93 F 150 front end issues
 

Hey, I just joined up to see if I can get some assistance. My son has a 93 f150 extended cab 4x4, 5.0 automatic 169,000 miles. We just put a 6" Rough Country lift in it back in May. Had the alignment done at the local Ford dealer whom I trust. The tie rod ends, radius arm bushings, right upper and lower ball joints have all been replaced as has the inner and outer wheel bearings and cups. Left upper and lower ball joints had been done before we bought the truck.The truck checked out fine and has been providing my 18 y/o with a lot of fun. However, it started to develop a very bad vibration that felt as though it was coming from the rear. After replacing the shocks and it still doing it, I followed him and when he hits a rough patch of road, like on a sealcoated road, the front wheels wobble all over. My next door neighbor is a former Ford Service writer and we tested some things and it looked like a worn steering box. We just replaced it today, my son took it for a test drive, seemed to be okay. Then, it started doing this uncontrollable shimmy. He is pretty heartbroken right now as we have been chasing this for a month. I checked underneath and one area of concern is the front axle on the right side, there is a slip type joint and that is now visible and starting to show grease. Likewise, when he was driving the truck over to the shed on some uneven grass, the wheels look like they are moving front to back as he is idling along. Could it be the drag link? We have replaced just about everything else on the front end short of rebuilding the front axle. Any help you can provide is appreciated! Hate to see my son so down.

Don't know much about the slip yolk or lifting these trucks. But have you looked into a stabilizer shock for the steering? I believe lifting the front end without a stabilizer can cause it to wobble. Also, the front wheels are kept from moving back and fourth by the radius arm, which has bushings that can go bad. Each bushing has 3 parts: 2 rubber bushings, and 1 plastic spacer. The plastic spacer can crack and fall out and it might not be noticed visually.

If the wheel is moving back and forth within the wheel well opening, I'd go with what Allfordsguy said - radius arms.
The radius arms are those 2 arms that go back to a bracket on the frame and hold the wheel in place (in a back to front direction).
A 6" lift should have included dropped radius arm brackets that get bolted on to replace the original ones. Those bolts may have come loose if they weren't tightened enough, or the big nut on the very back of the radius arms may have loosened (or the bushing may be toast, but they should have been replaced when the lift kit was installed).
I'd suggest that you have him sit in the truck with his foot on the brake and have him go reverse forward reverse a few times giving just a little gas after the gear change, holding the brake a little to keep the front wheels locked while you watch those arms and brackets real close to see if they move.
He doesn't want to bang it back and forth, just into forward a little gas, into reverse a little gas. Or block the front wheels real good front and back and do the gear change thing.
Yes, that could easily cause what you're describing.

I second what Chris says, that's what it sounds like to me, as far as the back and forward motion. Anything that's leaking grease at least deserves further consideration but seeing my truck is a 2 wheel drive, I won't be of much assistance in that area. If you could post a few pictures of the radius arm bushing and bracket (one from either side preferably) and a few pictures of this "slip joint" in question. We may be able to offer more guidance if we can see what you see.