I have a '72 stock Harley and need to know what the recommended sprocket (tooth) are for the engine, transmission and rear wheel. I assume the clutch basket is unchanged. Thanks
There are several choices on re-gearing for the sidecar.
Depending on the main use: Hiway or in town and loading all come into play.
Your stock engine sprocket for the solo bike is probably a 24 tooth. Clutch basket, 44 tooth. Trans output sprocket a 24 and the rear from 45 to 47 (guessing here).
Pan and Shovel sidecar engine sprockets are sometimes 21 or 22 tooth.
The easiest way to change final drive ratios is by changing the rear sprocket from 45, 47 (stock) to 51 tooth or more. That only requires resetting the rear wheel or maybe adding a few links to the final drive chain.
The transmission output sprocket can be dropped to a 23 or 22 also increasing the gear ratio without major adjustments being needed.
For extra low end grunt with the loaded car, a final drive ratio of around 4 to 1 is very tractable but if you want less low end pulling power and high road speeds you might want a lower numerical ratio.
Either way by making changes from the transmission back you don't have to dig into the primary case or reset the gearbox.
Swap meets are a good economical source for sprockets, next would be cycle recyclers. New gets expensive fast if you are experimenting with final drive ratios and don't know which parts you need to get where you want to be.
Lonnie
Good call! I already have a 51 tooth on the rear sprocket and my '72 Harley Manual calls for a 22 tooth on both the tranny and engine. I will most likely do a little combination of both hwy and city. I'm guessing a little more city though. Do you think I need to change the engine sprocket? It's winter and I don't mind if I have to, but do mind if it's going to be a waste of time. I have a set of spare gears that a friend gave me and they are both 22. What do you think? Thanks again for your invaluable advice. - Mike
Mike,
I'd go for the 22 tranny sprocket first and see how close you are to where you want to be. then maybe go a tooth or so one way or the other on the rear sprocket to tweak it. Then if not right, you can open up the primary and drop in the 22 tooth engine sprocket.
With 22/44in and 22/51 out on my '50 Pan rig, I was between gears driving in town at 35 MPH lugging or over revved. Revving a little much at highway speed also. Went to 22/44 in and 24/51 out which worked for me but the subsequent owner dropped two teeth on the rear sprocket for better cruising.
I guess it's a matter of preferance and how you ride.
Lonnie
What's this 'Sprocket' you speak of? 🙂
Dave
Dnepr MT-16
Dave,
On the earlier V-twin Harleys the sprockets are: The engine output sprocket that drives the clutch basket sprocket in the primary case via the primary chain and the transmission output sprocket that drives the rear wheel sprocket via the final drive chain.
The engine, transmission and rear sprockets come in different ratios, hence different amounts of drive teeth to accomplish this.
Lonnie
