How not to do a 30 series j/s

[Kartorbust]

Just watched Rather B Welding's latest video on his long traveled dual engine buggy and he ended up snapping the aluminum backplate on a 30 series. He had to move the sprocket on the jackshaft more to the right to line up with the trailing arm axle sprocket. Turns out that doing so puts a ton of stress on that backplate and it snapped off, throwing the belt, chain and driven off.

https://www.youtube.com/watch?v=mkt1FWhasNc

 

[anickode]

There was somebody on here that did that. Snapped it right in two.

 

[65ShelbyClone]

In physical terms, the engine pulls forward on the driven pulley and the drive chain pulls backward on the sprocket.

Having the sprocket and driven on opposite sides of the plate means that the plate is subjected to a large bending force as it alone has to resist the driven shaft trying to twist fore-aft.

Putting the sprocket and driven pulley on the same side of the plate moves the bending force away from its center so the plate mostly has to resist a tension force on one end of the shaft. They have plenty of material to withstand that which is why it's both the recommended layout and why they tend not to break that way.

The only way to reliably hang a sprocket further out is to use a shaft that is supported on both ends, aka a jackshaft.