What causes car to shake diving 40-50 mph?

1. Unbalanced tires: This is the most common cause of a car shaking at high speeds. When tires are unbalanced, it can cause the steering wheel to shake and the car to vibrate. This can be caused by a number of factors, including uneven tire wear, a bent rim, or a loose lug nut.

2. Wheel alignment issues: If your car's wheels are out of alignment, it can cause the car to shake at high speeds. This is because the wheels are not pointing in the correct direction, which can cause the car to pull to one side or the other.

3. Worn suspension components: Worn suspension components, such as shocks, struts, or control arms, can cause the car to shake at high speeds. This is because the suspension is not able to properly absorb bumps and vibrations, which can cause the car to feel shaky.

4. Driveshaft issues: A driveshaft that is out of balance or damaged can cause the car to shake at high speeds. This is because the driveshaft is responsible for transferring power from the engine to the wheels, and if it is not working properly, it can cause the car to vibrate.

5. Engine issues: In some cases, a car shaking at high speeds can be caused by an engine issue. This is because the engine is the source of power for the car, and if it is not working properly, it can cause the car to shake.