Car Shakes When Accelerating But Not When Coasting (The Answer!)

It can be scary anytime that your car shakes, especially if it happens when you’re accelerating. This can make it difficult to navigate even the smoothest roads, and it’s also dangerous. So, what does it mean when your car shakes when accelerating but not when coasting?

It is a sign that your clutch or struts are bad if your car shakes when accelerating but not when coasting. This can also indicate that your drive shaft is bent, the axle is damaged, or your brake caliper is stuck. Otherwise, you can tell that your CV joints or wheel bearings are bad if your car shakes when accelerating.  

Even loose lug nuts can cause your car to shake while driving. Regular maintenance is important so that your car can drive smoothly. Follow along as we explore why your car shakes when accelerating but not when coasting.

Main Reason Your Car Is Shaking When Accelerating

Everything from a worn clutch to a bent drive shaft can explain why your car shakes when accelerating but not when coasting.

This can also indicate a problem with your tire alignment or even your brake caliper. Let’s take a look at the main reasons why your car shakes when accelerating but not when coasting.

Wheel Bearing Failure or Loose

Wheel bearings, much like lug nuts, are necessary for wheel and tire stability. Your car can shake while accelerating if your wheel bearings are loose because your tires won’t be lubricated. Tires are susceptible to friction with loose bearings, and you will experience a rough drive.

This problem is most likely localized to a single tire which is a good thing because it is expensive to replace wheel bearings. It costs up to $300-$400 to replace wheel bearings for a single wheel. Try not to drive through water and mud because that can easily loosen your wheel bearings.

Wheel bearings can also come loose if you drive over icy roads that are covered in salt. Otherwise, they can fail or become loose after roughly 100,000 miles, and you’ll need to replace them.

Worn Out Clutch

It is common for a car to shake when accelerating or even idling if the clutch is worn out. This only applies to cars with a manual transmission, and it is a common problem. Clutches are susceptible to damage from grease and oil contamination or rough handling.

Your clutch can also wear out if the disc or flywheel suffers damage. Clutches are supposed to last for the lifespan of your car, but that isn’t always the case. They can wear out in as little as 20,000 miles if you improperly shift gears or ride your clutch.

If your car shakes when accelerating, it may be because you keep your foot on the clutch pedal when you shouldn’t. It can cost up to $2,500 to replace your clutch.  

Defective Struts or Shocks

Struts and shocks are important parts of your car’s suspension system. If either part fails, your car will drive roughly and even shake when you accelerate. Your car’s suspension system helps absorb the shock as you drive so that your frame can stay steady.

However, your car can’t stay steady if your struts or shock absorbers are defective. The suspension system affects everything from your car’s speed to its stability. Your struts and shocks rely on oil to lubricate them so that you can drive smoothly.

The oil will dissipate when your struts and shocks overheat, and your ride will be rough. Dry struts and shocks are susceptible to damage and can wear out quickly. It costs up to $400 to replace each strut and shock, but it’s worth the cost.

Bad CV Joints

The CV joints in your car are important because they attach your wheels to your transmission. You will experience rough handling and shaking if your CV joints are bad. It is common to hear knocking sounds when your CV joints are bad as well.

Vibration and clicking sounds are also common signs that your CV joints are bad. You can find CV joints at both the front and back end of drive shafts in your vehicle. Unfortunately, CV joints are susceptible to damage from debris and moisture.

Mechanics charge up to $900 to replace CV joints, but you can do it without professional help for as little as $200.

Engine Mounts Are Worn Out

Your engine is held in the engine mounts, and your car will suffer several problems if they are worn out.

Up to 3 mounts hold your engine, and your car will shake when you accelerate if even one of them is damaged. Engine mounts last for an average of 6 years, but they can last for up to 10 years before you need to replace them.

They help to absorb shock and vibration that would rattle your engine. Without functioning mounts, your engine will bounce and shake as you drive which makes your ride uncomfortable.

It costs an average of $400 to replace engine mounts, but it varies based on where you go. This is considered a big job because it’s difficult to replace engine mounts, especially if you are inexperienced. That is why it’s worth the cost to hire a professional to replace your worn engine mounts.

Tires Aren’t Balanced or Unstable

Unbalanced and unstable tires can make your car shake while accelerating. Your car may not shake while coasting in this case, however. A car’s weight all rests on the tires, but they can only support the weight if your tires are balanced.

Tires naturally become unbalanced over time as you drive your car. This can also happen if you leave your car parked without moving it for a long time. Ideally, you should balance your tires every 7,000 miles or sooner if you notice your car shaking.

Unbalanced tires can lead to poor fuel efficiency because your engine has to work harder. You can expect to spend up to $200 to balance all 4 of your tires.  Shops typically charge $20-$50 per tire for balancing.

