i have an older huffman tandem frame that i would like to build up. it has the "One-piece Cranks" for the BB. is there a way to insert a modern BB into a One-piece? there are no threads.

I used the TruVativ conversion kit on a couple of Varsinentals.

See here, scroll down about half way.

https://sheldonbrown.com/harris/opc.html

or...talk to the BMX guys at your LBS. They do that sort of thing all the time.

I used the FMF conversion kit on my Varsity. Next time I'll try the TruVativ.

cool, ill ask the BMX guys.... thanx.

I did this on my schwinn tandem. Esss called a bottom bracket conversion kit. You can find them on evil-bay by searching for bottom brackets in the BMX section. Narrow your search with words like conversion or eurpoean! yeah! It will sweet up the bike and you can put gears on there in the back to make it up the hills!

cool, i need all the help i cant get for the drive train. the rest i can figure out. tandems are new for me. i would like to make its like a 5 speed or something. but i also want it to be classy. haha

Watch for bottom bracket width if the spindle comes with the kit. Most BMX bikes have 74mm width while most road bikes(except Italian) have 68mm width. A BMX spindle will be too wide for your bottom bracket. There are kits available for the 68mm bb though.

damn, i knew this wasent going to be easy.... it seams like there are more tandem road cranks out there than cruiser type, does anybody know?

Ebay is always full of crank sets. As for the bb converter, you could try your friendly local bike shop for help, or Harris Cycelry(home of the inimitable velomaster Sheldon Brown) has a couple different types and will make sure you get the right one for your bike. I put one on a '66 Schwinn Super Sport(I bought it from Harris). I'm well pleased with the results(put a Stronglight 99 triple on the bike).