Diagnosing a shaking steering wheel
A worn, faulty or out of balance steering or suspension component can be felt through a vibration in the steering wheel. Either as a shimmy, jiggle, or shake. However, because multiple parts can cause this, finding the root cause can be both frustrating and time-consuming for even the most experienced technicians. Here we provide an insight into the main causes, symptoms, and fixes to help you streamline your car repair work.
The weight distribution in every tire varies slightly. To compensate for this, additional weights must be added to the wheel after a new tire is installed. Unfortunately, these weights can sometimes move or fall off, resulting in an unbalanced wheel. Even in good conditions, unbalanced tires can cause the car to shake while driving at high speeds, starting around 50 to 55 miles per hour, often being most noticeable around 60 mph. If ignored, unbalanced tire problems can wear out steering and suspension parts faster than normal, cause poor fuel economy, or lead to a blowout when driving the car.
If there is a vibration in the steering wheel, do a visual inspection of all wheels and look for any missing wheel weights, uneven tread wear, or bent rims. If any of the wheels show signs of imbalance, take the affected wheel into a technician that has access to a tire balancing machine for repair. For proper tire maintenance, be sure to rotate the tires on average every 7,000 miles, or at the very least every two years, and always ask the auto shop to balance a tire after a repair or new installation.
Another common cause of steering wheel vibration is the incorrect positioning of the wheels. In most cases, a wheel alignment will stop the shaking by ensuring all wheels are positioned in the same direction. One of the quickest ways to diagnose misalignment is to check the tire’s tread. A vehicle out of alignment will often make tires wear unevenly, with the inside tread worn much more than the outside. If you notice the steering wheel is straight and centered and the vehicle still pulls to either side, the vehicle is likely out of alignment.
Wheel alignment is achieved through suspension components, so if there are any suspension issues such as damage either through general wear, driving on rough roads, or an accident, the wheel alignment will most likely be affected. An alignment is also needed before any extended driving after a vehicle’s suspension is raised or lowered, or if a vehicle has had any new steering and suspension parts installed.
Damaged or worn wheel bearings
If the steering wheel only shakes while turning, your next go-to part should be the wheel bearing. Designed to secure the wheel hub to the vehicle’s suspension, and allow the wheels to turn properly, these safety critical components can cause steering wheel vibration if damaged or not lubricated sufficiently. Wheel bearings can be worn from driving regularly on rough roads, or damaged from hitting potholes, speed bumps, or curbs at higher speeds. Modifications to steering and/or suspension systems can also cause unnecessary wear on the wheel bearing.
Other signs of a worn wheel bearing aside from a shaky steering wheel can be abnormal noises coming from the affected wheel that gets louder while accelerating, loose or vague steering, and/or a malfunctioning ABS sensor.
Here is a quick method in determining if an abnormal noise while driving may be due to a worn out/faulty front wheel bearing: Drive the vehicle while listening for the abnormal noise. Check your surroundings while driving and if conditions allow, make a quick lane change/turn in one direction. Listen for the noise to get louder. If the noise stays the same try a lane change/turn in the other direction. If the noise changes with a directional change the noise is likely a worn out/faulty front wheel bearing. Whichever direction you turned tells you which wheel bearing may need to be replaced. For example, if you turned left you increased the weight load on the right side and vice versa. If the noise was increased in volume while turning left then the right front wheel bearing may be your culprit.
For a final determination on the wheel bearing being worn or damaged, securely raise the vehicle. Next, with both hands on the tire, in the 12 and 6 o’clock position, rock the wheel. There should be minimal movement. If it moves more than it should, or you hear a grinding noise when rotating, it’s likely that the wheel bearing is damaged. Wheel bearings should be replaced as soon as there are signs of wear or damage. If the damaged wheel bearing fails completely, the wheel could seize, causing catastrophic damage if driving.
Worn steering or suspension parts
It only takes a small amount of play or looseness in any one steering and suspension component to make the whole system noticeably slack. As well as affecting the vehicle’s control and stability, this can also cause steering wheel vibration. It’s therefore important to inspect the system for loose or worn components. Start by checking visible parts like the upper or lower ball joints, tie rod ends and bushings. If you see any signs of damage or excessive play, it is probably faulty and should be replaced. Similarly, loose shock mounts, damaged or detached springs and leaking shocks or struts can cause vibration in the steering wheel. These should be checked and replaced as necessary.
For more information on worn steering and suspension parts, check out the Delphi Technologies Resource Center article on Driving a car with worn steering and suspension parts.
