A clutch disc is a mechanical assembly with friction material on both sides. It connects the engine to the transmission by a splined hub when squeezed between the Pressure Plate and flywheel.
Most clutch discs use torsional springs in the splined hub to make engagement smoother.
Clutch makers use lots of different terms to describe their friction material. The following list groups them by similar aggressiveness, engagement and wear.
Organic clutches are the most used type of clutch. They offer smooth engagement and a long life under normal driving conditions. Organic clutches do not respond well to high rpm shifting and prolonged abuse. Generally, these are made of carbon and woven aramid or metal fibers.
Kevlar is a more aggressive friction material that still offers fairly smooth engagement. It will chatter at low speed and in reverse. Kevlar glazes easily in traffic and will slip until the glaze is worn off. Once a Kevlar clutch is overheated, it should be replaced.
A hybrid clutch usually has full face organic material on one side and a more aggressive segmented material on the other. These clutches offer smooth engagement and increased power handling.
Ceramic /Metallic/ Cera-metallic/ Carbon Composite
The engagement of these materials is more abrupt and may chatter, shudder, or have a stepped engagement. These clutches will wear flywheel surfaces faster, especially in traffic situations. They tend to come in “segmented” style discs.
Sintered Iron/Sintered Bronze/Sintered Metallic
Sintered clutches are the most aggressive clutch material. They have an on/off engagement. Mostly used in drag cars and other competitions, these clutches often require special flywheels. They come in “paddle” style discs and wear the clutch assembly and flywheel quickly.
The following chart gives some guidelines for clutch disc selection. Always refer to the clutch manufacturer’s specifications for power handling and use.
|Single Disc Max HP
|Twin Disc Max HP
|700 -750 HP
|Street / Light Track / Light Off-Road and Towing
|Track / Off-Road and Towing
|Street / Track / Off-Road and Towing
|Ceramic /Metallic/ Cera-metallic/ Carbon Composite
|Street / Track / Off-Road and HeavyTowing
|Sintered Iron/Sintered Bronze/Sintered Metallic
|Track / Extreme Off-Road
Note: For heavy vehicles, sticky tires, racing, or towing heavy loads, stick to the low end of the horsepower range.