Comet 30 Torque Conv sprocket location

[nascarnation]

Has anyone changed out their conv to put the chain sprocket outboard on the driven shaft instead of between the pulley and the cast bracket?

I'm repowering an old 70s kart with a HF Predator 212. It looks like that setup would let me move the engine closer to centerline of the frame, and give clearance between the drive pulley and the tire, letting me mount the engine lower.

Loosely stacking the parts, it looks like the belt pulleys can be lined up properly.

 

[supermanotorious]

you'll quickly find out you cant do that, the 5/8" jackshaft has a larger diameter and no keyway on that end

 

[mckutzy]

Can we see some pics please???

 

[anickode]

Is relocating the sprocket on the axle not an option?

 

[nascarnation]

So far so good, it's up and running.

Answering a couple questions posed:

It's a repowered (from a Lifan 79cc with a centrifugal clutch to a Predator 212cc with a "Torque-a-Verter) GK80 kart, and not much clearance to change the driven sprocket location on the rear axle without major frame rework.

On my "Torque-a-Verter" which is a Comet TAV2 Chinese knock-off, the jackshaft is keyed full length and I could just re-stack the parts. I had to do some clearance grinding on the cast ribs of the mounting plate to allow the driven pulley to rotate.

This allows moving the engine over toward the kart centerline, which seems like a good idea.

 

[anickode]

You will be dealing with what is known as "overhung load", in other words, a lateral force applied to a shaft at a given distance from the support.

When you apply throttle, the force vector is inline with the drive side of the chain, which is in a generally downward direction.

Moving the sprocket farther out on the jackshaft will not change the lateral load in terms of lbs of force applied, but it WILL give that load more leverage. It may or may not turn out OK. It could be enough to fatigue the shaft and shap it off in front of the bearing, or it could dynamite the bearings, or twist the backplate.

Twisted backplate or broken shaft are the 2 most likely IMO.

Plus, you will have to move the driven pulley farther back to give you the space on the outside for the sprocket, which will affect the alignment to the point that you may not be able to put the driver far enough back on the engine shaft to get the belt running true.

 

[nascarnation]

I had no problem aligning the drive and driven belt pulleys correctly, after I ground out clearance in the ribs on the aluminum casting....of course that makes the backplate less stiff.

Agree with your comments on the overhung loads. We'll run it til it breaks and see what happens. Of course the metallurgy on all this stuff is a crapshoot.

 

[nascarnation]

I've run a couple of these with the sprocket mounted outboard for a few weeks and so far so good. If one ever breaks, I'll be sure to follow up.