Why do 2007 harley Davidson six speeds clatter?

Many people complain about two different noise sources on the 2006 Dyna and various 2007 models. The first is the whining 5:th gear, due to the new gearbox straight cut teeth in 5:th. Gear 2-3-4 & 6 are helical cut and thus less noise. Baker Drivetrain fixes this problem with the F6F upgrade kit.

The second is due to transmission clatter in 5:th and 6:th gear under low crusing loads. The clatter problem is due to a multitude of interacting transmission components showing up as torsion resonances maximized at lower rpm's (1500 - 2500 rpm range).

The flywheel may be just a bit too light (too little inertia) reflecting the increased torque in the new engines. However HD wants to keep engine weight down.

The new design of the gearbox may give more backlash, or a different type of backlash that interacts destructively with other resonating parts like primary transmission and final drive belt flex.

HD has quietly come up with a remedy to the clatter. The IDS is a rubber-mounted rear sproket belt-wheel retrofit, similar as used on the V-ROD and some Japanese bikes.