swing arm and jackshaft q's

[MMarty]

Hey all. Has anybody used a double jackshaft arrangement? I want to use a axle only swing arm setup like the picture but the motor sits so the jackshaft sprocket would be right above the axle. I need to move the jackshaft sprocket forward by using two jackshafts and running the rear sprocket chain to the front jackshaft sprocket. That way the rear axle can pivot up and down without throwing the chain. Clear as mud? I want to avoid moving the rear axle WAYYY back. One other question, can the driven clutch on a 40 series be mounted forward of the drive? If so I could use just one jackshaft in front of the engine.

 

[exenos]

Using two jack shafts will be fine, but there may be some slack in the chain that you wont be able to remove. Shoot us a picture if you have one so we have a visual.

 

[jamyers]

From what I gather, the only critical location between a Comet driver and driven unit is the centerline distance. Meaning you could put either one anywhere in a circle based on the centerline of the other unit - forward, over, under, or wherever you wanted - as long as the centerline distance is the same and the shafts are aligned.

If you're building this all yourself, I'd think it'd be pretty straightforward to use a solid shaft as both the swingarm pivot and jackshaft, mounting the driven unit on the shaft as well as the swingarm. Then you make the engine and rear axle adjustable towards/away from the pivot-point / jackshaft, which makes adjusting the Comet belt and the drive chain 2 separate things, which is simpler than most Comet / jackshaft installations where moving the driven unit changes both the belt and the chain.

You could mount the engine anywhere in an arc in front of, above, or behind the pivot-point / jackshaft, as long at the Comet driver/driven distance is correct.

 

[Doc Sprocket]

Jamyers is spot on. No matter where you put it, it's still rotating in the same direction! Here's an old pic of my ride, that clearly shows my Comet 40 Driven ahead of the engine.

 

[MMarty]

Good deal, Thanks a lot guys. I'll just put the jackshaft towards the front of the engine cradle and build my swing arm so that my wheels aren't so far back. I only need 6" of travel or so.