Truck is 85 F150, 4.9, NP435, BW1345, D44ttb Open diff.

Today while driving my commute across the city, I thought I felt a faint vibration on the highway. Sure enough, a u-joint was going bad, and wearing through the caps, and had extreme play. I pulled the rear driveshaft to get me by until I can get a new joint tomorrow and have been driving on the front axle with the transfer case in 4HI.

It's working fine but not without some weird handling, that I'm not sure is normal or not. I'm just wondering if somethings wrong with the transfer case or front axle. The front axle is definitely an open diff.

1.The truck very slightly veers right when cruising, and pretty badly under acceleration.

2.If I turn a corner rather sharp (in a parking lot, or at a stop sign) the steering wheel will wobble up to 4 or so inches as if it doesn't want to turn. It didn't do it however as I turned sharply pulling into my parking spot tonight with the truck in neutral though so the steering may only wobble when in gear.
-I's also always done it a small amount in real 4x4 on a dirt or snowy road but it never bothered me.
-The only idea I have is it's slack in the transfer case chain.

3.When I accelerate the truck twists and the front end picks up a bit. If I floor it it's probably enough for a bystander to notice the body roll, and enough to shake your head around.
-It also does this a tiny bit when in real 4x4.

 

Yep normal if in 4x4 and ONLY using the front axle to move the truck.
When small front wheel drive cars started hitting the streets they did almost the same thing under acceleration - it's called torque steer.


You have to remember your truck was built to use the rear axle most of the time and the front axle to "help" the rear axle.


Also had a buddy do the same thing you did when he has issues with the rear drive shaft went bad in his first gen Bronco. He said it did the same thing as yours till too much drink and foot to the floor starts - no more front axle gears.


I say if you have to drive it on the front axle only take it vary easy and get the drive shaft fixed ASAP.
Dave ----

 

Sounds like everything should be normal. I'll have that joint fixed today.

Thanks.