I am wanting to swap to a 30t-70t setup. I am on a 16 Fatboy S. Depending on who I ask depends on what belt will work. One tells me the stock belt will work just fine. Another tells me I need one tooth bigger and another told me I needed a 139t. My question is has anyone done this change and if so did you need a different belt? My understanding is that I have a 133t belt, if so according to what I have seen and read 133t belt will work. Figured I would ask here and on the harley-davidsonforums. Someone is bound to know the answer.

Thanks in advance

 

Yes, (according to Ronnie's Part finder), you do have a 133t belt... and yes, it will work fine. I have a 133t belt on my Rocker with the 30/70 combo, and the axle sits right in the center of the adjustment area. A stock 131t and 132t belt will also work with Softails and Dyna's for a 30t/70t or 30t/68t trans sprocket/rear pulley upgrade...
Here's everything you need to know...https://www.hdforums.com/forum/softa...p-to-13-a.html

 

For future upgraders.. If you are going to increase the rear pulley and decrease the front pulley and there is a 2-1 ratio in the change i.e.: 66-70=4 up and 32-30=2 down it is a 2-1 ratio. You will not "NOT" have to change your belt...

 

What is the real world benefit to doing something like this?

 

Lower gear ratios , means more pick up or torque ,but a lower top end.

 

TY for the reply, very helpful. Should have done a bit more research on my own I agree. Was just want g a quick answer. For that I thank you. Still trying to hunt down a place I trust to do the work

 

Thanks for posting this question. I also have a 2016 Fatboy S. I've been intending to do this research but never got to it. Now I know.

 

 

Ok so wheels are all shined up, new rear pulley is good to go and Roadhouse is ordering my front pulley now. So in about two weeks. They say 5 hours labor to put it all on. I am having them do it so I can maintain my current warranty which is good for about another year.

@Dave0176 Thanks for that heads up I didn't even think about the belt guards. Guess I ride home without them. Will modify the top once I make it home. I can live without the lower I think I will be fine. (Famous last words huh?)

 

I've done this pulley set up on my 99 Fatty. I added a 6 speed trans to make up for the loss of the top end. Now I have the best of both worlds.

Hope it works for you.