Driveshaft

A driveshaft, also known as a propeller shaft, is a mechanical component that transmits torque from the engine and transmission to the differential, which then drives the wheels. In rear-wheel drive and four-wheel drive vehicles, the driveshaft connects the transmission output to the rear axle or to a transfer case. In many front-wheel drive layouts, drive to the front wheels is provided by constant-velocity joint axles, while some vehicles still use a driveshaft to reach a rear axle in all-wheel-drive configurations.

A typical driveshaft consists of a cylindrical tube or rod with universal joints at each end to accommodate angular movement, a slip yoke to allow length changes during suspension travel, and sometimes a center support bearing and flange adapters. In some designs a two-piece shaft with a carrier bearing is used to fit between the transmission and rear differential. Materials vary by application and include steel, aluminum, and, in performance applications, carbon fiber or composite tubes to reduce weight and increase stiffness.

The shaft must be balanced and properly phased because it operates at high speed and at different angles. Universal joints can introduce non-constant velocity, which can cause vibrations if misaligned; many rear-drive systems use two U-joints with correct phasing to minimize this effect. Front-wheel-drive configurations often employ CV joints to maintain constant velocity.

Maintenance involves inspecting U-joints for wear, ensuring lubrication where applicable, and checking for vibrations or unusual noises. Worn U-joints or bearings can cause clunking sounds, vibrations, or loss of torque. Replacement typically requires balancing and may involve replacing related components such as the center bearing or flanges.