Here's my situation. I have an 1989 F-150 5.0L 4WD. I have driven and owned several 4WD vehicle before, but when I have my manual front hubs locked in (engaged) and turn sharply at low speeds I get a very loud jerk accompanied by some strange noises. The jerking would be similar to 4WD engaged at lows speeds and dry pavement turning sharply only much worse. It makes no difference what direction I turn and if the transfer case is in 4WD or 2WD. I am suspecting front axle wheel end u-joints, but was wondering if anyone else has experienced this. Thanks!

 

Does anyone have any thoughts on this???

 

Something is not right. so the hubs are locked but the transfer case is in 2wd? I would check to make sure the transfer case is actually in 2wd. Unlock the front hubs and try to turn the driveshaft by hand. It is wont turn I bet the transfer case is stuck in 4wd. If it does spin freely the damaged part must be in the front axle. Possibly hub bearings or damaged spider gears in the diff keeping the front wheels from rotating at diff speeds

 

It's perfectly normal. Pre-'97 trucks use U-joints in the steering knuckles, and that's just how they behave when they approach their maximum deflection. It's also the REASON constant-velocity (CV) joints were invented.

Just try to avoid doing that, and avoid accelerating hard when you're steering hard. If you're stuck, do what you gotta do.

 

My U-joint at the front axle driveshaft was shot & I investigated the jerky front end a bit more per your suggestions when I fixed this. The yoke at the transfer case will turn when it is shifted from 4wd to 2wd so it does not appear to be a transfer casee issue. One thing that I am unsure of though is this. When the hubs are locked in (engaged) the front axle input yoke will not turn. Is this typical? Essentially, it would cause my driveshaft to be rotating when the hubs are engaged, but no torque would be applied at the transfer case. I do realize that the front end will have some amount of jerkiness at full turn in 4WD, but I have attemped this on fresh snowfall where traction would be limited and wheel end speed differential should not be an issue. Referencing Steve83's posted diagram, which items are you referring to for the hub bearing (4221?) & spider gear (4215?)?