Reasons Why Your Car Vibrates Between 30 mph, 40 mph, and 60 mph

Shuddering of the car past 30 miles per hour is very alarming and a problem you should identify as soon as possible. It might not seem important, but prolonged vibrations will certainly lead to increased parts wear and failure that can even cause a loss of control over the vehicle.

You need to prevent this from happening, so read the following list and identify the cause before an accident occurs. To make the most comprehensive list, I’ll include all possible causes for car vibration, shaking, shuddering, or unusual noises.

1. Tires

A problem with tires can manifest through vibrations inside the passenger cabin, and there’s a number of causes.

Tire wear

Uneven or complete tire deterioration is one of the primary suspects. Tires can only last so many years or miles before requiring a replacement. To measure the tread of your tires, you’ll need a micrometer caliper.

In short, you’ll use the protruding spike at the bottom of the caliper as a depth measuring device. Calibrate and adjust the measuring mode on the digital display, then let the spike plummet inside the tire tread. Tires with a tread depth of under 4mm or 0.15 inches are not considered safe for the road.

You might not be able to see it, but your tires can slant slightly towards or away from the vehicle, causing uneven wear on one side. Measure the tread depth across the width of the tire to see if there’s any discrepancy.

Winter tires

Winter tires also cause unnecessary vibrations, because their rubber isn’t designed to perform well in warmer seasons. Check the side of the tire for a snowflake symbol or M+S marking which signifies that it’s a winter tire. You can continue driving on them, but be aware that winter tires perform worse during summer, wear out more quickly, and are much less comfortable to ride on.

Unbalanced tires

Because neither the tire nor the rim is absolutely perfect, combining two objects of such size will form a slight unbalance, which is enough to cause the steering wheel and the floor to vibrate.

Balancing should always be done when installing tires on a rim, if the tire goes flat, crosses a lot of miles, or simply starts causing vibrations. Tire technicians use special machines to determine the points of unbalance and clip wheel weights to the edge of the rim to straighten it. Try to remember when’s the last time you’ve balanced your tires, or take your vehicle for an inspection at the local tire shop.

2. Wheels

Balancing tires and tire alignment are erroneously considered to be the same thing. Whereas balancing the tires has to do with their geometry on the rim, tire alignment has to do with the angle of the wheel itself.

Misaligned wheels wear down tires more quickly, cause reduced stability and control, and finally rattling or vibrations you’re experiencing. Wheel alignment is a task for a professional, as it requires specialized tools and expertise.

A very dangerous yet common cause for violent rattling is improperly tightened wheel bolts. If you suspect it to be the cause, stop immediately, take out the tire wrench from the truck and see if any of the wheel bolts can be tightened. You should also check the rims for bends, chips, and cracks that can cause unbalanced rotation and result in vibrations.

3. Brakes

Car brakes rely on friction to stop the vehicle. When you press on the brake pedal, a hydraulic pump pushes oil towards the caliper, where a caliper piston compresses brake pads against the disc.

Try to listen for a sound that accompanies the vibrations. It usually happens right after you’ve pressed the brake, and especially in the 30 to 40 mph zone as you decelerate from higher speeds.

Changing brake pads or the brake disc is a fairly difficult task that involves proper procedure and careful handling of the brake pipes. The most difficult part is airing out the brake system – do this incorrectly, and an air bubble will sabotage the brakes right when you need them. However, you can save some money by inspecting the brakes yourself, as it’s a relatively simple task.

4. Suspension

Suspension is composed of many parts that work together to absorb the bumps and imperfections on the road. It’s also responsible for handling and stability of the vehicle. When one or more components fail, vibrations at 40 mph become common.

Worn components

Suspension wears out just like any other component. Vibrations it has to absorb, moisture, rust, and age affect how well the suspension operates. Rubber and ball bearings connect stiff metal parts together and are usually the weakest link. If the process of elimination had led you to suspect the suspension, visit a mechanic and explain the problem, especially the conditions in which the car begins to vibrate.

For the more basic inspection, raise your vehicle on a car jack, and try to pivot the tire around to check ball joints, wheel bearings, and tie rods. Here’s a quick video that explains the process:

Worn shocks & struts

Shocks and struts don’t necessarily cause vibrations, but they’re worth checking out just to be safe. The worn suspension will not be able to absorb bumps and corners well and can lead to loss of control over the vehicle. Checking the shocks is as easy as pressing down on the car above the wheel, and observing how it bounces back. More than one bounce signifies a problem with the coils or the piston.

5. Engine & Transmission

Problems with the powertrain of the vehicle can cause vibrations at 30, 40 mph & 60 mph, but the difficult part is to identify them at home. Some are easier to check than others, so I’ll take you in order of severity to rule out suspects one by one.

