Understanding Car Shaking: Top 5 Causes and Solutions

The speaker addresses a common question from viewers regarding car shaking, promising to cover the top five reasons for this issue. The discussion begins with the first reason: engine misfires, particularly multi-cylinder misfires, which may not always trigger a check engine light. Symptoms include hesitation or vibration when accelerating, especially under load, indicating a potential misfire that requires immediate attention.

The second reason for car shaking is identified as vibrations felt when pressing the brake pedal. This is often due to uneven wear on brake rotors and pads, potentially caused by a sticking brake caliper piston or lack of lubrication on slide pins. The speaker emphasizes that if vibrations occur only during braking, the issue likely lies with the front brake components, necessitating inspection and possible machining or replacement of the rotors and pads.

The third cause of car shaking is vibrations experienced at highway speeds, particularly between 55 to 75 miles per hour. The speaker notes that 80 to 90 percent of the time, this is due to tire imbalance, which can occur from uneven distribution of rubber during manufacturing. This imbalance leads to vibrations at high speeds, and the solution involves balancing the tires at a tire shop, where weights are added to ensure even weight distribution.

The speaker explains that shaking inside the cabin at highway speeds is primarily due to unbalanced tires, accounting for 80-90% of cases. The remaining 10-20% can be attributed to various factors, such as severely damaged wheels or tires that have been flat for an extended period, causing bulging and uneven wear. Additionally, issues with front-wheel drive CV axles or rear-wheel drive driveshafts can also lead to vibrations. An interesting point is made about older cars with steel wheels and broken plastic hubcaps, which can also cause vibrations if not properly secured.

The discussion shifts to the absence of vibration when the transmission is in park but the presence of vibration when in drive, indicating potential issues with motor and transmission mounts. The speaker describes a typical setup with three motor mounts: a rear motor mount, a front motor mount, and a side transmission mount. These mounts are crucial for attaching the engine and transmission to the car's chassis and are designed to dampen vibrations. When the car is in drive, torque is applied to the wheels, and if the mounts are broken, this torque can cause significant shaking felt in the cabin. The speaker suggests a method to diagnose this issue by brake-torquing the engine and checking for excessive movement, which could indicate faulty mounts.

The discussion begins with the implications of using aftermarket CV axles in vehicles. It is noted that these aftermarket parts do not meet the same standards as OEM (Original Equipment Manufacturer) components. Specifically, the CV joint in aftermarket axles lacks the necessary 'give' designed to absorb engine vibrations, which can lead to harshness being transmitted through the vehicle's structure, ultimately affecting the driving experience and comfort inside the cabin.

The speaker highlights that vibrations felt in the steering wheel, particularly when driving over bumps or accelerating from a stop, often indicate problems with the vehicle's tie rods. The inner tie rod connects to the steering rack and pinion, while the outer tie rod connects to the steering knuckle. A common issue arises when the protective layer inside the ball joint of the tie rod wears out, leading to excessive play. This results in a lack of responsiveness in the steering and noticeable vibrations. To diagnose this, one should lift the front of the car and check for movement in the wheels by rocking them at the three and nine o'clock positions. Symptoms of a failing tie rod include uneven tire wear, vibrations, and the car pulling to one side.