I really dont see a difference as to heat in my old 05 Fatboy and my 08 Heritage both with stage 1. The 6 speed on the Heritage is awesome! Cruising at 80-85 is now a real pleasure and effortless. I haven't noticed any different sounds between the two trannys. I have always use Syn 3 in my 2 Harleys but I do plan on switching the tranny fluid to either shockproof heavy or mobile 1 just to see if there is a difference.

 

fine with the 07 heritage at 10k. you will notice more "noise" with windshield on but frankly neither my self or many friends with the 96 and 6 speed have had anything to whine about.the 5th gear issue is a nonsense. friends with the 88 and 5 speed can't wait to upgrade after riding the new models ( softtail and dyna ).

 

If the search was working, you would find a ton of info, and opinions, on heat and noise questions for the 96"/6 speed. Some claim problems, others claim no problems. I have read that the 1st and 5th gears are straight cut gears (hence the sound difference) and the others gears are helical cut.

 

Old thread I know but my 07 fxstc has the six speed and there is definately a different sound out of 5 th gear than any of the other gears and I'm confident that it is simply the way that gear is cut and how it meshes with the other gear that causes this noise and isnt actually a problem per se
Sean