We look at the reasons why your car shakes when accelerating and what you can do about it.
Every car, no matter how reliable it is, will develop some sort of mechanical problem as it ages. Whether minor or severe, this problem can lead to symptoms that ultimately make your driving experience less pleasurable.
One of the biggest annoyances is vibration. Not only is it a pain to ride in a car that vibrates at constant speeds or during acceleration, but finding the exact cause of the vibration is often a hassle.
Fortunately, this issue is quite prevalent and the causes are well-documented. Keep reading for the various reasons a car vibrates when accelerating and what you can do about them.
IN THIS GUIDE
12 Reasons Your Car Shakes When Accelerating
Before I list the potential causes of the vibration, it must be noted that a car shaking when driving can often mean something different than if it vibrates when idling or braking. This guide mainly focuses on the former.
That out of the way, let’s go over the potential causes of your car’s vibration and the inspections you can undertake to identify and fix them.
Faulty CV Joint
Constant velocity joints (CV joints, for short) are part of a vehicle’s axles and are situated on both ends of the drive shafts. There are inner and outer CV joints, the former connecting the drive shafts to the transmission and the latter hooking the drive shafts with the wheels.
Although these components are designed to be durable and long-lasting, heavy damage to the plastic boots that protect them can cause water, dirt, and other substances to seep in and contaminate their lubrication, as well as cause the lubrication to leak.
The lack of proper lubrication leads to metal-on-metal contact, which in turn results in vibration under hard acceleration. This vibration intensifies as the damage worsens.
How To Fix
If a damaged CV joint boot is noticed early, simply replacing the boot and re-lubricating the CV joint is all that’s usually needed. This repair is fairly inexpensive, but a fair amount of labor will be involved.
On the other hand, if the CV joint itself is damaged, it cannot be repaired and should be replaced. Replacing a CV joint is a complicated affair, so you might want to seek the help of a professional.
Broken Motor Mounts
Also called engine mounts, motor mounts have one primary purpose: Hold the engine in place by attaching it to the car’s frame.
Their secondary purpose is to dampen engine vibration so that you and your passengers don’t feel the engine shake and vibrate as it operates
Not only will a damaged or broken engine mount cause everyone in the car to feel more vibration but, with the engine moving around more than normal, it can also result in the misalignment and even damage of other engine components.
How To Fix
You can stop the excess vibration by replacing the faulty motor mount.
You’d want to replace all the mounts even if just one is faulty. This is because, as one mount malfunctions, the others end up bearing more of the engine load, increasing their likelihood of failing prematurely.
Unbalanced Tires
Did you start noticing the shaking after you installed new tires? If so, unbalanced tires may be the culprit.
Tires never have identical weights all around when they are mounted on a wheel, so small wheel weights are attached to the rim at specific spots to balance them out.
A weight imbalance — even a slight one — will cause a small vibration whenever one or more of the tires rotate. The vibration becomes more pronounced as the car accelerates and the tires rotate faster, so pronounced that your steering wheel, floorboard, and/or your seat will also shake.
Sometimes, the imbalance is the result of one of the wheel weights simply falling off.
How To Fix
To fix unbalanced tires, your best bet is to take your car to a technician to have the tires rebalanced. You can perform the job yourself; however, it will require certain equipment that you probably don’t have on hand.
One such equipment is a tire balancer, a rather large, cumbersome, and fairly pricey machine that’s used to determine where on the rims the balancing weights should be placed to achieve perfect tire balance.
Underinflated Tires
Underinflated tires can also cause your vehicle to vibrate excessively when driving at high speeds.
When a tire becomes underinflated, its resonance frequency drops to a sub-optimal speed level that creates a noticeable shimmy whenever the vehicle is traveling at that speed.
Underinflation can also cause the tire to blow out, something you don’t want happening while driving.
How To Fix
Check your tire for flat spots or low pressure. If any of the tires are under-inflated, raising the pressure to match the manufacturer’s recommendations will raise the resonance frequency and cause the shaking or shimmy to disappear.
If you need a quality but affordable tire inflator or air compressor, check out the EPAuto Digital Tire Inflator And Air Compressor.
Bent Rims
Another wheel-related issue that can cause your car to shake is bent rims.