Lug Nuts That Are Not Properly Fastened

Your lug nuts need to be properly fastened or else your car will shake while accelerating. This is a common problem if you recently replaced at least one tire. Sometimes, technicians won’t tighten your lug nuts as well as they should, and this leads to problems.

This is a dangerous situation in some cases because your tire and wheel can fall off if your lug nuts are too loose. In some cases, this can also happen if your lug nuts are too tight. If you change your own tire, you need to make sure that your lug nuts are tight but not so tight that you can’t remove them.

It only costs $8 to replace a lug nut, and it’s worth the cost if your lug nuts are damaged. Otherwise, you can tighten your own lug nuts with a torque wrench.

Bent Drive Shaft

The drive shaft on your car is essential to evenly distribute torque throughout the vehicle. Drive shaft issues are considered serious because they directly affect your car’s ability to drive smoothly. Not only is this uncomfortable, but it can also be dangerous when you drive at high speeds.

Over time, a drive shaft can bend due to high mileage, frequent driving, and poor road conditions. This is unavoidable for many car owners. Once a drive shaft is bent, you cannot repair it and the only option is to replace it.

Typically, you will only need to replace your drive shaft once during your car’s lifespan. The average drive shaft can last for up to 75,000 miles. You can expect to spend up to $1,000 to replace your drive shaft.

Bent Axle

Axles connect your wheels and are essential for your car to drive smoothly. Unfortunately, axles experience plenty of stress during their lifespan which can cause them to bend. Axles are most likely to bend if you run over a curb or get into a car crash.

Even a simple pothole can damage and or bend your axle. This can also happen if you haul too heavy of a load than what your car is rated for. You can tell that your axle is damaged if your car shakes when accelerating but not when coasting.

Loud thumping sounds while accelerating can also indicate that your axle is bent. It typically costs at least $600 to repair axles because it is a difficult job. You can repair your own axle, but it’s quite difficult and professional autobody shops are best equipped to handle it.

Brake Caliper Is Stuck

A brake caliper is a critical part of your car’s brake system. It primarily controls your front brakes, and it contains your brake pads. This component can get stuck if there is a blockage in your brake line or if the piston seizes.

Brake calipers also help to control your wheels while you steer the car. That is why any obstruction in your brake caliper can cause your car to shake when accelerating but not when coasting. Your car will shake more and more the faster that you go if your brake caliper is stuck.

The only option is to replace your brake caliper if it’s stuck. It costs an average of $700 to replace your brake caliper, but it can cost up to $1,000.

Vacuum Leak

Your car will shake when you idle or accelerate if you have a vacuum leak. Another sign that your vacuum is to blame is that your wheel shakes while you drive. Vacuum leaks occur when your vacuum hose becomes disconnected.

The vacuum in your car is connected to the main intake manifold. It can come disconnected over time due to poor maintenance or driving over rough roads. A vacuum leak can also lead to other problems such as misfiring and difficulty starting your engine.

Luckily, this is a cheap problem to fix, and it should stop your car from shaking when you accelerate. It rarely costs more than $130 to fix a vacuum leak in your car.

Faulty or Dirty Spark Plugs

Spark plugs are essential to your car’s combustion system. Your car will struggle to run smoothly if your spark plugs are dirty or damaged, and your ride will be rough. Debris, dirt, sand, and fluid can negatively affect your spark plugs and even clog them.

This will disrupt the fuel and air mixture that is necessary for your engine to run smoothly. Car engines rely on a mixture of air and fuel or else your car will run too rich or lean. Spark plugs are quite durable, and you can typically resolve your problem if you clean them, but replacement is necessary in extreme cases.

You may never need to replace your spark plugs during the lifespan of your car. Spark plugs generally only need to be replaced after 75,000-100,000 miles, but you may need to clean them before that. You can expect to spend $80-$100 for a set of replacement spark plugs.

Proper Maintenance Is Important

The only way to ensure that you will always have a smooth ride is if you regularly maintain your car. Everything from your spark plugs and axle to your tire alignment can negatively affect your car if you ignore them. You should always get an oil change every 3,000 miles or your car’s performance will suffer.

It’s also important to take your car to a shop if you notice problems such as shaking upon acceleration. Bring your car to a shop if it shakes when accelerating but not when coasting. Professional technicians are equipped to fix problems with your axle, engine mount, CV joints, and drive shaft.

Ideally, you should set aside $100 or more per month for car maintenance. You never know when a key component of your car will fail and need to be replaced. Cars generally need some sort of service beyond an oil change after 10,000-12,000 miles. Pay attention to how your car feels while you drive it so that you know when you should bring it to a shop for maintenance.