difference between the front and rear.

I imagine the same problem happens while moving straight, but I don't notice it. But it is completely noticeable when turning.

Typically I move out of 4x when I do my tight turns. Then re-engage the 4x after my turn is completed. When traction is necessary, I do a lot of forward/reverse maneuvers. Annoying and frustrating. Not sure what other options are available.

I wonder how AWD is different? AWD is starting to sound better to me. More traction from not having the binding, and not having the concerns about open vs. LS vs. locked.

Jake