A torsional coupling including parts that all work together. Torque is applied to the inner member. The first stage (low torque) consists of a bonded part (rubber, inner and outer member) that is in series with a set of compression style coil springs. The torsional stiffness of the bonded part is approximately 25% of the resulting torsion stiffness provided by the coil springs. The second stage (high torque) the tangs on the inner member engage with a sprocket plate which locks out the first stage and transfers all torque through the coil springs. The coil springs are held in place by a unique geometry on the sprocket plate and the spring holders. The spring holders also prevent metal to metal contact between the coil springs and the upper and lower housing portions. Surface effect damping occurs at very high torques when the rubber molded around the tangs on the inner member rub on the bumps on the lower housing portion. A thrust bearing is used to react axial forces and to eliminate any metal to metal contact.

A drive assembly for a vehicle drive train includes a base assembly including a base hub configured for non-rotatably connecting to an outer circumferential surface of a transmission input shaft. The base assembly includes a torsional damper fixed to the base hub. The torsional damper includes an input section and an output section drivingly connected by springs. The springs allow relative rotation between the input section and the output section. The output section of the torsional damper is non-rotatably fixed to the base hub. A hub assembly extension is configured for non-rotatably connecting to an engine crankshaft. The hub assembly extension is non-rotatably fixed to the input part of the torsional damper at an engine side of the torsional damper. The torsional damper allows relative rotation between the hub assembly extension and the base hub.

A drive assembly for a vehicle drive train includes a base assembly including a base hub configured for non-rotatably connecting to an outer circumferential surface of a transmission input shaft. The base assembly includes a torsional damper fixed to the base hub. The torsional damper includes an input section and an output section drivingly connected by springs. The springs allow relative rotation between the input section and the output section. The output section of the torsional damper is non-rotatably fixed to the base hub. A hub assembly extension is configured for non-rotatably connecting to an engine crankshaft. The hub assembly extension is non-rotatably fixed to the input part of the torsional damper at an engine side of the torsional damper. The torsional damper allows relative rotation between the hub assembly extension and the base hub.

Torque is applied to an inner member of a torsional coupling. The first stage (low torque) has a bonded part in series with a set of compression style coil springs. The torsional stiffness of the bonded part is approximately 25% of the resulting torsional stiffness provided by the coil springs. In the second stage (high torque), tangs on the inner member engage with a sprocket plate, transferring torque to the coil springs. The coil springs are held in place by a unique geometry on the sprocket plate and spring holders, which prevent metal-to-metal contact between the coil springs and upper and lower housing portions of the torsional coupling. Surface effect damping occurs at very high torques when the rubber molded around the tangs on the inner member rub on bumps formed on the lower housing portion. A thrust bearing reacts axial forces and eliminates metal-to-metal contact.