Schwinn prewar rear brake hub vs postwar tandem rear brake hub set up on balloon frame questions

[SJ_BIKER]

Picked up a green b6 bike over the weekend with dual drum brakes. My excitement quickly waned when I took it apart and realized that the rear drum brake was squeezed in there and was built to an s2 was actually a tandem drum brake unit( wider than the prewar drums). My question is does anyone have tandem brake hub that is in working order on a regular balloon frame that you tinkered with and made it work ... I have read that the frame can be stretched open so I'd like to know who has actually done that and explain methods to do it safely and also explain if the front sprocket lines up well to the rear freewheel on the drum unit for smooth pedaling action or if it's a problem how it was made to work or didn't work at all.....Any real life examples please post pics and also share your expertise or pros and cons. Just trying to see if anyone has had any luck with this setup before I abandon ship on it. Thanks for your time

 

[SJ_BIKER]

Pics of the unit I have.

 

[WillWork4Parts]

I set the Union 5sp drum Tandem wheel in a ballooner. Chainline aims great for 3rd gear, that may not help you with the single speed inch pitch though.

I used the string and a 2x4 method to spread and center the stays. You'll need some drop out alignment tools to set the drop outs back to parallel after that or you'll end up with axle nuts that creep when tightening and a bowed axle and uneven wear on the bearings. I'd spread it at home on the stand and then have your local bike shop align the drop outs, as that pair of tools is expensive.

Here's a link to the thread where I used the 2x4 and string to straighten some chainstays. Same principle, both stays being moved away from each other. Post shows the drop out alignment tools too. Post in thread 'What bike did you work on today?' https://thecabe.com/forum/threads/what-bike-did-you-work-on-today.161390/post-1639914

 

[SJ_BIKER]

Thanks for sharing. Good tips. Hope more chime in.

 

[Miq]

You can search for “cold set” and find more threads about the process. Sheldon Brown’s site has some stuff you can read. A pair of long bolts with washers and nuts threaded on them can be used to align the drop outs after you get the spacing close. Wear gloves and use your hands to move them into alignment.

 

[bobcycles]

One thing that might help.... Transplant a standard ...say...Freewheel hub from that era cluster...
they don't stick out as far... then you only have the 1/2 inch or so width growth to deal with...
Find em on New Worlds etc