Why does the car shake severely when driving at 100 to 120 km/h?

[StKyle]

The reasons for severe shaking when the car is driven at 100 to 120 km/h are as follows: 1. Excessive carbon deposits: If there is severe carbon buildup in the engine cylinders, it can cause spark plug blockage and valve blockage, directly leading to shaking during idling. If the car's acceleration performance has significantly declined and the shaking is persistent, the engine cylinders need to be cleaned. 2. Fuel system failure causing unstable oil pressure: Unstable oil pressure can lead to inconsistent concentration of the air-fuel mixture, not only causing shaking but also resulting in unstable idling. First, consider replacing the fuel filter, then check the oil pressure that bypasses the fuel filter. If abnormal, the fuel pump may be the issue. 3. Aging engine mounts: If the engine shaking becomes increasingly severe but the power does not weaken accordingly, it is mostly due to problems with the engine mounts. 4. Misfire or cylinder failure: The issue lies with the engine ignition coil or spark plugs. If the ignition coil fails or the spark plugs cannot fire for some reason, the car will experience shaking.

[DeBradley]

Last time I was on the highway, I encountered the same issue. When the speed reached around 110 km/h, the steering wheel shook violently. After inspection, it turned out the tire dynamic balance wasn't properly done, with two of the four wheel balancing weights missing. By the way, warped rims can also cause this, especially on roads with many potholes. Additionally, if the CV joint is worn or the driveshaft is bent, the shaking will be accompanied by seat vibration. I suggest getting a dynamic balance check first—it only costs a few dozen bucks. If the shaking persists, then inspect the chassis components. Warped brake rotors can also cause vibrations. Remember, never ignore high-speed shaking—it's dangerous to keep driving like that.

[AugustDella]

This issue is quite common. First, checking the tire dynamic balance is definitely the right move, as rubber aging or wheel rim deformation can disrupt the balance. Next is the suspension system; if the triangular arm rubber bushing cracks causing the wheels to misalign, shaking at high speeds is inevitable. Loose chassis bolts are less likely but shouldn't be ruled out, especially for cars with modified suspensions. Incorrect wheel alignment can also easily cause shaking within specific speed ranges. Additionally, don't overlook driveshaft issues, particularly for rear-wheel-drive vehicles. My advice is to immediately reduce speed to a safe level and note the speed and steering wheel vibration when the shaking occurs, which helps mechanics diagnose the problem more quickly during repairs.

[SanHailey]

My car had the same issue last time, shaking so badly that my phone couldn't stay on the dashboard. First, I checked the wheel balance and found the right front wheel was off by 35 grams. After adjustment, it improved significantly. Actually, tire bulges are even more dangerous, especially sidewall bulges, as pressure changes at high speeds can cause severe shaking. Worn drive shafts are another culprit—excessive universal joint clearance can lead to body resonance. Another detail is the brake discs; if they're warped by more than 0.05 mm, you'll feel shaking even with light braking. It's advisable to routinely check tires for bulges before highway driving and slow down immediately if you notice any shaking.

[MargaretDella]

This situation is mostly caused by wheel imbalance. Uneven tire wear or mud on the rims can disrupt the dynamic balance, and it's also common to skip balancing after a tire repair. When suspension link bushings age, misaligned wheel positioning can amplify the shaking. If the entire body vibrates, there might be damage to the driveshaft, especially common in off-road vehicles. Another hidden factor is excessive wheel bearing clearance, which can produce a humming sound along with shaking. I recommend a three-step inspection: first perform a four-wheel dynamic balance, then check the chassis bushings, and finally inspect the drivetrain. Don't delay, as excessive shaking can lead to loose screws.

[NadiaRose]

I've dealt with high-speed vibration issues many times. The primary cause is wheel dynamic imbalance, especially when the front wheel counterweights fall off. Secondly, tire deformation is common, often caused by prolonged parking or overpressure driving leading to bulges. From the chassis perspective, broken lower control arm bushings can alter wheel alignment angles, causing vibrations at specific speeds. Another frequently overlooked issue is brake caliper sticking, resulting in continuous friction between pads and rotors leading to heat deformation. The most troublesome case I encountered was a bent driveshaft, which requires professional equipment for detection. Getting a wheel balance check is the most practical immediate solution, costing around 80 yuan, while also checking for even tire pressure.