Mystery Shimmy

[ex man in van]

Hi guys. Got an unusual situation here.
Today I took my 96 Explorer in for the front bearing/hub replacements that my dealer offered to do under the warranty.
Great! They used quality SKF's. Took an hour and a half and I was on my way.
So cruising back home and aproach the intersection where I turn right.
As I slow down and make the turn, my steering wheel starts fighting me and shaking rapidly, almost like the right side brake was grabbing and ABS was actuating WTF? I thought " maybe one of the new ABS sensors is not hooked up given the rapidness of the pulsing (Thought also that possibly the fin count on one of the hubs may differ from the other but propably a long shot.) ...but no light. Get out and look on both sides. yep....all good. Maybe the new sensors are different, and communicating with the computer.....Hmmmmm......So I drive a block, pull over, shudders again, but I turn off the engine, wait a minute then start up again and take a few more side streets making lefts and rights.
The rights seem the worst.

I say screw it, and drive back to the shop for them to take a look. My thought now is maybe a spline problem in one of the bearings.
Guy comes out and is baffled.
We take it for a drive, and seems to have gone away (of course) but just as I was looking like a complete git, he makes the last turn and it fights him with the same shaking.

He seemed to think it sounds and feels like the power steering. The fluid is full and seems ok.
It makes a bit of sense, it seems louder since leaving the shop, but it just seems like one hell of a coincidence. It's been running perfect right up to this morning. Can steer with one finger if I want.
So anyway, with that suggestion, I do the old lock to lock bleed trick, and it seems to have gotten a bit better, but I'm still a little freaked. I do a lot of highway driving, and the last thing i want is to have a situation where I can't steer the truck properly at highway speeds.
so.....any of you have any ideas? One thought that crossed my mind was maybe when they were torquing on the bearing, it may have bound up the front diff clutch or something. |Could this explain the louder pump operation because it's working harder to override the road friction?
Please...Any ideas of what to look for would be helpful.
Just weird.

 

[ex man in van]

So just got a bit of info that might explain it, but also raises a few other questions.
I was told that if the mechanic manually turned the steering from the axle without the engine running and the steering pump rotating, (like to access the three bolts in the back to remove the bearing,) this can actually cause air to be drawn in to the system, and can make the steering shake quite violently.
This would make total sense as after a while it seemed to go away but only after an extended period of moving the steering left and right, and a few of those turns the pump was really groaning... I could hear it through the steering wheel!
So where does this air enter the system? Like I said the fluid is bang on the line cold, and when warm is where it should be too. Is there a check valve somewhere that needs changing? I don't appear to have any leaks, and my fluid level has not dropped at all.
Good news if it's true because no damage to the new bearing or diff which had me pretty nervous....but potentially bad if I need to spend more time tracking a new steering problem down.

My concern is that this is intermittent, and I just want to avoid a dangerous situation if it were to happen again like on the highway.