Left Handed Nut solution?

flyinace

New Member
Jul 19, 2008
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Hello everyone, I've really enjoyed reading everyone's contributions to making these motorized bikes...I recently made one and will be posting some pictures soon. Mine has been made entirely of angle iron... Anyway now i have a question.

My question is: how have you been attaching the drive spindles to the drive shaft of the engine??? Obviously welding would work but i dont have welding skills...

My 30CC Ryobi engine has a "left handed" threaded drive shaft tip. I took the clutch off and found that it had "3/8-20" stamped into it. I went to the hardware store and found a left handed nut which was also 3/8-20, however when i got home it would not fit, apparently the pitch must be different... I ended up grinding the clutch down to make a nut but i would like to be able to attach other drive spindles to the engine and this would require more nuts, or another way to attach them... What are your ideas? And has anyone been able to find left handed nuts which fit on outdoor power equipment???
 
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deacon

minor bike philosopher
Jan 15, 2008
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Call a small engine repair and parts dealer. The nut most likely is an 11mm left hand twist. I have a chainsaw with a nut like that. I had the whole clutch nut welded to a drive wheel by my neighbor. Now he is welding the left hand nut onto a galvanized end cap from the plumbing dept of home depot. I can screw pipe nipples into it.

call the lawn mower repair shop they should know what nut you need. I'm surprised you could find a left handed nut in a hardware store but then we dont have real hardware stores here any more.

How long is your drive shaft by the way
 
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flyinace

New Member
Jul 19, 2008
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Thanks for the quick reply Deacon... I was surprised that the hardware store had left handed nuts too, and they even had the size i was looking for...Only to find out it didn't fit anyway :-( I'm guessing the shaft is 3-4 inches but I'm not exactly sure...Here is a quick picture i took with my phone after i was done...Better quality pictures will come soon.
 

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deacon

minor bike philosopher
Jan 15, 2008
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I got to tell you that I love that frame you built reminds me of an erector set I had as a kid. I'm serious I do love that look.

The last 31cc motor I got from a poulan had a short shaft like that and it was a 5/16 fine thread nut. 24 I think. Five 5/16 is very close to 3/8 and it was a right hand twist.

Did you take your clutch nut to the hardware store to check it out. That's what I always do.

My chainsaw that I striped for a bike has the shaft about that long as well. My poulan I think is shorter... I also have a 25cc I have yet to finish that has a shaft about six or seven inches. Looks like nothing much is standard on these engines.
 
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flyinace

New Member
Jul 19, 2008
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Thanks for the compliment Deacon. It does look like an erector set doesn't it?!?
I have not brought the clutch to the hardware store to check it. It's funny because i don't even have a real nut, it is just the actual clutch which i grinded down to a point in which it could fit inside the bike peg. The clutch had a threaded hole in it which attached to the drive shaft of the weed eater. The thing that really has been frustrating is that the clutch has the numbers "3/8-24" stamped right into it which is why I bought that sized nut at the hardware store. The nut almost fits on the drive shaft but it stops after about a 1/8 turn and i am pretty sure that if i continue it will strip the threads on the drive shaft... Maybe i'll go and get a 5/16-24 nut and give it a whirl, it wouldn't surprise me if that stamp on the clutch was wrong...
 

deacon

minor bike philosopher
Jan 15, 2008
8,117
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north carolina
okay you either have the 11mm left thread or you have the 3/8 24 right hand thread.. All the ryobi I had used the 3/8 24 or fine thread. You probably just go the wrong thread. Did it turn on the small amount clockwise or counter clockwise
 

flyinace

New Member
Jul 19, 2008
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This months "Idiot Award" goes to...Drum roll please.... Me!!!!!!! Deacon, I read your above post while i was at work, and i sat there for a moment visualizing how i removed the clutch from the drive shaft, and I realized it was a standard 3/8-24 nut! I am such a moron! I spent two weeks looking for that left hand nut and even bought a whole box of them off the internet, and i was getting so frustrated that the left handed nuts i did find would not fit on the drive shaft! I don't know where i got the idea that it was left handed, i think i read it somewhere and just assumed it was not standard...
Anyway, i ran to the hardware store to pick up the 3/8-24 STANDARD nut and sure enough, it screwed right on the drive shaft. I could not believe the solution was so simple! So if anyone needs a 3/8-24 left handed nut, let me know, i've got about 20 of them!
 

deacon

minor bike philosopher
Jan 15, 2008
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north carolina
and that lost widget is always the last place you look because when you find it you stop looking.

Well at least you are on the way to a motorized bike you can really say you built. Not some kit you managed to get together. Sorry that was elitist I know.

Seriously always take your nuts or other motor parts to the hardware store to match up... It is the easiest thing for me to do I have found. Also I'm glad to know the new ryobi still has the same threads.

If you look around you find axle pegs with that thread pattern that will just screw on. If you leave the motor running counter clockwise it will stay tight. Not like the motor I have that I made run clockwise and today it decided to work the drive wheel loose. When they wobble everything not tied down including your liver comes loose as well.

I spent the afternoon remaking my bike. I'm not finished yet either. I got everything hooked up but I have that dreaded motor sag. I am going to have to do something about that tomorrow.