S&S Advice

[Andrew R Stewart]

My many year project is coming to the metal cutting step and I need some advice. This frame will be my first S&S coupled one. I have done much home work on tubing choices WRT butting profiles and lengths and have what I feel will work on hand. A traditional sport touring design with classic tube diameters and wall thicknesses (I'm a small guy).
I've looked on line at a number of S&S frames and seen a range of coupler arrangements. So here are my main questions at this step.
- Is there a preferred direction for the coupler to be placed in the tube? The collar could on the longer portion of the TT or DT or it could spin off towards the ST. My TT will be about 55.5cm so I don't think packing clearances will dictate this choice. Is one way easier to reassemble then the other?
- There are SS disks for sealing off the passage through the coupler into the tube provided in the kit. Is there any benefits to using these other then the prevention of water through the coupler? I will do my usual large vent holes at the HT and ST so flushing out flux and crap won't be an issue.
- The coupler's lug points can be rotated to be in line with the ST or BB lug points or 90* out of phase. With my tube lengths there will be about 1-2cm of gap between the ST lug points and the coupler's. Is there a opinion to which is best?
- I have made a simple jig to align the tubes and couplers during the brazing. An Alu. channel with a cut away portion around the coupler area. Depending on the use of the sealing disks I might use a ring of Silver filler and sweat it out and add more filler from the outside as needed or only add filler from the outside. Any hints here?
This frame is both a long time wish of mine as well as a distraction from my rapidly changing life (upcoming marriage). It will have some SS bits, beyond the couplers and serve as my Sunday bike with a triple crank. Any hints, experience driven suggestions or help will be noted and heeded. I have worked on a few coupled bikes over the years but most have been tandems, and they're a different animal all together. Thanks, Andy.

[e-RICHIE]

I have found that the best way to install the S+S couplers is to do the task after the frame is built. Assemble, braze, and complete the frame. Take the top tube (or down tube) and saw out the requisite 1 3/8"length. Pull back on either end slightly, and slip on the coupler and braze. When finished, do the same for the next pipe while the first coupler is holding all in place atmo. The builds come out straighter and the installations are easier.

[Curt Goodrich]

I also like to build the front triangle first and then install the couplers. I like to do them both at the same time. After soaking off the triangle, just stick it back in the jig since it's already set up for it. Cut out the proper amount of top and down tubes. Braze in the couplers at much as possible in the jig. Finish outside of the jig. I don't use the discs. Seems like a bad idea to me to use them because it just makes getting the inevitable water out of the tubes. I typically put them in 90 degrees out of phase with the lug points.

[Jamie Medeiros]

I have always brazed the couplings into the tubes first. I tend to use down and top tubes with short central butts and a short section of straight gage tubing at the end. It is probably overkill but i just don't feel right brazing an S&S coupling to the thin part of a tube. I do it first instead of cutting apart a frame because i feel i can more accurately control the geometry of the finished frame.

[Andrew R Stewart]

Thanks all. I now have a more confident idea how I'll go about it. Andy.

[Andrew R Stewart]

So as some will see (thread "Stewart #830") I brazed S&S couplers into a couple of tubes today. And I will say that it was intersting. I preped like things were the usual steel sleeved junctions. Cleaned and fluxed. Brazed with each side of the coupler vertical, rotated to do the other side, the tube above. I felt that things went well enough during the torch work. A little bit too much heat in the collar but no burning on the tubing. The fill rate looked good, the flow went well, only a little globing of Silver. Soaked the assembly in hot hater for 15 minutes, or so. On both the DT and TT the outsides looked nice. But the collars didn't unthread. More soaking for a while longer then went to higher levels of effort. More clamping pressures on the tubes (I have pretty nice tube blocks) and the pipe wrench. By now the building collars were getting pretty gouged up. But they did finally let go. I cleaned the tubes, now seperated, once more.

My take aways are a few. Flux needs to be carefully applied given the threaded and knuckled joint that S&S couplers are. The meltin and running of the flux into the mechanical interface was some of my problem loosening them. I suspect that I may have overtightened the collars before brazing. I didn't use any pliars but did make sure the collars were very "hand tight". Third, I should have soaked the finished joints for much longer then did. Last, I should have thought about the inclusion of sacrafical collars that came with the couplers. That should have suggested that they would be a REAL good idea... only why.

Over all I think I did ok. The lack of burning of the flux on the thin walled tubes and the soaking off of the flux from the couplers suggest to me that the heat wasn't too high, just on the upper range maybe. Shinning a flashlight inside the coupler shows some flow through of filler around much of each half. I will have to do some filing clean up but that's not too different from lugs joining.

One question I do have is the cleaning up of the knuckles of the couplers. There's a browning of the surfaces. I could use mechanical methods like wire wheeling or Scotch Brite. I could use chemicals, but wouldn't know which... I am comfy with the cosmetic aspects of the out sides of the couplers but the nooks and crannies call for more then butter. Andy.