HELP! Wandering-Loose-Drifting Steering

I have been looking through the forum for a few days to figure out what is causing the steering on my 2002 Explorer XLT to wander when driving "straight", and particularly noticebale at higher speeds...say above 40 MPH. I noticed that when turning very slightly to the right or left the wandering does not exist. If am lucky enough to "quiet" down the wander by making slight wheel adjustments, it can be easly set off again from a bump in the road. It feels very unstable.

Based on the posts that I read (most of them I listed below for future readers) I've used to trouble-shoot:

I lifted the front end up:
Checked all my suspension components:
- upper and lower ball joints- and they are very solid on both sides.
- I pulled each tire from top and bottom - no looseness, and front and back - again, no looseness.
- the sway bar links are new - I replaced them a few months ago.

I also checked the steering linkage componenets - and they all appear solid as well.
- no looseness when I push or pull each wheel from under the vehicle. I tugged on each tie-rod (Left and right), inner and outer, and they are solid.
- I had my daugher get in the vehicle (with the engine off) and turn the wheel one rotation to the left and then to the right several times, while I put resistant pressure on both tires (while laying in the middle under the vehicle), and I felt no looseness or sloppiness whatsoever.

I am curious if the gear box (rack and pinion) is bad. With the engine off and turning the steering wheel left and right (as mentioned above) I didn't feel or see any sloppiness... could it still possibly be bad? I have read that earlier Explorer gear boxes (rack & pionion), have a gear wear adjustment on them. Does the 2002 gear box have one? It sounds like a remove and replace of the gear box is a pain, so I want to make sure that it is the problem before taking it out.

The XLT has a little over 141K miles, and all the suspension and steering components are original...but are still solid from what I can tell - I've been pretty careful to keep all the components lubed regularly.

Any other diagnostic tests that I can try?

Are there any available diagrams or pictures to show the remove and replace steps of the gear box (rack and pinion)?

Thanks for any help. I still have my car up on stands...

Reference Links:

Problem Removing Steering Rack http://www.explorerforum.com/forums/showthread.php?t=96196&highlight=remove+steering+gear

Removing Steering Rack from Vehiclehttp://www.explorerforum.com/forums/showthread.php?t=124961

How to: Rack & Pinion Removal:http://www.explorerforum.com/forums/showthread.php?t=150850&highlight=remove+steering+gear

How to Remove and Replace Steering Gear Box:http://www.explorerforum.com/forums/showthread.php?t=301428&highlight=remove+steering+gear

2002 Explorer Steering Assembly Parts Diagram - Parts:http://www.parts.com/oemcatalog/ind...2830&callout=1&catalogid=2&displayCatalogid=0

2002 Explorer Suspension Assembly Parts Diagram - Parts:http://www.parts.com/oemcatalog/ind...070&callout=12&catalogid=1&displayCatalogid=0

2002 Explorer Power Steering System Diagnosis & Diagrams: http://www.scribd.com/doc/14896083/2002-Explorer-Power-Steering-System-Diagnosis

Explorer Steering Problems - Diagnosis: http://www.carkb.com/Uwe/Forum.aspx/car-maintenance/11474/2000-Ford-Explorer-Steering-Problem

Wandering Steering: http://www.explorerforum.com/forums/showthread.php?t=237079&highlight=steering+wander

Wandering Steering: http://www.explorerforum.com/forums/showthread.php?t=240749&highlight=steering+wander

Loose Steering: http://www.explorerforum.com/forums/showthread.php?t=169840

Replace Steering Box: http://www.ehow.com/how_8003144_replace-steering-box-ford-truck.html

Signs of a bad Steering Rack and Pinion: http://www.ehow.com/list_6458927_signs-bad-steering-rack-pinion.html

How to Diagnose Power Steering Problems: http://www.ehow.com/video_5103506_diagnose-power-steering-problems.html

You might want to check rear suspension, wheel bearings and toe links are common. It also could be alignment concern.

Mac,
I had a very similar problem to what you are describing.
Check my post here
http://www.explorerforum.com/forums/showthread.php?t=312249
swetrid nailed it on what was wrong with mine.
Bad right rear wheel bearing and it is all better now.
I can not even begin to describe how "unstable" my car felt on the highway.
I felt like I was all over my lane and had to steer to just stay in my lane.
Check those bearings in the rear, if they move with just your hands imagine the force and movement under a load.
Good luck and keep us informed.

my1zamboni,

You are spot on!! My driver's side rear bearing is shot. I'm amazed that there was absolutely no grinding sound that typically comes with a bad bearing.

I must admit I'm a bit embarrassed that I didn't catch this. After I inspected the steering controls yesterday, I lifted the passenger side rear and checked it out, and was fine. I just gave the driver's side rear a visual looksie and it appeared fine. The reason I didn't lift the driver's side...well because the wife had it parked too close to the garage wall... stupid I know. I'm just thankful the wheel didn't depart becuase it's bad.

Anyway, thanks so much for pointing me back to the rear again. I'll be working on it tomorrow - memorial day.

THis is the best auto forum in the world!

Same here....no grinding. I wasn't convinced that the bearing was my only problem until we replaced it.
Mine had completely come apart inside the hub. We had to use a welder to get the raceway out, that was actually the hardest part of the job was getting that out.
Good luck with the fix and let us all know how it feels after the fix. Mine felt like a whole new ride after it was repaired.

I'll bump this old but useful thread. I have replaced the front upper control arms and the outer tie rods, then got an alignment. Although the ball joints on the upper control arms were worn out, replacements did not help the steering wander. Everything else looked okay.
I checked the rear wheel bearings after reading this thread and found that the drivers side is really loose.