The road or wind conditions are poor.

1. Test drive the vehicle on a flat road.
2. Turn the vehicle in both directions.

The front wheels are misaligned.

Adjust the front wheels to specifications.

An unbalanced steering gear valve.

If the steering gear valve is unbalanced, the steering effort will be very light in the direction of the lead and heavy in the opposite direction.

Replace the steering gear. Refer to Steering Gear Replacement .

The steering shaft is rubbing the I.D. of the shaft tube.

Align or replace the steering column.