driveshafts

A driveshaft, also known as a prop shaft, is a mechanical shaft that transmits torque from the engine or transmission to the wheels. In rear-wheel drive and four-wheel drive vehicles, it runs from the transmission to the differential; in front-wheel drive vehicles, shorter half-shafts with constant-velocity joints connect the transaxle to the wheels.

Construction and components: driveshafts are typically made as hollow or solid tubes, often steel or aluminum. End fittings include yokes or flanges. To accommodate suspension movement and vehicle length changes, many systems use a slip joint or splined connection at the transmission and, in longer drives, a center support bearing with a two-piece shaft.

Joint types: traditional driveshafts often use universal joints (U-joints), which transmit torque through varying angles and can introduce vibrations if unbalanced. Modern front-wheel-drive and some four-wheel-drive setups commonly employ constant-velocity (CV) joints at the ends to maintain smooth torque delivery across steering and suspension angles.

Function and operation: the driveshaft transmits engine torque to the driven wheels while accommodating changes in distance and angle between components due to suspension travel and steering. It also helps synchronize rotational speeds between connected components.

Maintenance and failure: inspect for dents, bending, rust, or loss of balance. U-joints may require lubrication or replacement when worn; CV joints are more sealed but can leak grease or fail over time. Symptoms of failure include clunking noises, vibrations, or sudden loss of propulsion, which require prompt diagnosis and repair.

Variants: two-piece shafts with a center bearing are common in longer-wheelbase vehicles; CV-joint shafts are standard on most front-wheel-drive setups; heavier-duty shafts are used in off-road or performance applications.