1. Safety First: Before working on your vehicle, ensure it's parked on a level surface, the parking brake is engaged, and the engine is off. Wear safety glasses.
2. Visual Inspection:
* Tires: Check tire pressure (should be as specified on the driver's side doorjamb sticker). Look for uneven wear, bulges, cuts, or any signs of damage. Uneven wear is a strong indicator of alignment or suspension problems. Replace damaged tires.
* Wheels: Inspect wheels for bends or cracks. Try swapping a front wheel with a rear wheel (if the shimmy persists in the swapped wheel, the problem is likely with the wheel, not the suspension).
* Suspension Components: Look for any obvious damage to tie rod ends, ball joints, control arm bushings, sway bar links, and shock absorbers. Look for cracks, leaks (in shocks/struts), excessive play (wiggle components to feel for looseness), or any signs of wear.
* Steering Components: Examine the steering linkage for damage or looseness.
3. Test Drive and Observation:
* Speed of Shimmy: At what speed does the shimmy occur? This can help narrow down the cause. Low-speed shimmy often points to suspension issues, while high-speed shimmy may indicate balance or tire issues.
* Steering Wheel Vibration: Does the steering wheel vibrate excessively? This points to a front-end problem.
* Braking: Does the shimmy worsen when braking? This suggests problems with rotors, calipers, or wheel bearings.
4. Potential Causes and Solutions:
* Unbalanced Tires/Wheels: This is the most common cause. Get your tires balanced professionally.
* Worn or Damaged Tires: Replace worn or damaged tires.
* Bent Wheel: Repair or replace a bent wheel.
* Worn Ball Joints: Replace worn ball joints. This is a significant safety concern.
* Worn Tie Rod Ends: Replace worn tie rod ends. This also affects steering precision and safety.
* Worn Control Arm Bushings: Replace worn control arm bushings.
* Worn or Damaged Sway Bar Links: Replace worn or damaged sway bar links.
* Worn or Leaking Shocks/Struts: Replace worn or leaking shocks/struts.
* Misaligned Wheels: Get a professional wheel alignment. This is crucial after any suspension work.
* Worn Wheel Bearings: Replace worn wheel bearings. This is a serious safety concern.
* Brake Rotor Warpage: If the shimmy is worse during braking, inspect brake rotors for warping. Resurface or replace if necessary.
5. Professional Help:
If you're not comfortable performing these checks and repairs yourself, take your E350 to a qualified mechanic. Diagnosing a front-end shimmy can be challenging, and a professional will have the tools and expertise to identify the root cause and make the necessary repairs safely.
Important Note: Ignoring a front-end shimmy can lead to more serious damage and safety hazards. Address the problem promptly.
