After installing new wheel bearing hub assemblies on my 98 f150 4x4.. Driving down the road it darts back and forth hard to hold strait.. It never done this till after new hubs. All joints appear fine even adjusted steering box. Double checked my hub install. Everything looks good. Alignment checks out good sreering box is in good shape near as I can tell. New idler arm for good measures. Anyone had this problem before? If so please help, my truck has to see alot of highway time. Its makin me nervous.

 

I would have the alignment checked out. When you start replacing stuff, and you stuff in the front end starts getting moved around.

 

No on a 98 f150 4wheel nothing gets moved around when u change new wheel bearing hubs. Not anything with the steering at least. Hub bolts strait to the steering nuckle dont even have to drpp a tie rod

 

What about steering box... If its just a bit to tight when u adjust it woould that cause it ?

 

Not sure about the 98, but on the 02 the wheel bearing hub assembly does NOT come with the bearings. You have to pack them and put them in yourself. And there are two for each hub. Not greased well? or maybe not seated well?

 

That is a main sign of ball joint failure and those things can go at any time even when almost new.
I had the same exact thing on my Crown Vic and the Ford dealership diagnosed it as ball joints, replaced all of them, and the car steering is as tight as a Porsche.
The Ford mechanic said if moisture or dirt gets in the joints, they are toast.
You cannot tell by looking at them or their age.

 

No on the 98 it is a sealed unit. And I had one bad ball joint and replaced it and truck still does it. Everything else is tight. With the exception of the joint at end of the pitman arm its maybe questionable