Clogged filters

Engine operation requires a constant and exact amount of fuel and air to run optimally. When the amount of either becomes insufficient, the pistons will not work in balance and the engine will rattle, causing vibrations through the vehicle.

Air filters come in different sizes and shapes: panel-type filters that look like brick, donut-shaped round filters, or cylindrical filters. A quick google search will tell you where to find yours, and it’s usually somewhere accessible inside the engine bay. Take off the clips and remove the filter for a visual inspection. You can gently tap it to remove some of the dirt, but considering how cheap air filters are, replacing them is always a better option.

Finding the fuel filter can be a hassle, but again, google will help you locate it. The fuel filter is a metal cylinder that you’ll have to disconnect to check its condition. Some vehicles, especially those powered by diesel have a fuel filter service indicator. It’s a small see-through cylinder that houses a tiny filter and retains some fuel that flows through the system. If it’s dirty, the fuel filter and indicator need to be changed.

As the charismatic guy from the following video explains – fuel filters can be hidden inside the fuel tank and are very difficult to access. After hearing enough horror stories about maintenance relating to the gas tank, I do not go anywhere near it despite knowing what to do. It’s simply not worth the risk, so trust me when say – take your car to a mechanic.

Failed spark plugs

Spark plugs create a crucial spark that is necessary for the fuel to ignite inside petrol engines. When more than one spark fails, the engine will have a very hard time operating. However, when it’s just one, it’s enough to let the engine run, but with one cylinder misfiring and throwing the engine out of balance.

To change the spark plugs, wait for the engine to cool off completely before starting. You will need a ratchet wrench with an extender and a spark plug socket. Gently unhook the ignition cables on the top of the engine and unscrew the spark plugs. Spark plugs are best replaced in a set, and those made by Bosch are always a good choice, but it’s also fine to stick with the brand that was already in the engine.

Worn engine mounts

If the engine was directly mounted on the body, the vibrations would not only be intolerable, but it would also lead to rapid part deterioration. Because of that, engines use special mounts which absorb the shakes and vibrations. When they fail, the engine will rattle more than usual, and the force will be enough to transfer from the rest of the mounts to the passenger cabin.

To check for engine mount problems, drive at low speeds on an empty road. Give the engine sharp bursts of gas to make the car jump forward. As it returns to its original state, you’ll hear clunking and odd noises coming from the engine bay. The second method is basically the same, except you’ll be pressing on the brake pedal to push the point of mass forward rather than back.

Transmission, driveshaft & differential problems

Any moving part will naturally cause some vibrations, and these are no exception. Through wear, the vibrations will increase beyond negligible levels and can be felt when driving, especially at speeds over 40 mph. The driveshaft is essentially a long pipe that rotates rapidly. Even a slight bend will cause it to create massive vibrations that can even make the vehicle unsafe to drive.

6. Interior

Over time, door panels, dashboard, and windows distort slightly and cause an annoying vibrating noise at speeds over 30 mph. These issues are trivial in nature, but extremely difficult to remedy. Under the intense sun, the dashboard might slightly warp, and there’s no effective way of restoring its original shape. The best thing to do is ignore the noise, and let the friction between parts wear off the contact and silence vibrations.

FAQs

Can a bad tie rod cause shaking?

Yes, tie rods cause shaking and vibrations, especially in the steering wheel. Tie rod wear is also accompanied by clunking and rattling noise coming from the front wheels, especially when turning at an intersection.

What are the symptoms of a bad control arm?

The primary symptoms are noise, tire wear, steering wandering, and vibrations inside the cabin.

What does a bad ball joint sound like?

If you hear intermittent cracking noise coming from a wheel and if the car vibrates at 40 mph, the ball bearings are likely worn to a point where they need to be replaced. Just like tie rods, turning a corner also causes loud clunking, rattling, and cracking noise. If you continue to drive on a bad ball joint, when it cracks through it can cause the entire wheel to fall off the vehicle.

How do you know if your driveshaft is unbalanced?

There are a few ways to tell if the driveshaft needs to be rebalanced. The first is vibrations coming from underneath the vehicle, followed by difficulties when turning and shuddering when accelerating. The noise ranges from clunking, squeaking to knocking and clicking. The average cost of rebalancing the driveshaft is just under $200, excluding U-joint change.

Summary

Almost every moving component of a car can cause vibrations at 30, 40 mph & 60 mph, making it difficult to find the exact cause. First, figure out where the vibrations are coming from, what type of noise accompanies them, and then through a process of elimination reduce the list to only a few suspects.

Consult the list and determine whether it’s a task you can handle yourself, or let a mechanic fix for you. I hope this guide helps you find the cause for vibrations in your vehicle so that you can fix it and get back to driving without safety risks!