820 starter cup

[Jim Waltz]

Dang, are we all smart or what?

[ted johnson]

What.

[Brad Rose]

I have a stepped crank. I better use the key.

[ted johnson]

Brad, Key, Absolutely! Ted

[Michael Drechnowicz]

lap the clutch on the crank. clean everything and if you use 30 ft lbs it won't slip. Has to be a taper crank for that process.

Forgive my ignorance but how do you lap the clutch to the crank? If you do this do you not use a key?

Thanks,
Michael

[ted johnson]

Michael, if you have the McCulloch-style tapered crank in your West Bend, you may use valve grinding compound to lap your clutch hub to your crank. Once that's done, you do not have to use a key. Apply a few small dabs of the compound to the tapered portion of the crank, shove the clutch hub on and rotate it back and forth quite a few times. Take the clutch off and wipe the crank clean. Look for a uniform gray color on the taper. If it's not uniformly gray, repeat the process until it is. Clean clutch and hub completely with solvent, and install the clutch. Apply a good drop of BLUE Loctite to the threads and torque the nut to the specified torque. I've been using 280 inch pounds (23.5 foot pounds) on the 3/8" clutch nuts. Ted

[Bill Peck]

Michael, if you have the McCulloch-style tapered crank in your West Bend, you may use valve grinding compound to lap your clutch hub to your crank. Once that's done, you do not have to use a key. Apply a few small dabs of the compound to the tapered portion of the crank, shove the clutch hub on and rotate it back and forth quite a few times. Take the clutch off and wipe the crank clean. Look for a uniform gray color on the taper. If it's not uniformly gray, repeat the process until it is. Clean clutch and hub completely with solvent, and install the clutch. Apply a good drop of BLUE Loctite to the threads and torque the nut to the specified torque. I've been using 280 inch pounds (23.5 foot pounds) on the 3/8" clutch nuts. Ted

Am I to assume that technique will work on a Mac crank? I'm putting a 91B together now that has a crank that's chipped at the keyway. I used to have the piece that broke out and I just put it back in with the key and tightened everything down, but now I can't find the piece. Would it be wise to fill the chip with JB Weld (or some other form of epoxy) before lapping the clutch on?

[ted johnson]

Bill, I doubt that filling the chip would increase strength. Give the lap, Loctite and torque method a try. It'll work on any tapered crank. The main diff between the keyed cranks and the non-keyed ones is the fact that non-keyed Mac cranks have left hand threads. This means that the nut is self tightening to a degree. On a right hand thread crank, a good lap job and the Loctite and torqueing are very important so that the nut does not tend to loosen. Ted

[steve welte]

I learned a few years ago when i had a clutch come loose 2 times in one day when using no key that a torque wrench is important. Torqued the nut to 30 ft lbs and have never had another come loose. This was on the taper crank. I had been using clutch holding tool and a 3/8" ratchet with a 5/8" socket before. You would think that would be enough. Wrong. It took the torque wrench.

[jeff brown]

I use teds process but I don't remove the residue from the hub only the crankshaft.  The minor amount of residue left in the hub of lapping compound bites into the shaft is my theory .      

If it has a key I clean both parts and use the key.