590190 Thrust washer, mainshaft. left

This left-side mainshaft thrust washer is a precision-made component for late 1979 to 1990 4-speed XL Sportster transmissions. Replacing OEM 35216-79, it is used to manage end-play and reduce friction between rotating parts on the mainshaft. Proper spacing is critical in Sportster gearboxes to ensure smooth shifting and to prevent premature wear on the gears and shafts. During a transmission teardown, these washers should always be inspected for thinning or scoring. This MCS replacement provides the factory-spec thickness and durability needed to keep your Ironhead or early Evolution Sportster shifting reliably for years to come.