When a rim is bent, it will cause the tire to make uneven contact with the ground, resulting in a rougher and shakier ride that transmits vibration up the steering column.
Vibration at the front of the car is indicative of a bent front rim, while shakiness in the seat or farther behind the vehicle is a good sign that a rear rim is bent.
How To Fix
Whether or not a bent rim can be repaired will depend on the severity of the damage and the type of wheel your car has. If dealing with steel wheels and the bent is the only issue, the affected wheel can usually be repaired, though you probably won’t want to do it yourself.
Repairing a bent rim requires a lot of effort and possibly a very large hammer, so it’s probably best to let a training automotive technician handle it.
On the other hand, it’s inadvisable to repair a bent rim if you have alloy wheels. Attempting to repair even minor bends can cause the rim to crack, so the best bet is usually to have the wheel replaced entirely.
Loose Lug Nuts
This simple and common problem can be quite catastrophic if not addressed quickly.
Lug nuts help attach the wheels to your car. If they become loose as a result of not being properly torqued down, the wheel will develop a slight wobble that would make the car seem like it’s shaking as you drive.
Left untightened, the lugs can loosen so much that the wheel itself might actually fall off while you’re driving. You don’t want that happening, do you?
How To Fix
It’s critically important that you fix this issue once you notice it. Fortunately, fixing loose lug nuts is easier and cheaper than balancing your tires or repairing a bent rim.
All you need to do is use a torque wrench to tighten the loose lug nut to its proper factor specs.
If you need a torque wrench and are looking for one, the PAuto Drive Click Torque Wrench is a great value. Using a regular lug nut wrench or tire iron will also suffice.
Stuck Brake Caliper
A seized or stuck brake caliper can cause your car to vibrate while it’s in motion.
If one or more of the brakes are being constantly applied, you will notice the steering wheel vibrate at around the 40-50 mph (64-80 km/h) mark, with the vibration getting worse as you reach even higher speeds.
You will likely also notice a burning odor emanating from the vehicle once it comes to a stop.
How To Fix
If you suspect that the vibration is caused by a stuck brake caliper, smelling each wheel for a burning odor should allow you to detect which brake calipers are at fault.
The caliper bolts, piston, and slides are common problem areas, but inspect the entire brake system to make sure.
Simply cleaning and lubricating the afflicted brake parts is sometimes all that’s needed to get them working properly again. However, failed components should be replaced.
Bad Spark Plugs
A shaky engine is one of the various symptoms of dirty or fouled spark plugs or glow plugs, in the case of diesel engines.
When your spark plugs are dirty or worn, they struggle to create the spark needed by your engine to efficiently carry out the combustion process, possibly causing it to misfire.
While you’re more likely to notice the problem when at a stop, engine misfires can cause your car to jitter or vibrate when driving.
How To Fix
The solution here is to clean or replace the spark plugs, which is typically not expensive to do. Spark plugs are very cheap (see for yourself), and you don’t need to be a mechanic to install them.
If you remove one spark plug and notice an excessive amount of a black, feathery deposit on the tip, chances are the other plugs have also gone bad and need to be replaced, as well.
Bent Driveshaft
If your car has a rear-wheel drive (RWD) setup, the vibration may be caused by a bent driveshaft.
With RWD vehicles, power from the engine gets delivered to the rear axle and wheels via the driveshaft. Should the driveshaft become bent or damaged, even if slightly, the vehicle is likely to shake when accelerating at low or high speeds.
How To Fix
A damaged or bent driveshaft is usually very difficult, if not impossible, to repair and isn’t a job for the average person. Chances are you will need to replace the entire unit.
Bent Axle
Accidentally driving over large curbs, potholes, and the such or being involved in a minor collision can do a number on a vehicle even if there are no obvious signs of damage. Such occurrences can cause an axle to get bent, a serious issue if ever there was one.
A bent axle will typically cause your car or truck to be unstable, shaky, and noisy, conditions that worsen as you accelerate.
A bent or otherwise damaged axle can also lead to other components of your car such as the CV joints getting damaged, exacerbating the vibration and resulting in very costly repairs.
Worse yet, you won’t be able to control your car if an axle breaks while driving, which can have catastrophic consequences for you and your car.
