Whenever a car shakes, it can make you feel very uncomfortable. Every driver needs enough comfortability to ensure safe driving, therefore, whenever you experience any vibration from your car, you should immediately diagnose and fix the problem.
There can be different reasons why car shakes when driving over 70 mph, such as out-of-balance tires, faulty brake system, starved engine, uneven tire wear, and so on.
There are basically many reasons why this can happen, and that is what we’ll be discussing in today’s post.
Why Car Shakes When Driving Over 70mph
There are many reasons why car shakes when driving over 70mph, but, here are the most commonly noticed reasons;
1. Out-of-Balance Tires
Whenever a car is imbalanced, it can result in car vibration at higher speeds, most notably, the 70mph range and have a cupped or scalloped wear pattern.
Hitting potholes, bridge expansion joints and curbs cause imbalanced tires, which results in steering wheel vibration through the seats and floor.
2. Misaligned Wheels
Hitting a pothole, for instance, results in misaligned wheels, which in turn causes car shakes when driving over 70 mph.
However, what will resolve this problem is proper wheel alignment, which involves the angle at which wheels hit the road.
3. Faulty Brake System
The shaking gets worse as you close in on 70 mph, which comes with a burning odor when you halt your car.
Therefore, you have to re-index the rotor one/two lug positions on the hub or replace them if excessively worn.
4. Worn Parts
Other components of your car can wear out overtime and cause vibration. These includes, shocks, upper strut bearings, ball joints, and tie rod ends.
You discover these worn parts during wheel alignment and needs replacement, especially the worn wheel bearings which make high-pitched whining or grinding noises and the tie rods that make car wheels oscillate.
5. Uneven Tire Wear
This can be a result of a broken belt or slipped belt which causes your tires to vibrate or bounce. Even new cars experience this issue, as poor-quality tires are likely to wear out faster.
To ascertain which tire needs replacement, drive in the shakes speeds, so you could feel the vibration source, and replace them if needs be.
6. Runout Wheel
When you experience shakes when driving over 70 mph, it can be as a result of a runout wheel, which means any part of a wheel or tire assembly that is imperfectly round.
This may include, tires with shifted or broken belts. It’s a dynamic problem that causes wobbling at slow speeds and excessive rattling at high speeds.
To diagnose this problem, use a tire runout gauge, off-car balancer or dial indicator, and check at the center of the tire wall, on a smooth rib for best results.
7. Low Tire Pressure
This also contributes to why your car shakes when driving over 60 mph, which is why, to maintain it, you need to always take a tire pressure gauge and inflator with you on any journey.
Raising the tire pressure about 3 psi above manufacturer recommendation in cold weather help to mitigate tire pressure drop and keep it within a favorable range.
8. Engine Starvation
Every car requires sufficient air, fuel and spark plug to properly function. The absence of the aforementioned will make your car jerk and shake, especially when driving over 70 mph.
Also, ensure that the fuel and air filters aren’t clogged or dirty, hence, constant changing will guarantee that the engine is never starved of the fuel or air it requires.
9. Shabby Suspension Components
Normally, car shakes occur within the range of 50-75 mph. But, whenever the shaking begins at a certain speed and subsequently gets worse, then its likely cause is the differential and suspension mounts.
If the damage to the suspension components become so severe, you could require a new car, rather than replacing or rebuilding the entire suspension system.
10. Overworked Powertrain
This produces a clicking noise while reversing. A bad CV axle shaft can result in shakes while braking.
Also, severe wear and abuse of your clutch, flywheel, gearbox, and especially, steering rack components cause a vibration when you hit 70 mph.
The above factors are the common reasons why a car vibrates when driving past 70 mph.
Other reasons why car shakes when driving Over 70 mph might include;
- Resonance in the exhaust
- Incorrect gasoline Octane
- Engine sludge
- Poor workmanship
- Make of the vehicle
- Rough driving
- Bad CV joints
- Excessive lifts
- Failed spark plugs or spark plug wires
- Disconnected air or vacuum hose
As you can see, there are several reasons why car shakes when driving over 70 mph.
So as a driver, if you ever experience vibration on your car when driving at a certain speed, the best thing to do at that moment is to consult with your auto mechanic for proper inspection and fixing.
But if you’re good at fixing your own cars, then we’d suggest you carefully check your car for any of the possible causes mentioned here.
Remember that it’s not wise to continue driving your car whenever you notice any anomaly as this may lead to a more serious damage and possibly accident.