Ed the Patriot

Recent snow storm wife puts the truck in 4HI everything seems to have gone into gear but as she drives the front wheels seem to be twitching from side to side while the truck is going straight. All she can do to control the truck from wrecking was hold the steering wheel tight as she could. As soon as she shifts back to 2HI all is fine. I put the truck in 4Hi myself and it did the same thing trying to throw the front end side to side every few feet. Can anybody tell me what's going on with it?

tech2

not sure.
any mismatches with the tire sizes?...it may cause a driveline bind up condition

Ed the Patriot

All the tires are the same size and nearly new.

JDKD2008

Do you have the Torsion bars cranked up?

Ed the Patriot

I replaced the stock keys a couple of years ago with ones from a 2.5" rough country leveling kit. The front end does sit an inch or two higher than the rear. There is also a few hundred pound load in it right now.

JDKD2008

I am willing to bet that is your problem. The reason i say this is when i cranked up my keys the truck did exactly what you described. I lowered them backndown and problem was fixed. Then i decided to just do a complete suspension lift and no problems. I think it has to do with axle angle and weight distribution. If your front end is up its putting more weight on the back. Hope this helps. Let me know what you find out.

Ed the Patriot

I really appreciate your reply. That makes the most sense I've heard. The front end being up would require more axle length, maybe the splines are barely engaging? I'm going to lower the front this weekend and I'll post the results. Thanksfor the help.

JDKD2008

Your splines are good as the get bolted through the hub with the axle nut. I think its more of the axle angle than any thing. The straighter the axle, the less torque on the u joints. See vid below. Its cheezy but explains the angles.
https://youtu.be/LCMZz6YhbOQ

Ed the Patriot

Good video, Thanks, My truck has 2 CV joints in each axle but I'm sure they have their limits. I'm definitely going to lower the front end this weekend and see if the problem goes away. Thanks, much appreciated. I will also change the oil in the front diff while I'm under there.

Ed the Patriot

It took me a while to get to lowering the front end of the truck but after backing off the torsion bar adjustment bolts roughly 8 turns and leveling the truck, The four wheel drive problem has gone away and the truck drives like it should when placed in 4 Hi.
I really appreciate your help and hope this helps someone else with the same strange problem. Happy New Year to you all. Thanks You so much.