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Barnett Clutches Service Center & Helpdesk


Evo clutch tips
All Evos, Big Twins and Sportsters use "wet" type multi-plate clutches and diaphragm springs. Clutch pack overall thickness (OAT) is critical. In order for this type of spring to work efficiently, OAT must be precise. You can use less or more clutch plates than stock, but the OAT must remain the same. This applies to any motorcycle clutch, but it is more critical on a diaphragm spring equipped model.

All Sportsters and 1990 and later Big Twins are equipped with a "spring-plate." This is two steel plates, riveted together with a wave washer between them. These rivets have been known to come loose and fall out, causing damage to the primary. Always inspect closely when servicing the clutch. Replace if suspect.

Primary oils are very important in the wet type Evo clutches. The main purpose of oil in a wet clutch is to cool the plates. The oil also needs to have good lubrication quality, especially on the XLH models. There are many excellent primary oils available - use good quality oils and change frequently. Clean oil is cheap insurance! Always follow manufacturer spec on oil volume. Cables and cable adjustments are important. If non-stock bars/cables are used, be sure they're properly adjusted and routed for smooth action. The same applies to Hydraulic Conversions. Proper action of the master and slave cylinders will assure maximum clutch efficiency.