How to run bearings in this set up?

RocketJ

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Jun 20, 2018
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I'm trying to mount this gearbox through the pedal shaft, but I need bearings to keep the gearbox aligned. The problem is that the shaft on my frame is smooth bored instead of grooved like on a regular bicycle frame. The only solution I can think of is using a flanged bearing. Is there an easier way?
 

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5-7HEAVEN

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Aug 2, 2008
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Please explain more.
What engine are you using?
Is the gearbox part of the engine?
What does "shaft on my frame is smooth."?
 
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RocketJ

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Please explain more.
What engine are you using?
Is the gearbox part of the engine?
What does "shaft on my frame is smooth."?
The engine is a 212 predstor. The gearbox is not part of the engine as shown above. The pedal shaft is completely smooth as opposed to a lip that usually is found in regular bike frames to accomidate the pedal crank and bearings.
 
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PeteMcP

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Jun 27, 2017
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Am I right in thinking you're saying your frame's bottom bracket is smooth bored rather than threaded?
Either way, a suitably sized flanged bearing would be the answer.
Just curious to know more about how your engine/gearbox will be set up.
Can we see a better shot showing the entire 'box?
 

5-7HEAVEN

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Ok. The bottom bracket is normal. It needs bearings and retainers.

The gearbox needs to be solidly mounted to the bike frame.

Of course, the engine and gearbox each have to be purposely mounted to align the clutch and gearbox main shaft.

Do you know the name and model of your gearbox?

You need to tell us if your gearbox is a 1-speed gear reducer or multi-speed.

Tell us what the gear ratios are. If you can't google it, turn the shaft over TWICE. Count the # of times the output gear turns over. Then divide that # by 2.

If shaft turns over 2 times and gear revolves 1 time, gearing is
2:1.

Show us your gearbox.
 
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RocketJ

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Measure bottom bracket inside diameter and measure outside diameter of shaft. Find bearing to suit both sizes.? Is this the problem? Also frames bottom bracket is smooth without bearing cup.
Hey moto, sorry didn't get notifications. I figured it needed some flanged bearings. Apparently 2 1/8" bearings are hard to come by. I will post a better pic of the gearbox soon. I want to implement it into my build in order to run a side car in the future
 

RocketJ

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For sidecar use, have you opted for something like a Ural/Dnepr tranny with reverse gear? Just curious.
Haven't heard of those. I'll take a look.
For sidecar use, have you opted for something like a Ural/Dnepr tranny with reverse gear? Just curious.
I haven't heard of those. They look pretty nice, but I'm not sure they would fit the tight set up I have right now. Maybe for my powerplus build.
 

indian22

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Dec 31, 2014
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They make a side by side go-cart transmission with reverse that's similar in size to the one you have, actually looks the same case. Ratios are problematic for forward reverse would work out. Really a project you've gotten into!

Rick C.
 

RocketJ

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They make a side by side go-cart transmission with reverse that's similar in size to the one you have, actually looks the same case. Ratios are problematic for forward reverse would work out. Really a project you've gotten into!

Rick C.
This is probably the one you're talking about then. I've never been one to do easy projects. I'll see how this works out. Worst case scenario I'll just run a regular keyed shaft with a pulley through the pedal shaft. I just need to find bearings large enough. No one within 30 miles has even seen one that big oddly enough.
 
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MEASURE TWICE

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I'm trying to mount this gearbox through the pedal shaft, but I need bearings to keep the gearbox aligned. The problem is that the shaft on my frame is smooth bored instead of grooved like on a regular bicycle frame. The only solution I can think of is using a flangged bearing. Is there an easier way?
If there are no flange bearings large enough, I thought of my flangged pillow bearings and the holders on my jackshaft I made. Welding I did to place the pillow bearing holders. Not sure you want to weld or have some one weld holders (hangers) to have a way to place the bearings. For my off road legal on OHV bike, I actually welded plates to seal out water on both side that area and aldded spring loaded folding Honda MC foot pegs. The jackshaft was behind the engine on platform I welded also. Without welding I also suspect some adapter maybe could be made.
 

RocketJ

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If there are no flange bearings large enough, I thought of my flangged pillow bearings and the holders on my jackshaft I made. Welding I did to place the pillow bearing holders. Not sure you want to weld or have some one weld holders (hangers) to have a way to place the bearings. For my off road legal on OHV bike, I actually welded plates to seal out water on both side that area and aldded spring loaded folding Honda MC foot pegs. The jackshaft was behind the engine on platform I welded also. Without welding I also suspect some adapter maybe could be made.
I thought about that. The bearing pillows I have mount pretty well to the engine mount, but I don't feel too comfortable with messing with that piece.
 
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