Front End Shimmy

Tire out of balance.
Tire and/or wheel out of round.
Excessive wheel runout.
Insufficient or improper caster.
Worn suspension or steering system components.
Defective shock absorbers.
Wheel bearings worn or loose.
Power steering reaction bracket loose.
Tire stiffness variation.
Steering gear rack or box mounting loose.
Steering gear adjustment loose.
Worn spherical joints (front wheel drive).