389 Steering Problems

wowsers 2012!!! truck with issues holy crapper...

you replaced gear box? wow do the other trucks in fleet have front steer axle airbags? could be just the normal feel of the airbag front suspension.Although i drove a 379 pete with front air bags and never felt this before.

maybe its a manufacturer recall.

 

Make sure the axle is not in backwards. I know of a older truck that had the axle replaced and they put it in backwards. He drove it for a month like that. He said it never felt right and that it was jerky.
I am almost positive that the ID tag is supposed to be toward the front. Maybe check your other trucks to be sure.

 

If you have a Hendrickson Airtek axle, this is one of the characteristics of this axle. It is more "springy" than a regular cast axle. Hendrickson was placing a composite thrust bearing on the left side of the axle to help dampen the shake you are experiencing. You will need to check if one side thrust bearing looks different than the other side, if they are both the same chances are you need one installed. We had one customer a few years ago with brand new unit with an Airtek and we replaced everything bolted to that axle. We played with the caster settings and nothing changed nothing. The rep from Hendrickson had to come down and road test the unit. After he drove it they authorized us to replace the whole beam. The beam wasn't tempered correctly. After that it was better, but still had some shake. We ended up installing a steering stabilizer and the customer was happy after that. We still see that same truck today, with a different owner, but everytime I drive it it still has that little shake.

 

Is the ride height set correctly?
its probably not the problem, but is a easy check and it will cause bump steer if is to far off.
the bar off the pitman arm going back to the axle should be level.

 

Correct, except on the previous post I left the little word about out in front of level
A rise to the front is normal and necessary , especially with springs as ride height is dictated by load, air ride not so much.
The higher the rise / angle the more the the truck will steer to the right as the body goes down in a bump situation, or body roll.