SPROCKET HUB, DUAL BEARING. Drastically extends bearing life and prevents premature hub bearing bore wear.

Replacing the DR650SE's sprocket hub (aka cush drive) bearing when sprocket axial play (wobble) has become excessive should be part of regular maintenance (at minimum check every time the chain is adjusted, but best to check every time the chain is lubricated). The penalty for neglecting this may be a bearing failure, along with the attendant collateral damage, such as a destroyed hub, a destroyed swing arm, and possibly even an accident. At some point the hub's bearing bore will wear out even if the bearing is replaced at appropriate intervals. When measuring hubs with worn bearing bores, the bore is found to be worn in the bearing area but not the seal area, which points to the wear occurring during use rather than from pressing bearings out and in too many times. The main cause of the issue is that the bearing is offset significantly outboard from the point where the chain and opposing damper forces would balance. This is corroborated by the fact that bearing play develops more slowly the tighter the damper rubbers fit. Ideally, radial and torsional play would be treated as independent variables, i.e. the damper rubbers would only be used to contain rotational shock loads, and not be used to attempt to contain moment loads acting on the sprocket hub. This can be facilitated by supporting the hub on two bearings rather than one, at which point whether the damper rubbers are worn becomes irrelevant to sprocket hub/sprocket hub bearing life.

For more information about the design see Evaluation of DR650SE Sprocket Hub Bearing Strategies and for information about the production process see DR650SE Dual Bearing Sprocket Hub Production Process.

Fits 1996 and up DR650SE, 1996-2000 DR650SEU, 1997-2001 XF650 Freewind, and 1997-2001 XF650U Freewind.