How to Fix Steering Wheel Shimmy
Steering wheel shimmy, jiggle, or shake can be linked to several different problems and sometimes more than one. It does one good to note that cars are made up of thousands of interconnecting parts—some estimate there are over 30,000 parts in the average vehicle—and is a dynamic beast, which can complicate diagnosis. As a DIYer, you might be able to check some of these things yourself, but a couple of steps are best left to the professionals, with sensitive (read: “expensive”) shop equipment.
In general, steering wheel shimmy refers to visible or tactile steering wheel shake. Depending on the severity and type of shake, you might be able to see it in your hands or even see it if you loosen your grip on the steering wheel. Paying close attention to how and when steering wheel shimmy occurs will help you to narrow down the cause.
Steering wheel shimmy or vibration that occurs only at certain speeds is often related to dynamic imbalance in the tires, wheels, or axles. Vibrations that occur at low speed and worsen progressively, usually referred to as a steering “wobble” at low speeds, are likely related to physical imbalances, such as tire flat spots, bent wheels or axles, or seized joints. Steering wheel shake that only occurs when braking is most likely related to the brake system, but could also be related to faults in suspension or steering systems. Shaking that occurs just after hitting a bump is usually related to the suspension or steering system.
Several problems can cause steering wheel shimmy, sometimes in combination with one another. Tackling things one-at-a-time can help you eliminate the most common problem areas, such as:
Tire and Wheel Problems
Tire Balance: This is probably the most common cause of steering wheel shake, and perhaps the most easily remedied. Dynamic tire and wheel balance relates to how the mass of the tire and wheel assembly is distributed and how it reacts when spinning. Tire and wheel manufacturing typically results in a small amount of unbalance, which manifests itself as a vibration.
A typical tire spin balancer can detect small variations in the mass of the tire and wheel assembly, giving the tire technician the precise amount of weight to offset the imbalance.
Radial Force Variation: Tires are a complex construction of steel belts, textile belts, and various rubber compounds. Inconsistencies in the construction of the tire, variations in elasticity, strength, flexibility, or dimension, or damage, such as broken belts or bent wheels, can easily manifest themselves as a vibration. Radial force variation (RFV), also called “road” force variation, causes vibrations that tend to increase with vehicle speed—dynamic tire imbalance usually manifests at specific speed ranges.
RFV can be measured on a special spin balancer, and force-matching tires and wheels may be able to reduce or eliminate the vibration—inconsistencies in the tire and wheel cancel each other out. Damaged tires and wheels should be replaced, though some wheels can be repaired safely.
Note: When diagnosing tire and wheel problems, one easy step is to simply swap front tires and rear tires. If the shake disappears or moves to the rear, this usually indicates a tire balance or RFV problem. If no change is noted, it could mean all four tires have balance or RFV problems, or that the problem lies elsewhere in the front end.
Brake, Suspension, and Steering Problems
Brake Shake: If steering wheel shimmy only occurs when applying the brakes, it’s quite likely related to the brake system, usually “warped” rotors. Brakes may also be involved if they are dragging, always partially applied due to a mechanical or hydraulic fault.
New brake rotors may solve the problem, or an on-car brake lathe can machine the brake rotors true to the wheel hub and wheel. Inspect your brakes, especially checking that caliper sliders and pads move freely, eliminating brake drag. This sometimes happens in the rear when drivers forget to disengage fully, or at all, the parking brake or emergency brake.
Worn or Loose Parts: Worn or loose suspension components can multiply the effect of any single inconsistency in tire balance or braking efficiency. Worn or leaking shock absorbers may allow for excessive bounce after road bumps.
Check over the suspension and steering system for loose components, such as upper or lower ball joints, tie rod ends, idler arms, or bushings. Bounce-test the shocks at each corner of the vehicle. Replace worn or loose components.
Combination Problems and Other Problems
Combination problems can complicate diagnosis. One common combination problem is a worn joint or shock absorber leading to cupped or scalloped tire wear. “Obviously,” the cupped tire is causing the steering wheel shimmy, but simply replacing the tire won’t solve the problem for very long. Replacing the joint or shock and the tire will solve the problem permanently.
Something else may cause steering wheel shimmy. Common problems include the Jeep “Death Wobble,” caused by loose steering and suspension components, and older Volvo 240 shimmy caused by worn front track bar bushings. Lexus cars with certain low-profile tires would suffer steering wheel shimmy in cold weather, which would mysteriously disappear once the tires warmed up—tires would develop flat spots, sitting overnight in the cold.
There are dozens of similar problems common to different YMMs (year, make, model). In this case, it’s time to tune in to an enthusiast forum for your YMM, look for a trusted technician who specializes in your vehicle, or head to a dealer service center.
Looking at how complex the steering, suspension, brake, tire, and wheel system is, it’s easy to see how faults and inconsistencies can lead to noticeable problems. Other vibrations can have similar causes, related to wheels, tires, brakes, or suspension. You might feel this kind of vibration in the seats or center console, but you won’t feel it in the steering wheel. Diagnosis and repair is similar, but because it’s not felt in the steering wheel, you can typically rule out problems in the front of the vehicle.