Modified Crankshaft Pulley Theory = No More Hassles!!

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Modified Crankshaft Pulley Theory = No More Hassles!!

Postby Peter Reynolds » Sun Mar 07, 2004 5:55 pm

Here is an idea I formulated while I was reassemblying the cub... There is one thing about the cub that I hate, and thats the crankshaft pulley. Here is my plan... Next time I have my pulley off, why not take it to a machine shop, and have them ream a few thousands of an inch off the I.D. of the pulley - just so it's a hand press fit on the snout of the crank. (Like a Piston Pin) Then to prevent the pulley from sliding off the front of the crank, use a big washer and half inch bolt threaded into the snout of the crank to hold it back. That way, if I ever need to change the seal in the future I can still use a puller to get it off, but it won't take much pressure to back it off. Crank pulley removal could just take seconds - with a little anti-sieze applied, you'd never have to worry about the pulley becoming one with the crank. what do ya'll think? couldn't this be done on a lathe at a machine shop? The only downside I can think of is that the hand crank couldn't be used anymore.

~The farmall cub kid - who finally got his act together~

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Postby George Willer » Sun Mar 07, 2004 7:02 pm

Peter,

That's an interesting thought, but you may not know why the pulley fits so tightly. If it isn't a tight fit, it will move slightly each time the engine fires, eventually wearing the bore and crank both, and making both useless. I'd recommend strongly that you instead research better and easier ways to get it off next time. I had a pulley here that I scrapped because it didn't fit tightly enough because someone had apparently sanded it out oversize.

Anti-sieze should NOT be used for the same reason. That torsional vibration is what shears keys in single cylinder engine flywheels when anti-sieze is used.

FYI...You may not know that it is very difficult to ream a bore accurately with a keyway?

In any case, it's good to see that you have your thinking cap on. Keep it up! That's how you will learn.

It's good to get a report on your project. When do you think we will see the finished product?
George Willer
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Postby Jack Donovan » Sun Mar 07, 2004 8:44 pm

Peter- Just to add a little to what George confirmed, If it were done as you expained then you should have a Left hand threaded bolt. I had a VW Deisal that the bolt came loose3 on and it distroied the engine. It recked the pully, keyway in crank, through the timming off and the valves hit and went through the pistons and broke the block. A bad experance" Jack"
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