Drivetrain Problems:
* Worn-out motor mounts: These isolate the engine from the chassis. Worn mounts allow excessive engine movement, leading to shaking, especially noticeable when accelerating or idling in gear.
* Transmission problems: This could range from low transmission fluid (check the fluid level and condition!), worn internal components (clutch packs, bearings), or even a failing torque converter. A slipping transmission will often cause shaking.
* Driveshaft problems: A bent or unbalanced driveshaft will cause vibrations that increase with speed.
* U-joints: Worn universal joints (U-joints) in the driveshaft are a common source of shaking, especially noticeable at certain speeds.
* Axle problems: Worn wheel bearings or CV joints (constant velocity joints) can cause shaking, often felt more strongly in the steering wheel or a specific wheel.
* Differential problems: Problems within the differential can cause vibrations that transfer throughout the drivetrain.
Other Potential Causes:
* Uneven tire wear or pressure: Improperly inflated tires or uneven tread wear can cause vibrations, especially at higher speeds. Rotate and check tire pressure. Check for tire wear irregularities.
* Bent wheel(s): A bent wheel will cause vibrations, typically felt more strongly at certain speeds.
* Brake problems: Worn or warped brake rotors can cause vibrations felt through the brake pedal and steering wheel, sometimes extending to the whole car.
* Engine problems: While less likely to cause shaking *only* in gear, serious engine issues like misfires or balance problems can contribute. A rough-running engine will often shake regardless of gear.
Troubleshooting Steps:
1. Check the obvious: Tire pressure, tire wear, and visual inspection of the wheels for bends.
2. Check fluid levels: Transmission fluid, engine oil. Low levels can cause significant problems.
3. Listen for unusual noises: Grinding, humming, or clicking sounds can pinpoint the source of the problem.
4. Test at different speeds: The speed at which the shaking occurs can help diagnose the issue (e.g., U-joints often shake at specific speeds, while unbalanced tires shake at higher speeds).
5. Professional inspection: If you're unsure, a mechanic can diagnose the problem accurately and safely. They have the tools to properly test drivetrain components and identify the source of the vibration.
It's crucial to get this checked out. Ignoring shaking can lead to more significant and costly repairs down the line, and in some cases, safety hazards.
