I've been browsing and searching, but don't see enough specifics on this topic so I'll ask.

I've read quite a bit about the 30 tooth transmission sprocket conversion, and like the idea of changing the final drive ratio. Looking over my bike, there is quite a bit more forward adjustment available on the rear wheel than rearward adjustment. So I started thinking - wouldn't it be much easier to change the rear wheel drive sprocket to a 70 tooth as compared to converting to the 30 tooth transmission sprocket? It would provide a nearly identical final drive ratio. And, my rear wheel needs to come off soon anyway for a new tire.

The idea of changing the rear wheel sprocket instead of the transmission sprocket would be to keep the same 1" belt and to avoid removing the primary.

I did some searching, and I found some aftermarket chromed sprockets in 70 tooth, 1" wide, but they are expensive at more than $400.

Does anybody know of a OEM harley 70 tooth, 1" wide sprocket? If so, what is the part number? Any idea if it would be a direct bolt-on application. or if spacers would be necessary? Mine is an 08 FXDC.

Thanks.

 

https://www.latus-harley-davidson.co...-06&review=add

This is a -06 P/N, so I'd think it would work, but you'd have to double check with them for sure. Looks like it's even in silver, and a LOT cheaper than 4 bills!




Mike

 

You cannot change the belt without removing the primary! Depending on how much you want to change your gearing you may find it easier to change the compensator sprocket. I have a SE 21T kit on my Dyna and recently discovered Baker sell different sprockets.

 

I wonder what the width of this sprocket is? Thinking that the 2006 bikes had 1.125" belts.

Hoping to avoid changing the belt until it is worn out.

 

The 06s did have a 1.125 belt I have one if you need one. I put 07 wheels,rear pulley and rotors on my 06 and changed to a 1" belt.

 

In order to get the same amount of gear change as the 30T front pulley you would need to change by 5 teeth on the rear, this would require changing the belt. From what I can tell a 4 tooth change on the rear would require a belt change due to difference in pulley diameter and tooth count.
Easiest and least expensive, way to get the gearing change is the 30T front pulley, since you have to open the primary anyways.

https://www.hdforums.com/forum/5271781-post51.html

 

I hear what you're saying. 70 Tooth is pretty close though. The 32/66 setup gives a ratio between the tranny and the rear wheel pully of 2.0625:1, the 30/66 gives 2.20:1 while the 32/70 only gets the ratio up to 2.19.

The 70 tooth sprocket should be less than 0.75" in diameter bigger than the 66 tooth. I'm estimating, but it seems that the axle should need to move forward less than 1" to accomodate the bigger sprocket using the same belt. I've got that much forward adjustment, but not much rearward adjustment remaining in the stock setup.

Also, my belt guard measures more than a half inch of clearance to the belt, so that shouldn't be an issue.

Except for finding the correct rear wheel sprocket, changing the rear wheel sprocket seems like it would be a much easier job than pulling the primary off the bike to change the front sprocket. Especially given that the wheel is about to come off for a new tire.

So far though, it seems that finding the right combination of 70-tooth and 1" width (much less finding the right offset and confirming the bolt pattern) in a OEM sprocket is impossible. It seems to me that there might be a market for a reasonably priced 70-tooth sprocket to replace the 66-tooth OEM sprocket.

Thanks for the input. I think it is an interesting topic.

 

drive belt for 70 tooth is 133 teeth
drive belt for 66 tooth is 131 teeth
If you have to open the primary to change the belt, why not just do the front pulley?
You mention you have 1" of play so it will fit... Have you looked at everything, caliper, tire, rotor, wheel, fender clearance?

Let us know how it works out....

 

This is a subject I have been pondering ever since I bought my 07 FLHT. From all the info I have gathered, it seems that the front sprocket is the way to go. They only
had the 66 tooth is '07 & '08. In 2009, realizing their mistake, H-D went to a 68 tooth
set-up. The '06 and earlier 70 tooth pulleys will not work. Niether will the '09 & '10 68 tooth. The only decision I have to make now is wether to go with a 30 or 31 tooth front sprocket.

 

Are there 70 tooth 1.125 pulleys from Touring or Softail models that would interchange with an 06 Dyna?