A car that shakes when accelerating is one of the most common yet concerning issues many drivers face. You might notice your steering wheel vibrating, the seats trembling, or even the entire vehicle shaking when you press the gas pedal. While it might seem like a small problem, it can be a warning sign of deeper mechanical issues that shouldn’t be ignored.
This shaking usually occurs when you accelerate from a stop, maintain certain speeds, or even idle. Whether it’s a result of worn-out engine parts, wheel imbalances, or issues in the drivetrain, diagnosing the exact cause is crucial for maintaining vehicle safety and performance.
Let’s dive into the most common causes of car shaking during acceleration and how you can fix them before they turn into expensive repairs.
Broken Motor Mounts
One of the most common culprits behind car shaking during acceleration is broken or worn-out motor mounts.
Motor mounts serve two main purposes:
- They secure the car’s engine to the vehicle’s frame.
- They dampen engine vibrations to ensure a smooth and quiet ride.
These mounts are typically made from rubber or polyurethane to absorb engine vibrations. However, over time, the rubber can wear out, crack, or break due to constant exposure to heat, engine torque, and movement.
When this happens, the engine is no longer held firmly in place, causing it to move excessively and vibrate throughout the car. The shaking usually becomes more noticeable during acceleration since that’s when the engine produces the most torque.
Solution:
If you suspect a broken motor mount, have your mechanic inspect it immediately. Replacing the damaged mount will not only reduce vibration but also prevent further damage to other components connected to the engine.
Deformed Driveshaft
In rear-wheel-drive or four-wheel-drive vehicles, the driveshaft (also called a propeller shaft) transfers power from the engine to the rear wheels.
If this driveshaft becomes bent or damaged, even slightly, it can throw off the balance of your drivetrain. This imbalance can cause the car to vibrate during acceleration, especially at lower speeds. As you drive faster, the vibration often becomes more intense and noticeable.
Driveshaft deformation can occur after hitting large potholes, debris, or during an accident. Once bent, it cannot usually be repaired – it must be replaced.
Solution:
If your car starts shaking after an accident or impact, have your driveshaft inspected. A replacement is the safest solution since repairing a bent driveshaft is unreliable and risky.
Bent Axle
Similar to the driveshaft, a bent axle can also cause noticeable vibration while accelerating. Even a minor collision with a curb or pothole can bend the axle slightly.
When the axle is bent, it disrupts the balance of rotation in your wheels, leading to vibrations that worsen as you speed up. In severe cases, this can also cause uneven tire wear and damage to the suspension system.
Solution:
Unfortunately, a bent axle cannot be repaired – it must be replaced. Continuing to drive with a bent axle can lead to unsafe driving conditions and further damage to other components, such as wheel bearings or the differential.
Old or Faulty Spark Plugs
Dirty or worn-out spark plugs can cause the engine to misfire, which may feel like a jerking or vibrating motion when accelerating. The spark plugs are responsible for igniting the fuel-air mixture in the engine’s cylinders.
When they become fouled with carbon deposits or oil, the spark becomes weak or inconsistent, leading to incomplete combustion. As a result, your car may vibrate or hesitate during acceleration.
This issue is more noticeable when idling but can also occur during driving. Poor fuel efficiency and rough engine performance are additional signs of bad spark plugs.
Solution:
Check and replace spark plugs regularly – typically every 30,000 to 60,000 miles, depending on your vehicle model. If they appear dark or coated with residue, it’s time for a replacement. Also, inspect spark plug wires and ignition coils to ensure the issue isn’t spreading further into the ignition system.
Unbalanced Tires
If your car shakes at certain speeds or during acceleration, your tires may be unbalanced.
When tires are mounted, their weight is not always distributed evenly. Tire shops use balancing machines to correct this by adding small weights to the rim. However, these weights can fall off over time, causing imbalance once again.
Unbalanced tires lead to vibrations that are often felt through the steering wheel or the entire cabin. The shaking tends to intensify at higher speeds as the tires rotate faster.
Other related issues include uneven tread wear and alignment problems, both of which can also cause vibration.
Solution:
Visit a tire shop to have your tires rebalanced and inspected for damage. Properly balanced tires ensure smooth acceleration, better fuel economy, and longer tire life.
Additional Causes of Car Shaking When Accelerating
While the above are the most common reasons, several other mechanical issues can also cause shaking:
- Worn CV joints: These joints connect the driveshaft to the wheels. If they wear out, you might feel vibrations during acceleration or turning.
- Warped brake rotors: While this issue typically causes shaking during braking, it can sometimes affect acceleration if the rotors are severely damaged.
- Clogged fuel injectors: Dirty injectors can cause inconsistent fuel flow, leading to engine hesitation or shaking.
- Transmission problems: If the transmission fluid is low or dirty, it can lead to uneven gear shifts, resulting in vibration during acceleration.
Preventing Car Vibration Problems
To keep your car running smoothly and prevent vibrations, follow these maintenance tips:
- Inspect tires regularly: Check for uneven tread wear, low pressure, or damage.
- Replace spark plugs on time: Clean or change them according to the manufacturer’s recommendation.
- Monitor your engine mounts: Have them inspected during routine servicing.
- Check your drivetrain components: Look out for unusual noises or vibrations when accelerating or turning.
- Schedule regular maintenance: Timely oil changes, fluid checks, and tune-ups can prevent most mechanical problems before they worsen.
Final Thoughts
A car that shakes when accelerating is a problem you shouldn’t ignore. It might start as a minor annoyance, but it could be a sign of worn-out components or more severe mechanical damage. Identifying the root cause early – whether it’s unbalanced tires, faulty spark plugs, or damaged drivetrain parts – can prevent costly repairs and keep you safe on the road.
Routine maintenance, regular inspections, and timely part replacements are the keys to ensuring your vehicle runs smoothly and efficiently. If you experience persistent shaking during acceleration, have your car inspected by a professional mechanic immediately to restore its performance and safety.
Frequently Asked Questions
This usually points to drivetrain issues like a bent axle, damaged driveshaft, or worn CV joints. It can also indicate unbalanced tires or faulty motor mounts that worsen under load.
Yes. Dirty or worn spark plugs can cause engine misfires, which lead to jerking or shaking while accelerating. Replacing spark plugs often solves this issue quickly.
No, it’s not advisable. Shaking can indicate serious problems with the drivetrain, suspension, or tires, which could worsen and lead to an accident or costly repairs if ignored.
The cost depends on the root cause. Replacing spark plugs might cost $100–$250, while fixing a bent axle or damaged driveshaft could range from $400–$1,200. Tire balancing costs around $50–$100.
Start by checking your tires and wheel balance. If the vibration persists, inspect the motor mounts, driveshaft, and spark plugs. A certified mechanic can perform a detailed diagnostic check using specialized equipment.
