Home Auto Car Shakes When Accelerating but Not When Coasting: 7 Causes and Solutions

Car Shakes When Accelerating but Not When Coasting: 7 Causes and Solutions

by Maria L. Searle
Car Shakes When Accelerating but Not When Coasting 7 Causes and Solutions

Sensing unusual vibrations while driving your car can be confusing and frustrating at the same time. At first, you may be tempted to ignore the situation and hope that it resolves on its own. 

This isn’t the best idea, as small issues with your car can worsen over time, causing bigger damage, more expenses, and serious risks to your health and safety in the long run.

So, what do you do if you notice that your car shakes when accelerating but not when coasting? 

To help you answer this question, we’ve put together a list of possible reasons behind your car’s shaking sensation, including their corresponding solutions. Let’s get started!

1. Damaged Inner CV Joint

Your car’s constant velocity joints, or CV joints, are a vital link between the transmission and wheels. If you have a front-wheel drive car, you’ll find CV joints on both ends of the drive shafts. Note that cars have both inner and outer CV joints.

A tear in the joint boot that protects a CV joint will allow water and dirt to get inside and contaminate the joint’s lubrication, ultimately resulting in joint damage.

A damaged inner CV joint can cause even the tiniest car vibrations to turn into violent shaking, especially during hard acceleration. You’ll need to replace the faulty joint to fix the problem.

2. Dirty or Worn Out Spark Plugs

As their name implies, spark plugs deliver the quick jolt of electricity that you need to start your car and keep it running. Spark plugs can get clogged, dirty, and worn out over time, causing your engine to misfire and the vehicle to shake.

You’ll likely notice the shaking every time you stop or accelerate your car. But when you take your foot off the gas pedal and coast, the shaking usually goes away. That’s because your engine’s cylinders don’t fire whenever you’re coasting.

One way to confirm this is to remove one of your spark plugs and inspect for dirt buildup on the tip. To fix the issue, you’ll either need to clean your spark plugs or replace them entirely.

3. Bent or Damaged Axle

Bent or Damaged Axle

Another common reason behind your car’s shaking during acceleration is a bent axle. This usually happens due to an accident involving a massive force, such as hitting a curb or a large rock. Rough usage and gradual wear and tear can also lead to a damaged axle.

To stop the shaking and avoid further damage, have a trusted mechanic inspect your axle for bends and replace the axle if necessary. If you have a rear-wheel drive car, you might want to check your driveshaft for damage as well.

Your driveshaft is responsible for sending power from your engine and transmission to the rear wheels, and any issues with this component can also result in wobbling during acceleration.

4. Faulty Motor Mount

The purpose of motor mounts is to secure your engine to the vehicle frame. They also dampen the engine’s vibrations so that the people inside the car don’t feel as much shaking when it’s running.

Motor mounts are made of a hard rubber material that’s perfect for absorbing shocks. However, a defective or broken motor mount won’t be able to do its job well, resulting in the engine rattling during acceleration and strong vibrations throughout the car. 

It’ll also cause a strain on other motor mounts since they’ll have to bear more load. If the motor mount fails to hold the engine in place, other car parts are at risk of misaligning or breaking off as well. A timely repair or replacement will resolve this.

5. Unbalanced Tires

Did you know that even a small weight imbalance or slight unevenness in your tires can cause vibrations every time a tire rotates? The vibrations only become stronger every time you speed up, resulting in a loss of stability that’s dangerous to you and your passengers.

Possible reasons behind unbalanced tires include uneven wear, problems with tire pressure, or having new tires installed on your car. Another possibility is that one of your adhesive wheel weights fell off, resulting in a loss of balance. 

A quick fix would be to take your car to your service center and ask them to rebalance the tires. If the issue is crooked or misaligned tires, then you’ll need a tire alignment.

6. Loose Wheel Bearings or Lug Nuts

Wheel bearings have the important job of ensuring that your wheels run smoothly without unnecessary friction to slow them down. Bearings can loosen or break, causing the wheels to move out of their axis and your car to shake when running at high speed.

On the other hand, lug nuts are small circular metal parts that connect the hub of each wheel to the axle. Lug nuts that aren’t properly torqued to the hub and have become loose over time will cause your wheels to wobble and your car to shake while driving.

You’ll need to have a damaged wheel bearing replaced by your mechanic, while a loose wheel bearing requires tightening. Loose lug nuts can be tightened with a torque wrench. Ensure that you’re using the right size lug nuts, as the wrong size can cause more issues.

7. Stuck Brake Calipers

It’s possible for malfunctioning brake calipers to get stuck or jammed, causing your steering wheel to shake when you reach 40 to 50 miles per hour. As you accelerate to higher speeds, the vibrations tend to get worse. 

You may also smell a burning odor coming from your car when you come to a stop. To fix this issue, your mechanic will inspect your brake system, including the caliper bolts, slides, and pistons. 

Failed brake components will require replacement, but in some cases, a cleanup and lubrication are all that you’ll need.

Wrapping Up

Although a shaking car can be caused by a simple problem like a loose lug nut or a dirty spark plug, it can also be the result of a more serious issue, such as a malfunctioning brake system.

It’s best to have unusual vibrations checked by a trusted mechanic as soon as possible. Not only will they be able to accurately pinpoint the issue, but they’ll also have the proper tools, expertise, and experience to correctly address it.

Remember, the sooner you resolve the shaking, the better it will be for the state of your vehicle and the safety of the people in it.

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