1998 F 150 4.6 320,000.
Just changed the driverside top ball joint( arm). Get it close as possible to where old one was. Now when I drvie it and start to get up in speed it starts to shake or shimmy. I know I need to take it in for an alinement. Is that what causes it to shake? being out of alinement or is there something else that is causing it?

 

Either your alignment is bad or you could possibly have a bent rim which would cause shaking once you reach at lest 35 mph

 

Rotated the tires and the shaking is still in the front end. This started the same day that I change the ball joint

 

ball joint normally dont throw you off alignment much. Appears to be due to that since the timing is same day, but i would jack under A frames, off ground slightly and check top and lower ***** both sides for wiggle. Also sight front to back and see if tires are somewhat parallel to the rears. Should have slight toe in at front.

 

Look for slack in the idler arm as well. I just swapped mine due to vibration and tire wear. Took about 20 minutes. My steering tightened right up. My old one only had a slight amount of slack visually, but it made a huge difference at the steering wheel. Your best bet would be to find an alignment shop that does free estimates. They will find any other loose components.

 

ANY slack in ANY of the front steering/suspension components (balljoints, TREs, idler/pitman arms, bushings) can greatly affect alignment. That's why any reputable shop won't touch an alignment until all components with "slack" in them are replaced.