It’s easy to get stressed out when your car shakes when accelerating. Unfortunately, this problem is bound to happen, especial if you have an older car – and many drivers are going to be totally unaware of what their car is trying to tell them while it shakes after they accelerate.
I myself have stumbled across this situation long before i was a mechanic, and didn’t know what to do. So, I’ve gathered everything you need to know to quickly diagnose and fix the common cause of your vehicle shaking when you press down on the gas pedal.
In short, almost a dozen different problems can cause your car to shake when you accelerate. These issues range from bent axles to loose lugs, to tie rod or transmission problems. Let’s dig a little deeper, shall we?
- 1. Bad Inner/Outer Tie Rods
- 2. Unbalanced/Uneven Tires
- 3. Damaged Inner CV Joint
- 4. Worn Universal Joint
- 5. Bad Motor/Transmission Mounts
- 6. Torn or Disconnected Vacuum Hose
- 7. Poorly Attached Wheel
- 8. Bent Driveshaft
- 9. Brake Caliper Is Sticking
- 10. Bad CV Axle
Common Causes of a Car Shaking When It Accelerates
There could be many causes of car shaking when accelerating. Some of them could be minor causes, like a bad attached wheel, unbalanced tires and a disconnected vacuum hose. But others, like a bent driveshaft, bad inner/outer tie rods, bad motor mounts, etc, could require a hefty repair.
I have compiled a list of all the possible causes of car shaking when accelerating from most likely, to least likely (but make sure to check each one as every car could have a different case), as well as provide information on how to fix it, and how it fails:
1. Bad Inner/Outer Tie Rods
Your tie rods connect both of your front wheels to your suspension system, allowing you to steer your vehicle in the first place but also helping to dampen all the motion while you are driving on everything from pavement to gravel roads (and anything off the beaten path, too).
If your inner or outer tie rods begin to wear out, you’re going to start to notice a lot of extra vibration – especially if your driving at low speeds, or when trying to accelerate from a dead stop. You would usually feel those vibrations in the steering wheel, and it might even feel unresponsive
You’ll probably also notice a clunking or knocking sound when you make a turn, which is especially pronounced at slow speeds. This means that the tie rods are starting to give and will need to be replaced straightaway.
Inner/outer tie rods can be tricky to replace yourself, but it is definitely doable, as shown in this video:
2. Unbalanced/Uneven Tires
Most of the time, you’ll notice unbalanced or uneven tire shaking after you’ve swapped out at least one of your tires for a brand-new one.
Maybe you had a flat, maybe you have uneven wear, or maybe you’re just replacing two wheels at a time (the minimum you should swap out at once, specifically to avoid this problem) because that’s what your budget allows.
When your tires are unbalanced or uneven (uneven meaning incorrectly mounted on the wheel) the weight is going to be off just a little bit. You’ll notice minor shaking and vibration at slower speeds that get worse and worse as you accelerate, sometimes to the point where your car is shaking violently.
Swing by the tire shop if you notice this and have them balanced or remount your tires properly. That should clear everything up for you.
Related: Should I Balance My Tires Before An Alignment?
3. Damaged Inner CV Joint
Another core component of your axle and your steering system are the CV joints that sit at the ends of both axles.
If the inner CV joint starts to wear out, you’ll notice a little bit of vibration while you are driving around town, which can turn into very strong vibrations as you accelerate – especially if you accelerate quickly
Most of the time, this damage is caused by a tear in the CV boot that wraps around the CV joint itself. Dirt, gunk, grime, and anything else can work its way into that joint and degrade it over time.
You’ll end up with pure metal to metal contact that leads to friction and failure, and that’s when the vibration really starts to get bad.
If you have an aftermarket CV Axle, it likely won’t be built to the same standard as the OEM ones-especially if you want to cheap out. Which may be the cause of car shaking when accelerating. Why, you might ask? Because aftermarket CV axles can have bad CV joints which don’t effectively dampen the harshness and the vibrations from driving, and because of that, the vibration will instead be transferred to other car parts, making your car shake when accelerating. This is usually felt inside the cabin.
Since you can’t replace the CV joint itself, you would have to replace the whole CV Axle. It can be rather difficult, so if you are unsure, it’s better to visit a mechanic. But you can still try:
4. Worn Universal Joint
Universal joints (sometimes just called “u joints”) are critical components of your driveshaft, typically found on rear wheel drive vehicles, four-wheel-drive trucks and SUVs, and vehicles designed for life off of the paved road.
They are specifically designed to help your driveshaft handle any potential misalignment from uneven road surfaces. If your universal joint starts to wear unevenly – or starts to degrade – you’re going to start to feel some vibration while accelerating.
These joints need to be swapped out straightaway. Any delay can cause the u joints to start wreaking havoc on other parts of your vehicle (such as your transmission), which can be very costly.
