Clutches in an automatic transmission control the activation of planetary gear sets. These are made up of several discs, alternating between metal and fibre inside of a metal container. When these clutches fail, the transmission cannot operate properly.
Signs of Clutch Problems
A slipping transmission is the most common sign of clutch problems. The engine will suddenly race without the vehicle moving faster, most commonly during a gear lever. The vehicle may also be slow to take off from a stop.
Check the transmission fluid to see if it is dark or smells burnt. Scan the vehicle's computer for any electronic problems. Remove and inspect the fluid pan. If the transmission pan, after being drained of fluid, has a dark, sludgy material in it, this is probably clutch material and could be a sign of clutch failure when poor transmission performance is present.
Disassembly and Inspection
Only when the transmission has been removed from the vehicle and completely disassembled can transmission clutch failure be confirmed. The fibre clutch plates have lateral grooves in them, and these grooves may be worn off. The metal clutch plates may show obvious wear or may have grooves running radially around them, sometimes quite deep. Heat stress may also be present.