1. Wheel Balance and Rotation:
* First Step (and cheapest): Get your wheels balanced and rotated. An imbalanced wheel is a common cause of high-speed shimmy. Uneven tire wear can also contribute. This should be your absolute first step.
2. Tire Condition:
* Inspect Tires Carefully: Look for:
* Uneven wear: Cupping, feathering, or excessive wear on one side indicates suspension or alignment problems.
* Bulges or damage: Any damage to the tire sidewall can cause vibrations.
* Proper Tire Pressure: Ensure tires are inflated to the manufacturer's recommended pressure (found on a sticker inside the driver's side doorjamb).
3. Alignment:
* Get a Professional Alignment: An improperly aligned front end is a major culprit in high-speed shimmy. A shop should check:
* Toe: The angle of the wheels pointing inward or outward.
* Camber: The angle of the wheels leaning inward or outward.
* Caster: The angle of the steering axis.
4. Suspension Components:
* Inspect Suspension Parts: These components can wear out and cause vibrations:
* Ball Joints: Check for excessive play or looseness.
* Tie Rod Ends: Similar to ball joints, check for play.
* Control Arm Bushings: Worn bushings allow excessive movement and vibration.
* Shocks/Struts: Worn shocks or struts can contribute to a shimmy, especially at higher speeds. They don't necessarily have to be completely "blown" to cause this.
* Steering Rack Bushings: These can wear and cause play in the steering system.
5. Other Potential Issues (Less Likely but Possible):
* Wheel Bearings: Worn wheel bearings can create vibrations.
* Driveshaft: Although less common, a worn or unbalanced driveshaft *could* contribute. This is less likely to cause a shimmy only in a specific speed range.
* Brake Rotors: Warped brake rotors can cause vibrations, but usually at lower speeds or when braking.
Troubleshooting Steps:
1. Start with the simplest and cheapest: Wheel balance and rotation.
2. Thoroughly inspect tires: Look for wear, damage, and ensure correct inflation.
3. Get a professional alignment: This is crucial.
4. Have a mechanic inspect the suspension components: This requires more expertise and might involve replacing worn parts.
Important Note: Don't attempt to diagnose or repair suspension components yourself unless you have significant mechanical experience. Improper repair can be dangerous. Take your car to a qualified mechanic for a thorough inspection and repair. Be sure to mention the specific speed range (63-73 mph) of the shimmy to help them pinpoint the problem.
