2003 F-150 4x4, 170,000

I feel a vibration when I start out with the wheels turned either left or right. The vibration quits when I straighten the wheels or when I get above a few mph in speed. When starting out with the wheels straight there is no vibration.

I had the hub and wheel bearings replace, but that did not solve the problem.

Thank you

 

Sounds like the front axle 4wd Actuator has the front axles locked together.
When the front is supported off the ground does both front wheels turn together at the same time?
If yes, this is your problem.
Be sure 4wd is not turned on or the Actuator has not locked up the front axles for some reason.
There is nothing else that would cause the front wheels to 'sprag' off straight ahead like that.
Good luck.

 

If it were me, I'd very carefully inspect the boots for the outer and inner CV joints on both axle half-shafts. Looking for cuts/splits/tears and/or clamps loose/broken. If grease goes out, grit comes in, and will start to cause a CV joint to stick/slip as it rotates WHEN the half-shaft is not straight.

As the wheel is steered sideways away from straight ahead, the ***** in the outer CV joints start to run up and down their tracks per wheel revolution. And the bearing wheels in the inner tripot CV joint also run up and down their channels per wheel rev. Any grit or lack of lubrication will cause problems, and lead to eventual joint seize-up or destruction.

With 170,000 k miles on the truck, have the half-shafts ever been replaced?

This is a common FWD car problem. Usually the outer CV joint is the one that splits its boot or fails on its own internally first, rather than the inner CV joint, which has an easier job, which is why the inner has a simpler and cheaper joint design.

I'm not saying this HAS to be the problem you have, but it is worth checking out.

 

you have a limit slip rear axle and the friction modifier is worn out...... If you have not changed the fluid 1-2 times since new, do it now... If you have good gear lube inside, then go to Auto Zone and get a 7 oz bottle of friction modifier and add to the rear axle gear lube.