Advice on Jack Shaft

[Davidisabeersnob]

Need some advise on purchasing a JS for my mini bike project.

So this is the width of the spot where the JS would mount. Just over 10"


Between the top one and the bottom one on this picture, which one is best?

Is the adjustable one adjustable width or are the sprockets adjustable?

Thank you

 

[gbabins1]

What size chain do you plan to use? 35 / 41

 

[minibikin']

Call me a biased employee, but I like the ones with the adjustable plates at the bottom. Buy it with a longer shaft and trim to your desired length.:grind:

 

[Davidisabeersnob]

What size chain do you plan to use? 35 / 41

I bought the 35 chain set already.

Call me a biased employee, but I like the ones with the adjustable plates at the bottom. Buy it with a longer shaft and trim to your desired length.:grind:

So elaborate on this if you would... So on the adjustable one, do the plates move so I can narrow the JS, allowing it to be welded inside the frame rails, opposed to on top or outside?

And if I narrow the plates, would I need a longer shaft or would the shaft that comes with it work for more setup?

 

[gbabins1]

The adjustable one will allow you to adjust the chain slack from the jackshaft... by allowing forward and backward movement. But like Minibikin' said, buy the jackshaft longer than you think you will need. It can always be cut to the desired length.

 

[minibikin']

Where you weld the mounting plates dictates the width. Then the bolt on adjustable bearing hanger gives you fore and aft adjustment (chain tension). The bearings are flanged so they only need a collar on one side to keep them in place. That's why I say to order the wider kit and cut it if you aren't positive where you want the brackets.

 

[Davidisabeersnob]

Where you weld the mounting plates dictates the width. Then the bolt on adjustable bearing hanger gives you fore and aft adjustment (chain tension). The bearings are flanged so they only need a collar on one side to keep them in place. That's why I say to order the wider kit and cut it if you aren't positive where you want the brackets.

Ahhhh, got it! Sorry, I promise im not usually this thick... I looked at the picture of the adjustable JS after reading this and it all makes sense now.

Last question - 3/4 or 5/8?

 

[gbabins1]

I'd go with the 5/8.

 

[minibikin']

Yeah I prefer the 5/8. Same bearings as the wheels on most vintage minis and sprocket selection seems better


Sent from my Texas Instruments Speak and Spell...[emoji2]