I'm doing my homework for a gear ratio change and would like to get some feedback from those who have performed this identical modification. The bike is an 02 Fatboy, Stage 1 with Duals, Andrew's 21 cams, and properly mapped. I want to squeeze in a little more low end Grunt by changing the compensator and clutch sprockets.

The stock 25 tooth compensator sprocket and 36 tooth clutch sprocket provide a gear ratio of (3.16). Changing to a 24 and 37 combination will provide a (3.37) ratio. I've identified the correct Harley part numbers which are supposed to be an exact, Bolt-On fit.

40269-85A = 24 Tooth Compensator Sprocket
37846-99A = 37 Tooth Clutch Basket

It's my understanding that I can retain my stock Primary Chain and Tensioner with this conversion. Questions are:

1. Are there any required modifications to the primary chain Tensioner?

2. Are there any alignment issues requiring different shims for the Compensator.

Any advice or lessons-learned would be appreciated.

 

I cant really answer,but i would just change the the front pulley to a 31 tooth Baker

 

have you researched whether you will need to get a different length primary chain? have you figured RPMs stock verses modded at cruising speed?
I've been trying to learn the relationships myself. So far, if my math/understanding is correct, by changing trans to rear wheel 32/66 to a 30/70 and leaving stock (34/46) primary ratio using 08 Xbones 6 speed I'll change from a dogged 2.729 to a 3.11. Still have not figured out (ball parked) cruising RPMs.
I'll be following this thread to hopefully gain some more knowledge.

 

This gearing change will raise rpm by 13% at any given road speed in any given gear. This should make a huge difference in how "nimble" the bike feels.

I would love to make exactly this magnitude of change on my 2014 Breakout, but am limited in the Harley or aftermarket parts available to achieve it, particularly since I have a chrome rear pulley that is matched to my chrome Turbine wheel, which I obviously don't want to change.

Changing my primary gearing is not advisable, because Harley offers nothing to do it, and the aftermarket solution I finally found (Evolution Industries) requires losing the "compensator" feature on the engine sprocket, and a builder / tuner who I respect has advised strongly against losing the compensator.

My most practical choice appears to be changing my output transmission pulley from 32 teeth to 30 teeth, which gives me about a 6.7% numerically higher final drive ratio. I'll need to settle for that.

In addition to the physical pulley change, I'll need a shorter belt ($$$), a lot of labor to make the change on my Softail ($$$$), and then a Power Vision tuner license or other means of accessing the tables in the ECM to enable correcting the speedometer error created by the change.

In "the good old days", gearing changes were simple and cheap. Not so any more.

Jim G

 

Jim: check out Evoindustries,they make a 49 tooth clutch basket that will lower your gearing about 10% .

 

I actually got a follow-up sales call from Evolution Industries yesterday about the clutch-based solution.

It actually changes the 46 tooth clutch sprocket to 49 tooth, so the gearing change is 6.5%. There are 2 kits, but the one that makes the most financial sense is the $720 one that provides a pre-assembled BILLET clutch basket with 49T sprocket. and the longer primary chain that is needed.

This kit results in virtually the same gearing change as changing the finl drive tranny output pulley from 32T to 30T (6.7% change), and both the primary change and the final drive change require speedometer correction via dedicated device or via Power Vision Tuner or TTS Tuner.

The primary change though MAY require a lot less labor though, since you don't need to remove the Softail rear tire and swingarm.

At any rate, you can see that the gearing change, no matter how you do it, is EXPENSIVE on a newer model Harley!

Jim G

 

is it easier and cheaper to just change the the rear sprocket from a sportster to change the gearing?

 

I would like to thank everyone for hijacking my thread. I posted a specific request pertaining to a specific modification and you've completely changed the intent of the thread.

 

Go to Baker Drivetrain website and go to gear ratio calculator. It will let you make various changes to different gears or sprockets and see impact on rpm's.

 

You're right. I apologize.

Jim G