11 Reasons Why Your Car Shakes When You Accelerate and How to Fix It
Does your car shake or vibrate when you accelerate? This symptom, although simple, can often indicate a serious problem. Let’s look at the most common reasons why your car shakes when accelerating and how to isolate the problem and finally fix it.
Common Causes of Car Vibration When Accelerating
Note: A car that shakes while driving often means something completely different than a car that shakes when stopping or braking. So, be aware when the wobble occurs. A car that shakes when accelerating can not only be frustrating, but it can also be dangerous. Here are some possible causes for your car shaking:
1) Damaged inner constant velocity joint
Constant velocity joints are located at the end of each axle. There are both outer and inner joints. When the inner CV joints become damaged or start to fail, you’ll notice your car vibrating under hard acceleration. When it gets worse, a slight vibration under load turns into a violent shudder.
Damaged constant velocity joints are usually caused by cracks in the lining of the joint. This allows water and debris to get inside the bellows and contaminate the grease that protects the internal splines. Without proper lubrication, metal-to-metal contact eventually leads to failure. The only solution is to replace the entire CV joint or CV axle.
2) Faulty Motor Mounts
The primary purpose of an engine mount is to secure the car engine to the vehicle frame. The secondary purpose is to dampen or reduce engine vibrations so that the car’s occupants don’t feel the constant rocking and pulsating of the engine while driving. Engine mounts are made of a hard rubber material that absorbs this vibration.
If an engine mount is damaged or broken, not only will you feel excessive vibration inside your car, but because the engine is not mounted in the correct position, other parts of the engine may become misaligned and eventually break.
You’ll feel a bad engine mount when idling, but the shaking may be more noticeable when accelerating as the engine is under force. Replacing the bad engine mount should stop the vibration. Keep in mind that if the engine mount is defective, it puts more strain on the other bearings, making them more likely to fail.
3) Your tyres are out of balance
If you’ve recently fitted new tyres and have noticed your car shaking while driving, it could be because your tyres are out of balance. When a tyre is mounted on a rim, it’s never the same weight everywhere.
To fix this, a tyre fitter will mount the tyre and wheel assembly on a balancing machine and glue small wheel weights in specific locations on the rim to achieve perfect balance. As the tyre rotates, the slightest weight imbalance will result in small vibrations.
At higher speeds, where the tyres are rotating very quickly, the vibrations will be more noticeable and you’ll actually feel your steering wheel shudder. If your car vibrates at a certain speed and gets worse at higher speeds, your tires may be out of balance. It’s also possible that one of the adhesive wheel weights has simply come off. To fix this problem, take your car back to a tire dealer and have your tires rebalanced.
4) Loose Wheel Nuts
A simple problem (more common than you’d think) that can have disastrous consequences. If the wheel lug nuts aren’t properly tightened on the hub and some of them loosen over time, your wheels will wobble slightly. Your car will appear to be shaking while you’re driving.
If lug nuts aren’t tightened, they can come completely loose over time and actually cause the wheel to fall off while you’re driving. You definitely don’t want that. Also, remember to use the correct size lug nuts.
To ensure that your lug nuts aren’t loose, use a torque wrench to make sure each lug nut is tightened to the correct factory specifications. If you don’t have a torque wrench, you can use a regular lug nut wrench or a tire iron to tighten them.
5) Bent Driveshaft
If your car is rear-wheel drive (RWD), power is transferred from the engine through the driveshaft (or propeller shaft) to the rear axle and connected wheels.
So if the driveshaft is even slightly bent or damaged (often due to an accident), it will cause your car to shake when accelerating at low speeds and even worse at higher speeds. Driveshafts usually can’t be repaired, so replacement is your only option.
6) Bent Axle
If you accidentally drove over a curb or a large rock or had a minor accident, don’t think that just because you don’t see any visible damage, you’re okay. The accident could have bent your axle, and things are serious. You will feel a vibration coming from the car, and it will get worse as you accelerate. Like drive shafts, bent axles need to be replaced immediately, or further damage may occur.
7) Stuck Brake Caliper
If the brake caliper on a wheel is faulty and causing it to stick, then it can cause brake shudder and other car vibrations. In this particular situation, the steering wheel will be what vibrates as you reach about 40-50 miles per hour.
The vibrations will get worse as you continue to accelerate at higher speeds. When you come to a stop, you will likely notice a burning-like odor coming from the vehicle.
If you suspect a stuck brake caliper, you should be able to figure out which wheel it’s at using your nose due to the smell. You will need to inspect all parts of the brake system there paying particular attention to the caliper bolts, slides, and piston. Sometimes cleaning and re-lubricating the parts is all that’s needed but failed brake components will need to be replaced.
8) Torn or Disconnected Vacuum Hose
This common problem can cause severe shaking or shuttering of a car while driving. If a vacuum hose becomes disconnected or develops an air leak due to a small tear, the lack of air pressure can cause various sensors to get confused which in turn can lead to misfires, backfires, losing power, and other problems where the engine doesn’t run smoothly.
Inspect all hoses to make sure they are connected to somewhere and they have not tears or cracks in them. You may need to use a small clamp to reattach hoses that are too loose on the fitting.
Vacuum hoses on turbocharged cars are even more prone to disconnecting. Replacing with stronger silicone hoses is commonly done as a permanent solution.
9) Dirty or Worn Spark Plugs
Spark plugs that are dirty or fouled up can cause the engine to misfire. While the problem is usually first noticed when at a stop, it may also make it seem like the car is vibrating when driving. If you don’t remember the last time you replaced your spark plugs, it may be time to do so.
10) Suspension Issues
The suspension system of your car is responsible for keeping the wheels in contact with the road, providing a smooth ride, and absorbing shocks. If there’s a problem with your suspension system, you may experience shaking or vibrations when you step on the gas. Some common suspension problems that can cause your car to shake and vibrate include:
Worn Ball Joints – These are the pivot points between the suspension and the wheels. If they wear out, they can often cause your car to shake.
Worn Wheel Bearings – These are the bearings that allow your wheels to rotate smoothly. With bad wheel bearings, your car will definitely start to shake, especially at higher speeds.
Damaged Shocks or Struts – These are the components that absorb shocks and keep your car stable. If they are damaged or worn out, expect your vehicle to shake.
11) Death Wobble
Death wobble is a violent shaking of a vehicle’s front end that can be caused by worn-out steering or suspension parts, improper tire inflation, or other issues. It affects various types of vehicles, most notably trucks, SUVs, and Jeeps.
If you experience death wobble while driving, it’s important to slow down and pull over to avoid a potential accident. A mechanic can diagnose the issue and provide a solution to get your vehicle back to safe driving condition.
How to Diagnose Car Shaking
Here are some steps you can take:
Visual Inspection
The first step is to visually inspect the vehicle. Check for any visible damage or wear on the tires, suspension, and steering components. Look for any loose or broken parts, and check for leaks or other signs of damage under the hood.
Test Drive
Once you’ve completed a visual inspection, take the vehicle for a test drive. Pay attention to the type of shaking you’re experiencing, as well as the speed and intensity of the vibration.
Is it come from the front or rear of the vehicle? Is it more noticeable at low speeds or high speeds? Does the shaking increase in intensity as you accelerate? Does your vehicle only shake and vibrate on certain roads? All of these questions can help you (or your mechanic) find the root cause.
Computer Diagnostics
If you’re unable to determine the cause of the shaking through a visual inspection or test drive, it may be necessary to use computer diagnostics to pinpoint the issue. A mechanic can use a diagnostic tool to read codes stored in the vehicle’s computer system and identify any potential issues.