5. Bad Motor/Transmission Mounts
The mounts are specifically designed to hold your motor and transmission in place as your motor and your transmission (to a lesser degree) are going to want to bounce all over the place when you are driving your vehicle. That’s just how they operate, you can’t cancel that, but you sure can dampen it.
Motor and transmission mounts keep these pieces of sophisticated machinery in place, but are also designed to dampen the kind of vibration you would have otherwise inevitably felt from all of the tiny explosions happening inside these components.
If your motor mount or transmission mount have busted (or are just degrading) you’ll probably start to feel a little bit of extra vibration than you are used to. This increases at higher speeds as your components work harder and harder, but you should feel a bit of vibration at a standstill with the engine on, too.
Related: Can You Drive With Bad Motor Mounts?
6. Torn or Disconnected Vacuum Hose
A relatively common issue that can cause car shakes when accelerating that get pretty violent really quickly. Even just a tiny tear in your vacuum hose can cause big problems.
When your vacuum hose becomes compromised or loose, the air pressure in your engine is going to go all out of whack. That’s going to cause a ripple effect across each of the numerous sensors in your vehicle, creating backfire problems, loss of power problems, and an engine that runs anything but smoothly.
Inspect your hoses, make sure they are where they are supposed to be, and double confirm that they are in good condition. Anything that looks like it should be replaced definitely needs to be, though this is (usually) a pretty inexpensive fix.
7. Poorly Attached Wheel
Believe it or not, loose lug nuts are a much more dangerous problem than most people realize.
Lug nuts that have not been properly torqued down on the wheel hub inevitably work themselves loose over time, and that allows your wheels to wiggle and wobble as you drive down the road.
Given enough time, though, those lug nuts will work themselves clear off of the lug itself – and that’s when your wheel is most likely to come flying off of your vehicle
Confirming loose lug nuts are the reason that your car is shaking while accelerating is pretty simple and straightforward. Simply try to twist them with your fingers alone and see how tight or loose they are.
It’s not a bad idea to slap a torque wrench on each lug nut and make sure that it is torqued correctly, either.
This will help guarantee that your lug nuts stay in place (and that your wheel does, too).
8. Bent Driveshaft
Rear wheel drive vehicles (and all-wheel-drive vehicles) are going to have a driveshaft that pushes power from the engine all the way back to the rear axle.
Driveshaft damage (especially a bent driveshaft) is usually a result of an accident and not wear and tear. You’ll start to notice shaking at lower speeds that gets worse and worse as you accelerate.
Unfortunately, this is a component you can’t bend back into shape. If your driveshaft is causing shaking while you accelerate you’ll need to swap it out for a new one.
9. Brake Caliper Is Sticking
Breaking systems on all vehicles need to be kept up and maintained just like everything else.
Mainly, the piston inside the brake caliper is sticking because the slide pins have lost lubrication, preventing proper engagement and disengagement of the brake pads. Sometimes all you have to do to fix it is to clean and lubricate your caliper to get it back to brand-new condition.
If you have a caliper that is sticking even just a little bit you’ll usually start to notice some shaking and some vibration between 40 miles an hour and 50 miles an hour or so. Speed up even faster and the shaking generally gets worse, and eventually you’ll start to smell something burning – your brakes!
Uneven Wear On Brake Rotor/Pads
When your caliper is sticking, it will quickly wear out the brake rotor/pads, which could make them uneven. So if you didn’t feel vibrations when accelerating, you would definitely feel vibration when pressing on the brake pedal.
In more extreme situations, though, your brake system may have to be replaced (not just the caliper, but the brake lines themselves). This is a great time to swap out your pads, too.
10. Bad CV Axle
Your axles connect your wheels together, and are perfectly straight, which gives you stability and control when you drive your vehicle down the road.
At the same time, it really doesn’t take a whole lot to bend your axle, even just a little bit – which can be enough to throw the balance of your vehicle all out of whack. Like smacking into a curb, bumping over a big rock, or even just being involved in a minor fender bender, which can cause your vehicle to shake, rattle, and roll as you accelerate.
Some CV Axle’s have a thing called “Dynamic Damper” which is a weight that sits in the middle of the axle, and when it becomes misaligned, it can cause vibrations and shaking when accelerating, even if the the whole CV axle and joints are completely fine.
The only way to fix any of those issues is to swap out the axle completely, something you’ll want to do ASAP.
Is It Safe To Drive When Your Car Is Shaking?
It depends what issue is causing your car to shake, but generally, it is not safe to drive a car when it is shaking as it compromises the stability of your vehicle, which puts you at risk of a crash. It is better not to test your luck and figure out what’s causing your car to shake in the first place before proceeding to drive. But a short trip should be fine.