If the steering wheel only shakes when stopping, and/or the brake pedal shakes as well, the braking system is most likely the problem. A shaking steering wheel can also be caused if the brakes drag due to a mechanical or hydraulic fault, or if the parking brake is engaged in error. Often referred to as brake judder, vibration when braking can be caused by brake disc run out, disc thickness variation (DTV), and/or severe disc overheating and distortion.
Brake disc run out
Vibration in the steering wheel can be caused by a poorly installed brake disc pulling out of parallel alignment with the hub or caliper. Causes of poor installation range from rust or dirt buildup between the disc and hub creating an uneven surface, over torqued positioning screws, and/or fitting a disc to a warped hub. Although a warped hub is rare, in recent years there has been an increase of use in wheel spacers that can cause excess wear to the hub. It is important to inspect brakes immediately if a vehicle has suspected brake disc run out since it can cause increased vehicle stopping time, or worse, temporary brake fail.
To fix brake disc run out, dismantle the affected disc and clean both the disc and hub thoroughly. Measure the thickness of the brake disc using a brake disc micrometer. If it’s outside the manufacturer’s tolerances, then it cannot be serviced and must be replaced. If they are within tolerance, reinstall the brake disc in an alternative position to even out the surface. When reinstalling, do not over torque the positioning screws. If run out still occurs after these steps, the wheel hub is most likely damaged and will need to be replaced.
Disc thickness variation (DTV)
When a brake disc is not properly installed, aligned, or torqued, this can cause uneven wear that makes spots thinner or thicker on the disc. Pollutants caught in the system such as deposits, rust, and dirt can even cause DTV. When a disc surface is uneven and pressure is applied to the disc by the brake pads, the brake pads will cause a pulse sensation in the brake pedal. Likewise, vibration in the steering wheel can be felt when thin and thick sections of the disc slip in between brake rotors. A warped brake disc will cause increased stopping time and possible temporary brake failure, similar to brake disc run out, so if DTV is suspected, the brakes should be inspected immediately.
A very common cause of warped disc brake rotors is over tightening the wheels on the vehicle and/or failing to employ the proper crisscross pattern when torquing the wheels to the proper specs. Never use an impact wrench to tighten wheel/lug nuts unless you use the proper torque adapter- this is also known as torque ‘stick’.
To fix DTV issues, measure the thickness of the brake rotor or disc using a brake disc micrometer. If it’s outside the manufacturer’s tolerances, then it cannot be serviced and must be replaced. If they are within tolerance, dismantle the affected brakes, clean parts thoroughly and reinstall in proper alignment. Always ensure that the hub and disc mounting faces and brake caliper carriers are clean, the slider pins are lubricated and moving freely, and the wheel fasteners and disc positioning screws are correctly torqued.
Severe disc overheating and distortion
During times of repetitive, hard braking, brake discs sometimes do not have time to cool down and will overheat. When a disc overheats, it tends to warp, causing vibration in the steering wheel and brake pedal when braking. If there are any dark blue spots on the brake disc, this is a good sign the disc has overheated. Likewise, poor quality brake pads can overheat, and cause distortion when the overheated pads apply pressure to the brake disc.
If there is any distortion that is out of tolerance in the brake disc or damage to the brake pads, they will need to be replaced immediately due to the risk of brake fade. Brake fade is when there is a temporary decrease or full loss of braking power due to overheating, but it can be easily avoided with the right brake parts. If your vehicle is prone to extreme braking from anything to towing on mountain roads or racing, be sure to purchase OEM brake pads and brake discs that are specifically designed to handle a lot of heat.
Forgetting to use turn signals when changing lanes
This almost sounds crazy but if your vehicle is equipped with an ADAS (Advanced Driver Assistance System) feature such as LKA (Lane Keep Assist), LDW (Lane Departure Warning) or similar system the vehicle is watching the road (via a smart camera) while you drive. If you attempt to change lanes without using your turn signals the vehicle’s ADAS system simply thinks you’re drifting into another lane inadvertently. This can result in the EPS (Electric Power Steering) being activated by the ADAS related system to either keep the vehicle within the lane or at least alert the driver via a vibrating seat, audible alarm or vibrating steering wheel. The fix for this problem is simply remembering to use your turn signals when changing lanes. Probably a good idea even if you don’t have a vehicle with ADAS!
Steering wheel shake can be caused by any one or more, of these, and other issues. For example, a worn joint leading to excessive tire wear. This can complicate diagnosis somewhat. It’s therefore important to diagnose and repair any faults quickly. While vibration issues can be caused by something as simple as a loose bolt or a deflated tire, they can also signal a much bigger problem. If ignored, these could negatively impact the vehicle’s safety and stability. By following these steps, you can rule out any such issues in a logical order, saving valuable time, money and frustration.