How To Fix
Suffice to say, a bent axle is one issue you can’t afford to ignore or take lightly. Unfortunately, as with a bent driveshaft, it can’t be repaired in most cases and must be replaced.
You’re going to need help with the replacement, so get in touch with your mechanic.
Vacuum Hose Issues
If a vacuum hose disconnects or develops a tear that causes air to leak, the decreased air pressure can induce one or more of the vehicle’s sensors to become confused, leading to misfires, backfires, loss of power, and other issues that make the engine run rough.
Of course, a rough engine can cause your car to vibrate when idling or accelerating.
How To Fix
You will need to inspect all hoses to make sure they are properly connected and free of tears or cracks. Use a small clamp to tighten any hose that has become loose.
Turbocharged cars have vacuum hoses that are particularly prone to disconnecting. A common solution is to replace them with stronger silicone hoses.
Steering Wheel Issues
The steering system can cause your car to vibrate in several ways.
First, if your steering wheel operates properly when you drive straight but shakes when you turn, the problem likely has to do with worn or damaged tie rod ends. If it shakes when driving straight but not when turning, it’s the ball joints that may be the issue.
Sometimes, the steering wheel shudder is the byproduct of low power steering fluid, which deprives the power steering rack and pump of the pressure they need to function properly.
How To Fix
Inspect the tie rod ends and ball joints for wear and tear. Inspecting and repairing the former is something just about anyone can do with a few basic tools and a little bit of know-how, but it involves jacking up the car.
The same can’t be said about ball joints, which are very tricky to access and install.
Also check that your power steering isn’t leaking and that the power steering fluid is at an optimal level. Unfortunately, a leaking steering rack usually can’t be repaired and must be replaced.
You might want to save yourself the trouble by getting in touch with your mechanic once you notice any of these issues.
Shaking Car FAQs
We knew that inquisitive readers such as yourself would have more questions, so we took the liberty to answer some other popular questions about the topic.
Is It Normal For A Car To Shake A Little?
Yes, it’s normal for vehicles with an internal combustion engine to vibrate slightly when driving due to the rotation of the transmission gears, crankshaft, and other moving parts in the engine. The vibration is less pronounced in electric vehicles, which have simpler propulsion systems.
However, when this gentle or “normal” vibration turns into shaking, your car or truck likely has an issue that needs to be investigated and addressed.
Is It Safe To Drive When Your Car Is Shaking?
The reason your car vibrates when accelerating at low or high speeds could be completely harmless or it could make the car dangerous to have on the road, but you won’t ever know without diagnosing the underlying problem.
Either way, you shouldn’t ignore the vibration. Issues such as a bent tire, axle, or driveshaft can make it difficult to control your vehicle at highway speeds, increasing the risk of a collision.
Even if the issue is unlikely to cause an accident, it can develop into a more serious and expensive problem if not promptly addressed.
Why Does My Car Vibrate When I Press The Gas Pedal?
This could be due to engine misfires, which in turn may be caused by a faulty spark plug or fuel system. Misfires will make an engine shake under acceleration.
Check that the spark plugs are delivering a proper spark. If the ignition system isn’t the issue, inspect the fuel system for the correct fuel pressure and make sure the ducts and filter in your air intake are clean.
Can transmission Cause A Car To Shake?
Yes. A transmission will shift hard, shake, or shudder during shifting if it’s damaged, worn, or poorly lubricated, sending vibration throughout the vehicle, as a result.
One way to tell if the shaking is due to a transmission problem is if the Check Engine Light (CEL) comes on when your car or truck begins to vibrate during acceleration
Final Thoughts
Having your car vibrate while you drive is one of the most annoying things you will ever experience as a motorist. Granted the shaking could be due to a myriad of issues with the vehicle, rest assured that there is something you can do about it.
In this article, we presented a host of likely reasons why your car vibrates when accelerating, as well as what can be done to fix each issue. While you may be able to repair some of them yourself, many are best left to a professional.
Either way, it’s crucial that you identify and address the underlying issues immediately so that they don’t snowball into more expensive repairs down the line. Don’t wait or procrastinate!
Now that you know why your car shakes when accelerating, you might also want to check out our other car care articles. We recently wrote an informative piece on repairing a sagging headliner, the various causes of metal shavings in oil, and even why indicator lights only work sometimes.