A clutch brake is a circular metal disc with friction material attached to both sides. Two tangs on the clutch brake match machined slots in the transmission input shaft. The clutch brake is mounted on these slots, between the release bearing and the transmission. This mounting arrangement allows the clutch brake to move back and forth along the input shaft. The purpose of a clutch brake is to stop or slow the input shaft from rotating, allowing the gears to mesh without grinding/clashing. This eliminates damage to non-synchronized transmissions, and minimizes the effort required when shifting from neutral into first or reverse from a standstill. AMS offers three styles of clutch brakes. The following details are useful in determining which style is better suited to the vehicles specific operating conditions and repair requirements.
1-Piece Clutch Brake: The AMS 1-piece style provides a long service life due to its thicker-than-stock steel carrier plate and beefier tangs. It is a cost-effective and easy-to-install option when the transmission has already been removed. This 1-piece style has been discontinued in O.E.M. applications and can only be removed with the transmission out of the vehicle or by cutting it off of the input shaft. This clutch brake is available in multiple thicknesses.
2-Piece Hinged Clutch Brake: This unique hinged style features a locking system that is superior to competitive designs, because it ensures a stable and positive joint that will not fail under the heaviest torque loads. It is suited for service applications, can be easily installed without removing the transmission and is available in three thicknesses.
Torque Limiting Clutch Brake: This is the current O.E.M. style unit that is recommended for all severe duty applications. It features a hub, with self-contained Belleville washers that are designed to slip after approximately 12 ft. lbs. of torque. This provides smoother engagement, and protects the brake from overloading or tang breakage resulting from driver abuse. It is a 1-piece design that can only be installed with the transmission removed. It is also available in multiple thicknesses
**Note: Resurfacing a flywheel moves the installed clutch further away from the transmission. Therefore, a thicker clutch brake is required in order to maximize the full adjustment capacity of the clutch. To determine if a thicker clutch brake is needed, place a straight-edge across the engine housing flange and measure to the flywheel friction surface (*Dimension A), don’t include the straight-edge thickness.