Help with chain and sprocket trouble

[nozzleman671]

I have rebuilt my Max IV and everytime i take it out something else breaks. I installed new chain and the other day my left rear chain from the tranny to rear axle snapped and folded about 6 teeth on the rear sprocket over. Can anyone help me with any ideas why this happened. The day before this happened whenever i would make a tight right turn it would sound like a chain was jumping a sprocket but i couldnt narrow down where. My chain adjusters were all inline. I had just put a new style chain adjuster on that side also. Now I have to pull the motor and replace the rear drive sprocket for $150 and hopefully it wont break again. Any ideas are welcome. I also inspected the the right rear sprocket and it appears that the right side of the teeth are chipping off. I also noticed that the two bolts on the left side of the tranny are stripped. They stay in but wont tighten down they just turn. Can this cause my issue.

[LarryW]

Are you running all the same size tires? If this machine is new to you, make sure all the sprockets are the right tooth count. Other then that is just obvious, making sure all line up and your chain is not bad.

[Wobbly]

If you had recently replaced the tranny-to-rear-axle drive chain, it would seem that it's probably not worn out and thus the cause of the problem. But worn chains can wreck sprockets and cause skipping, because the link spacing and the sprocket-tooth spacing no longer match. -Betcha' already knew that!
I'm writing primarily because you mentioned replacing that expensive rear sprocket assembly. Assuming this is for a round 1-1/4" axle, I've found a less-expensive approach that will also decrease the chance of the bolt holes becoming elongated and causing problems of their own later on. This won't solve your breaking-chain problem, but since it appears you'll need to replace the sprocket assembly, it might take some of the $ting out of the $ituation.
From shoupparts.com I bought 34-tooth and 26-tooth sprockets with 2-inch holes. These are designed to be welded onto a shaft. From speedymetals.com I bought a length of steel tube with a 2-inch OD and a 1.25-inch ID. That provides a wall thickness of 3/8", compared to the 3/16" wall of the $150 assembly you can buy elsewhere. It will be much more durable and will help prevent broken axle bolts.
If you go this route, you can order the piece of tubing in the length you want, inches and fractions thereof, or you can buy a longer piece, like I did, with the idea of making multiple sprocket assemblies, especially for the rear and middle axles. -Seems like that's where the most wear occurs on my MAX IV. Weld the sprockets onto the tube, and drill axle-bolt holes to match your axle. Someone else on this site recommended installing TWO bolts per sprocket assembly. -Makes all kinds of sense, and there's plenty of room for that second bolt. Share the load!
Anyway, I calculate that my rear-sprocket assembly costs about $57, including shipping.
Best of luck to you!!