How-to Clearance 2007 and Up HD Inner Primary

In this Tech Tip video, Mike takes a few minutes to talk about the Twin Cam HD inner primary case. With 1999 to 2006 inner primary cases (1999 to 2005 Dyna), it is possible to remove and replace the charging system rotor without removal of the inner primary and the entire primary drive.

Like all Evolution models prior; the rotor on early Twin Cams can be removed after only removing the outer primary cover and removal of the compensator assembly and primary adjuster nylock nut. The HD inner primary case is not an obstruction.

For 2007 & newer Twin Cams (2006 & newer Dyna); the HD inner primary case design changed. The change coincided with the release of the 96 cubic inch engine and the new six speed transmission. This inner primary case does not allow for removal of the charging system rotor without removal of the inner primary case.

Mike explains how to clearance the HD inner primary case for a quicker, easier charging system repair. Use a die grinder and a rasp for non-ferrous metals (aluminum). Remove material from the bottom, lower surface of the inner primary cover. The material should be removed from the area of approximately 5 o’clock to approximately 8 or 9 o’clock. It is ideal to grind the HD inner primary with the case removed and on a workbench. However, it can also be accomplished with the inner case still installed on the motorcycle.

If grinding the primary case on the motorcycle, be certain to cover everything to keep chips & dust out. There will be a lot of debris. It can be helpful to use a shop vac while grinding. Hold the vacuum hose close to where you are grinding to try capturing as much debris as possible. With the inner case clearanced this way, unexpected charging system failure can be repaired quicker and with a little less work.