90 f150 4x4
 

Front end vibrates violently and right front binds and grinds when backing up. I have replaced the front shocks. Could this be caused by a bad ball joint?:confused:

That is possible.

Does it do this all the time, or only when in 4wd? Do you have manual or automatic locking hubs?

No, only occassionally and only in 2wd. However, I don't use 4wd at the speed it vibrates very often so I don't know if it happens in 4wd. It was auto lock but recently converted to manual locking hubs. If it starts grinding when backing up, I pull forward a little bit, back up again and the bind/grind goes away.

You may want to see if you have something hung up in your breaks. That could cause these symptoms.