What year is your bike? I know that on my 08 softail 5th gear is a straight cut gear, not helical. I think that it was either 09 or 10 bikes that got switched from straight cut to helical. Besides if you are feeling your clutch slipping i don't think it has to do with your actual transmission. I am running a STOCK clutch basket with a VP (variable pressure) clutch with a 480 lb spring and I haven't had ANY slipping problems, other than the tire spinning!

I suggest checking out AIM clutches...they grip tighter the higher the rpms go via centrifugal force. So you get the grip of a high pressure spring, but the clutch lever isn't going to give you carpal tunnel

 

Thanks, I have been considering the option you suggest.

My bike is a 2010 ultra with 103ci. Which has the late model 5th gear since '09' In 2010 they wanted to reduce 5th gear whine hence helical cut gears. My understanding at this point is due to axial thrust under load the movement reduces spring pressure which in stock form is supposed to be weak from the git-go.

 

I had serious clutch slippage on one of my rides. I changed the fluid to non synthetic and added an S/E spring and slippage is gone. Of course it is a 5 speed and a Dyna but that fixed it. I can hammer it as hard as I want now without issue.

 

Ahh, yeah, i always get confused on which year they changed to that helical cut 5th gear. The AIM clutche was some of the best money that I have spent... you won't be disappointed and you will no longer have that slippage issue.