Jack shaft issues

[Sidewinder Jerry]

Hmm... Okay valid point I'll give you that. I did not expect to learn something today. I'm suprised the rake of the bike is not taken more into consideration

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[tombenn444]

Ok so does when using the jackshaft..it's not the rear wheel turning the engine when. Starting it's started by directly turning the pedals? If so then the small jackshaft sprocket goes on the left side?

 

[tombenn444]

Jackshaft... More like jokeshaft. This thing driving me up the wall not in a good way. It just won't stay tight the engine always shifts to one side and that loosens the chain and then it throws the chain or breaks it EVERYTIME. Ive tried locktite, I've tried building chain tensioners (tried retraction style and expansion style.) I've tried bigger mounting plates. I've tried repositioning, I've sacrificed a goat and still the engine continues to shift. I'm not going hard on the gears. I'm about to drill straight through my frame and bolt it to the tubes. I've torqued the clamp bolts down so hard it's flattening my frame tubes just to give you an idea of how much torque I'm giving these fasteners. I realize that there is no kind of procedure in place for this modification I'm just asking for some tips from some people who have gone through the same troubles as me.

 

[Urban Fatbiker]

Jackshaft... More like jokeshaft. This thing driving me up the wall not in a good way. It just won't stay tight the engine always shifts to one side and that loosens the chain and then it throws the chain or breaks it EVERYTIME. Ive tried locktite, I've tried building chain tensioners (tried retraction style and expansion style.) I've tried bigger mounting plates. I've tried repositioning, I've sacrificed a goat and still the engine continues to shift. I'm not going hard on the gears. I'm about to drill straight through my frame and bolt it to the tubes. I've torqued the clamp bolts down so hard it's flattening my frame tubes just to give you an idea of how much torque I'm giving these fasteners. I realize that there is no kind of procedure in place for this modification I'm just asking for some tips from some people who have gone through the same troubles as me.

Yep same troubles. Using U-clamps won't hold it, and when it pulls forward on right side under torque it can twist that bracket.

You'll need to beef it up. My suggestions, weld in standoffs, use brackets on back side, and cut half-moon 'clamshell' to weld on clamping sides.

Use chain tensioners both sides. Use the third plate option like SBP sold.
Additionally, I dimpled shaft at every set screw location, added lock collars, lots of locktite. Not a single loose nut or screw in over 200 miles.

Note I used a compression collar on left side.
Makes it easier to remove entire shaft from right side if needed w/o breaking down entire shaft.

 

[Deleted member 33388]

Think a 3in tire would squeeze in there. I had wanted to do that with a Cranbrook but by the looks I don't think it will.

 

[rusty.western.flyer]

I can tell you this for a fact. That giant reverse thread tap needed for one side of that bracket adapter will cost more than the premade bracket adapter, likely by at least double. I have an extensive tap and die collection, and those reverse thread ones tend to be harder to find and more expensive by default. One as big as needed for a bottom bracket = $$$$$

This. I bought a 48mmx1.5mm tap to re-thread BMW strut housings. Not only was it expensive, you ever try to turn a tap that large?

 

[rusty.western.flyer]

 

[DAMIEN1307]

you ever try to turn a tap that large?

Ahhhhh...No problem, just slide that sucka into your Black and Decker power drill and let her rip...lol...lol.

 

[rusty.western.flyer]

Ahhhhh...No problem, just slide that sucka into your Black and Decker power drill and let her rip...lol...lol.

While you joke, I have a 1970's right angle Milwaukee 3:1 reduction drill. It will literally spin a 200lb man around like a tether-ball at 600rpm.

 

[tombenn444]

Yep same troubles. Using U-clamps won't hold it, and when it pulls forward on right side under torque it can twist that bracket.

You'll need to beef it up. My suggestions, weld in standoffs, use brackets on back side, and cut half-moon 'clamshell' to weld on clamping sides.

Use chain tensioners both sides. Use the third plate option like SBP sold.
Additionally, I dimpled shaft at every set screw location, added lock collars, lots of locktite. Not a single loose nut or screw in over 200 miles.

Note I used a compression collar on left side.
Makes it easier to remove entire shaft from right side if needed w/o breaking down entire shaft.
View attachment 177621

can u send more pictures of your setup?