Briggs flathead/torque converter

[Emerica1975!!]

I recently have been changing up things on my mini bike. My frame has been and still is an Azusa frame and fork with a 1970’s Briggs 5hp flathead. The first version of the bike had 5 inch wheels with a centrifugal clutch and band brake. Now I’ve gone to 10 inch wheels and an Azusa drum brake with a knockoff brand tav2 torque converter. My problem is with the drive pulley. In order to get the drive pulley lined up with the driven pulley I have to shim the drive pulley out so far that I only have about 3/8 of in inch left on the shaft for the hub of the drive pulley to seat. I’ve tried this setup twice and both times the bolt holding the drive pulley in place backs out. The threads in the crank shaft are good. But im wondering if I need more than 3/8 of an inch for the hub to seat on? My shaft is 2 3/4 inches long ,OldMiniBikes wharehouse where I’ve been getting my parts says that’s a correct length for the tav2 kit. Maybe I just have to use a centrifugal clutch and not a torque converter but I’d rather not if possible. Any help and or tips would be appreciated. Thanks

 

[Emerica1975!!]

I just looked at my pics. I guess I actually only have 1/4 inch for hub to seat on.

 

[panchothedog]

That should work. You need to get the right length bolt that will thread in all the way with out.bottoming out. Then the correct heavy washer on the outside of the driver, use some blue lock tight, and torque to 25 lb. ft. I have a couple of karts and no more exposed shaft then what you have. They hold up just fine.

 

[Flat Head Phil]

Take the shims out and re drill yer motor mount plate to line up the sprockets. That's the right way to fix this.

 

[Emerica1975!!]

I’ll try the longer bolt I definitely think the bolt I used could have been a little short. But I don’t understand redrllling the mounting plate to make the pulleys line up.

 

[sparkwizard]

Take the shims out and re drill yer motor mount plate to line up the sprockets. That's the right way to fix this.

I don't see this as a solution, either.

 

[Flat Head Phil]

Ok I mis read the problem. I thought you're sprocket didn't line up. Different post.
I've seen shaft extensions that bolt on the end of the crank to lengthen it for mounting the outer drive sheave. Or you can make one out of 3/4" shaft and cut a key way.

 

[minibikin']

I have used a piece of 3/4 keyed shaft and cut it to length to "fill" the void or consider it a shaft extension. While it isn't directly connected to the shaft, the keyway and having the bolt pass through it helps stabilize the driver....

 

[Jim Donovan]

let's have a little more information--just how long is the crankshaft to start with? Is it the standard 2.297"?

 

[sparkwizard]

In his first post he states it's 2 3/4 inch. It looks shorter in the picture.

 

[Emerica1975!!]

The full length of the shaft is 2 3/4 inch. In the picture the shims and first half of the drive pulley are shown so that is why only .25 of an inch is remaining for the drive pulley hub. However it seems to be ok now that I’ve tried a bolt that screws all the way into the shaft and a little blue lock tite. Thanks for all the advice.