What is the most likely cause of a rear-wheel drive vehicle shuddering or vibrating when starting from a stop?

In a rear-wheel drive vehicle, the drive shaft transmits power from the transmission to the rear axle via universal joints (U-joints). If the U-joints are positioned at excessive working angles, this can lead to vibrations and shuddering when starting from a stop. The U-joints must operate within a specified angle to function smoothly; excessive angles can result in increased vibrations that are felt throughout the vehicle. This is often perceived most acutely during low-speed maneuvers such as starting from a stop, where the torque demands are highest and the angles are changing rapidly. Therefore, the presence of excessive U-joint working angles is a plausible explanation for the shuddering or vibrating symptoms.

Other factors such as worn tires, loose suspension components, or imbalanced wheels can certainly cause vibrations, but they might not be as specifically linked to the behavior seen when starting from a stop in the context of a rear-wheel drive vehicle. For instance, while worn tires can lead to uneven traction and vibrations, they typically manifest differently than the specific symptom of shuddering linked to U-joint angles. Similarly, loose suspension components could cause a range of handling issues but would not directly account for that specific shuddering at startup, and imbalanced wheels