3/4" Clutch On A Smooth Shaft?

[spudkilla224]

Hello everyone, I was wondering what could i do 2 make my centrifugal clutch that is a 3/4" clutch fit on a 3/4" shaft without a keyway? the clutch i had before on there just used a set screw to hold it onto the shaft and it worke just fine, but since i upgraded chain size my clutch doesn't want 2 go onto the shaft? I went from #35 chain, to #40 chain for my live axle conversion.

 

[Blazkowiez]

Does your new centrifugal clutch have a built in keyway like a Comet or a Hillard? Purchase a MaxTorque centrifugal clutch, score the shaft with a punch or likewise and hold it on using the 2 set screws. It should be just fine.

 

[Kenny_McCormic]

Very very carefully hand cut a keyway.

 

[Blazkowiez]

I think thats a useless and bad idea....

 

[Kenny_McCormic]

I think thats a useless and bad idea....

continue...

 

[Doc Sprocket]

continue...

Yeah- I want to know, too...

 

[Blazkowiez]

Most people simply don't have the skill or time to do something like that. I've seen people ruin shafts several times now. This is an expensive mistake and setting the screws in the shaft through scoring or denting will hold the clutch for most anyone's applications. Milling a new keyway if you have the shaft out of the engine and a machine shop to precision enact this idea would be good, we've had that done several times when turning down shafts and needing a smaller keyway. That is not for everyone though.

I say this only because when looking for an answer the quickest and cheapest answer is typically the best one. If setting his screws holds the clutch (in almost all cases it does) or he even has that option depending on his clutch brand then that may be the correct answer for him. If he has skill, time, and feels confident he can cut into the shaft of the engine to where nothing will be ruined then that may be an answer, but for the majority that are working on karts that is not the answer.

 

[spudkilla224]

Luckily i got the clutch on yesterday and i can see the shoe's engage. But now im delayed on the project because i was drilling the motor mount plates holes and a 1/2" milwaukee drill caught and spun my hand into my throttle assembly and my knuckle has a cut down 2 the bone. so i spent 3 hours last night in the E.R..

 

[solomon]

Oh wow, be careful. I would us a flat file, drill, and a sharpie, Slip the clutch on the shaft and use the sharpie to mark the 2 set screw holes where you want them. Then Remove the clutch and use a flat file and file down the 2 areas a little bit so a drill bit wont slip everywhere. Then reinstall the clutch, and mark the set screw holes again (since you filed away the old marks) Then remove the clutch again and use the same size drill bit as the set screws and carefully drill 2 holes about half as deep as the set screw. Then install the clutch and torque the set screws into the freshly made holes. This will act like a
key way and the clutch will not slip under heavy load. Good Luck!

 

[Doc Sprocket]

I do see your point, Blaz. I just wasn't convinced that set screws (sunken or not) would take the torque. Honestly, I'm still not convinced, but sinking the screws is much better then not. I think I'd recommend blue loctite on the screws while we're at it. If they do back out, the shaft will be mangled.

That said, of one were to carefully mark out the keyway, and remove very little material at a time, checking progress frequently, I believe it will be sucessful. Please note the "carefully", "slowly" and "frequently". Because it is absolutely true that if you go rushing in like Rambo without a jocktrap with a beer in one hand and a grinder in the other, it will likely end in sorrow...

PS- Hope you're okay, Spud...