A trembling car can have unbalanced tires, worn engine mounts, or misfiring spark plugs. Have it inspected.
Common causes
- Unbalanced or worn tires.
- Worn motor mounts.
- Spark plug misfire.
- Dirty fuel injectors.
- Warped brake rotors.
- Transmission trouble.
Clues
Trembles at idle: engine. At speed: wheels. When braking: rotors.
What to do
Have a mechanic read engine codes.
Safety
Don’t ignore it.
Car shake by speed and action
When the shaking happens helps narrow the cause. Vibration that starts at 50 to 70 mph and shows up in the steering wheel usually comes from unbalanced front tires. Vibration felt in the seat or floor usually comes from the rear wheels or the driveshaft. Shaking only when braking points to warped brake rotors or sticking calipers. Shaking at idle that disappears when driving suggests worn engine mounts or a misfire.
- Tire balancing typically costs about 15 to 30 USD per tire. Wheels are normally rebalanced every 5,000 to 6,000 miles or when new tires are fitted.
- A bent wheel or a tire with a bulge in the sidewall can cause a rhythmic wobble that gets worse with speed.
- Worn tie rod ends, ball joints or wheel bearings cause looseness along with vibration and noise.
- A flashing check engine light with rough shaking signals a serious misfire that can damage the catalytic converter.
When not to keep driving
Stop driving if the steering wheel shakes hard, the car pulls to one side, or a tire shows visible damage. Failed tie rods or loose lug nuts can lead to a wheel separating. After a tire rotation or wheel change, lug nuts should be retorqued after the first 50 to 100 miles. Lug nut torque for many passenger cars is about 80 to 100 lb-ft, but the owner manual gives the correct figure.
Speeds and symptoms
A car shake at 50 to 70 mph often means unbalanced tires, bent wheels or alignment. Shaking at idle suggests engine misfire, worn motor mounts or a dirty throttle body. Shake when braking indicates warped rotors. Shake when accelerating suggests axle or driveshaft issues.
Safety
Do not keep driving if the shaking is severe, if the check engine light flashes or if steering feels loose. Tire pressure should match the placard in the driver door, commonly 32 to 35 psi. A mechanic can diagnose with a road test and inspection. Typical repair costs range from about 20 USD for a balance to several hundred for suspension or axle parts.
Based on data from the National Highway Traffic Safety Administration and Consumer Reports
