Car Shakes When Accelerating But Not When Coasting- Cause, & Fixes

Feeling your car shake when accelerating can be a frustrating and concerning experience. It disrupts the smoothness of your ride and may signal underlying mechanical issues. Interestingly, if the shaking subsides while coasting, it provides a crucial clue about the problem.

This specific condition is typically linked to components that are active during acceleration, such as the drivetrain, tires, or engine. Understanding the root cause can help you avoid more significant problems down the road and ensure a safer, more comfortable drive.

In this detailed guide, we’ll explore the potential reasons behind this phenomenon, how to diagnose it, and steps to fix it. Whether you’re a car enthusiast or just someone looking for answers, this guide will provide actionable insights in simple and understandable language.

Common Causes of Shaking During Acceleration

There are several potential culprits when your car shakes while accelerating. These range from minor issues to more serious mechanical problems. Below, we break down the most common causes.

a) Tire-Related Issues

Unbalanced Tires: When tires are not balanced, they can cause vibrations that are especially noticeable during acceleration.
Worn Tires: Uneven tire wear or damaged tires may result in shaking as they fail to maintain proper grip.
Improper Tire Pressure: Overinflated or underinflated tires can lead to instability and vibrations.

b) Engine Problems

Misfiring Cylinders: A misfiring cylinder, caused by faulty spark plugs, ignition coils, or fuel injectors, can create a noticeable shake during acceleration.
Engine Mount Issues: Engine mounts secure the engine to the car’s frame. If they are worn or broken, the engine may shift excessively, leading to vibrations.

c) Transmission and Drivetrain Issues

Worn CV Joints: Constant velocity (CV) joints transfer power to the wheels. Damaged or worn CV joints can cause vibrations that intensify during acceleration.
Damaged Driveshaft: The driveshaft delivers power from the transmission to the wheels. If it is bent or imbalanced, it can result in shaking.
Transmission Issues: Problems within the transmission, such as worn gears or low transmission fluid, can also contribute to vibrations.

d) Suspension and Steering Components

Worn Suspension Parts: Damaged or worn-out suspension components like control arms, bushings, or struts can cause vibrations during acceleration.
Misaligned Wheels: Improper wheel alignment can result in uneven force distribution, leading to shaking.

e) Brake Problems

Although less common during acceleration, certain brake-related issues like warped rotors can cause vibrations that become noticeable when coasting or decelerating.

Diagnosing the Problem

Identifying the root cause of the shaking requires systematic observation and testing. Here’s how you can narrow it down:

Step 1: Observe the Conditions

Take note of when the shaking occurs (e.g., during acceleration, turning, or on certain road surfaces).
Pay attention to the intensity and frequency of the vibration.

Step 2: Inspect the Tires

Check tire pressure and adjust to the manufacturer’s recommendations.
Look for signs of uneven wear, bulges, or damage.

Step 3: Check Engine Components

Listen for unusual noises, such as knocking or sputtering, which may indicate engine misfires.
Inspect spark plugs and ignition coils for wear or damage.

Step 4: Test the Drivetrain

Perform a visual inspection of the CV joints and driveshaft for cracks, grease leaks, or misalignment.
Look for excessive play in the drivetrain components.

Step 5: Examine the Suspension

Inspect suspension parts for signs of wear or damage.
Check for proper alignment by visiting a professional mechanic.

Fixing the Problem

Once you’ve identified the root cause, the next step is to address it. Below are common fixes for the issues discussed earlier.

a) Tire Fixes

Balancing and Alignment: Take your car to a shop for tire balancing and wheel alignment.
Replacing Tires: If the tires are severely worn or damaged, replace them promptly.

b) Engine Repairs

Replace Spark Plugs or Ignition Coils: Faulty spark plugs and ignition coils should be replaced to prevent misfires.
Fix Engine Mounts: Replace worn engine mounts to stabilize the engine.

c) Drivetrain Solutions

Replace CV Joints: Damaged CV joints need to be replaced to ensure smooth power delivery.
Repair the Driveshaft: If the driveshaft is bent or imbalanced, it may require straightening or replacement.
Address Transmission Issues: Refill low transmission fluid or repair internal transmission components as necessary.

d) Suspension Adjustments

Replace Worn Parts: Install new bushings, control arms, or struts to stabilize the vehicle.
Realign the Wheels: Proper alignment can resolve uneven force distribution.

Preventative Maintenance

Preventing vibrations in the future requires regular upkeep. Here are some tips:

Rotate and balance tires every 6,000–8,000 miles.
Replace spark plugs and ignition components as per the manufacturer’s schedule.
Inspect and maintain drivetrain components during routine service visits.
Keep suspension parts in good condition by addressing wear promptly.

When to Seek Professional Help

While some fixes can be done at home, others require professional expertise. If you experience any of the following, consult a mechanic:

Persistent vibrations even after addressing obvious issues.
Unusual noises accompanying the shaking.
Difficulty controlling the vehicle.

Cost of Repairs

The cost of fixing a car that shakes during acceleration depends on the specific issue:

Tire Balancing/Alignment: $50–$150
Spark Plug Replacement: $100–$250
CV Joint Replacement: $200–$400 per axle
Driveshaft Repair: $300–$700
Engine Mount Replacement: $200–$600
Suspension Repairs: $300–$1,000

Investing in timely repairs can save you from more expensive fixes later.

Conclusion

A car that shakes when accelerating but not when coasting often signals an issue with the tires, engine, drivetrain, or suspension. Understanding the cause is key to resolving the problem and ensuring a smoother ride.

By following this guide, you can diagnose and fix the issue effectively, whether through DIY efforts or professional help. Regular maintenance is essential to prevent such problems and keep your car in optimal condition. If you’re ever in doubt, consulting a trusted mechanic is always the safest choice.

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Stephen Madison

Stephen Madison is a well-known automotive writer with over ten years of experience. A lifelong car lover, Stephen writes about cars in a way that is both easy to understand and exciting. At Vehicle Grip, Stephen writes about everything from car reviews to the latest automotive innovations. With a background in mechanical engineering, He has a deep knowledge of how cars work. This helps Madison explain complex car technology in simple terms that everyone can enjoy.