Centrifugal clutch questions

seabillco

Member
Joined
Jul 14, 2008
Messages
108
7-29-08
Hi, all
I've built two friction drive bikes but neither uses a centrifugal clutch.
I'd really like to build one with a centrifugal clutch so it would idle but I have two questions I'm wondering if anyone can help me with:

1) What is a good way to attach the drive spindle to the bell housing?

2) Are these little clutches from weed eater type engines strong enough to actually work?

Thanks for any thoughts!

Steve G.
Grants Pass, Oregon
 

Nuttsy

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Joined
Jun 19, 2008
Messages
328
If the system you use now for fastening the drive roller to the output shaft is a threaded configuration, just stay with that and find a clutch bell with the appropriate threads. I believe you were using BMX pegs??? Threaded hole? If that's so, you would just run a bolt through the peg and into the threaded clutch bell.
Check out some of the online scooter and go kart parts sites for the various clutch configs. And, yes they work!
WC
 

seabillco

Member
Joined
Jul 14, 2008
Messages
108
Hi, Nuttsy
Thanks for your help!
The clutch bells I have for the Ryobi engines are not threaded. They have a square hole that accepts a long, flexible, square shaft for driving something at the end of the shaft.
So, you're suggesting there are web sites that sell clutch parts that will thread onto my crank and also accept a bolt...
That is definitely what I need. If you have any web sites in mind, please let me know.
I wasn't aware such a thing existed so I'll start looking right now.

Thanks again!
Steve G
Grants Pass, Oregon
 

Happy Valley

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Jul 13, 2008
Messages
1,723
Steve, did you find what you are looking for?

I think just about all the friction drive setups I've seen use just what Nuttsy described and are plenty strong. What size engines are you planning to use?
 

seabillco

Member
Joined
Jul 14, 2008
Messages
108
Hi, HV
Thanks.
No, sadly, I'm not finding anything even close to what I want based on what Nuttsy suggested.
I'm using the Ryobi 2 and 4 cycle engines. They have a 3/8" crank that the clutch threads onto with a 24T thread.
I've been removing the clutch and replacing it with a BMX foot peg with the same 3/8 - 24 threads. That's been super easy and it works.
I'd like to leave the clutch on and SOMEHOW attach the BMX peg directly to the bell so it will spin only when the clutch is engaged due to high RPM.
I could weld the BMX peg to the bell housing but that presents several problems relating to centering the peg and the thin metal on the housing vs. the very hard and thick peg metal. The temperature required to penetrate the BMX peg would obliterate the thin, bell housing.
So, I was hoping to find a clutch with a 3/8-24 bore and a bell that is threaded, as Nuttsy says, to attach the clutch to the crank and then then the BMX peg to the bell.
I've looked at several go cart web sites and I'm not finding any clutches with a threaded bell. Also, by far, most clutches are for larger bores and have a sprocket on them for a chain drive.
If you have any ideas, I'd appreciate it.

Thanks!
Steve G.
Grants Pass, Oregon
 

seabillco

Member
Joined
Jul 14, 2008
Messages
108
Hi, again
One more idea I had to attach a spindle to the bell housing was to first attach the spindle to a plate and then attach the plate to the bell housing with small bolts. I'd have trouble keeping the bolt heads from hitting the clutch, though.
Again, the bell housing is very thin metal compared to the BMX peg.
I might be able to step it down by welding the peg to a plate that is only a bit heavier than the bell housing and then welding the plate to the housing.
I was hoping someone smarter than I am had already addressed this issue...

Thanks again!
Steve G.
Grants Pass, Oregon
 
Joined
Jul 14, 2008
Messages
71
I have a method of attaching to the clutch bell with square stock I found at both True Value and Menards. Check out my ride with a Ryobi with the stock clutch, it works so far if it stops working I will put it and go with a dirrect drive.

Hang on, I will post detailed photos later when I get home.

Hi, Nuttsy
Thanks for your help!
The clutch bells I have for the Ryobi engines are not threaded. They have a square hole that accepts a long, flexible, square shaft for driving something at the end of the shaft.
So, you're suggesting there are web sites that sell clutch parts that will thread onto my crank and also accept a bolt...
That is definitely what I need. If you have any web sites in mind, please let me know.
I wasn't aware such a thing existed so I'll start looking right now.

Thanks again!
Steve G
Grants Pass, Oregon
 

seabillco

Member
Joined
Jul 14, 2008
Messages
108
Hi, again, HV
The bell housing thread into the crank END. It is just a small 10-24 bolt to keep the housing from coming off.
The clutch itself threads onto the crank.
I think we're on the same page with welding onto the drum. It doesn't seem like a good idea to me given everything.
Hence, the problem...

Thanks again!
Steve G.
Grants Pass, Oregon
 

seabillco

Member
Joined
Jul 14, 2008
Messages
108
Hi, SVH
Thanks! I'd sure like to see that method when you have time.
I'm really scratching my head here...

Thanks again!
Steve G
Grants Pass, Oregon
 
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