Framebuilders - dropout repair/replacement advice needed...

here's the story:

i'm a volunteer/officer at a local bike co-op, and we are having to move from our present location. so, for obvious reasons, we're clearing out our storage.

and i found this frame (http://www.bikeforums.net/showthread.php?t=518321).

with the help of the folks in C&V, i managed to identify it.

but now i need to make it useable.

http://i23.photobucket.com/albums/b353/jhota42/brokendropout.jpg

i need to change the rear dropouts for ones that aren't broken.

either with new forward-facing drops or "track" drops.

problem is, i'm no frame builder. i can weld (GMAW/FCAW), and i do body and structural repairs on cars all the time, but have no idea where to start here. i've never done silver or brass brazing.

theoretically, i could re-melt the brazing holding the broken ends in, right? i've got access to an oxy-acetylene torch. then "just" pop new ends in and re-braze? after cleaning and prep.

or, alternatively, anybody near/in Charleston, SC who could do it for a reasonable fee?

thanks for any advice y'all can share.

here's the story:

i'm a volunteer/officer at a local bike co-op, and we are having to move from our present location. so, for obvious reasons, we're clearing out our storage.

and i found this frame (http://www.bikeforums.net/showthread.php?t=518321).

with the help of the folks in C&V, i managed to identify it.

but now i need to make it useable.

http://i23.photobucket.com/albums/b353/jhota42/brokendropout.jpg

i need to change the rear dropouts for ones that aren't broken.

either with new forward-facing drops or "track" drops.

problem is, i'm no frame builder. i can weld (GMAW/FCAW), and i do body and structural repairs on cars all the time, but have no idea where to start here. i've never done silver or brass brazing.

theoretically, i could re-melt the brazing holding the broken ends in, right? i've got access to an oxy-acetylene torch. then "just" pop new ends in and re-braze? after cleaning and prep.

or, alternatively, anybody near/in Charleston, SC who could do it for a reasonable fee?

thanks for any advice y'all can share.
That's an easy repair, but unfortunately I'm nowhere near Charleston, SC.

Although looking out the window, I'm pretty sure I wouldn't mind being in Charleston, SC right now...

If you need a dropout, I have a bag of these I use for exactly this type of repair:

http://os2.dhs.org/~john/simplex-do.jpg

so, do you think a novice brazer could replace this without trashing the frame? i learned how to weld around 15 years ago and have been doing it regularly at home and work for the last couple of years. so i understand the need for proper preparation of a joint, cleanliness, etc. and, realizing that brazing is a totally different process than arc welding.

From one rookie to another, yes you probably can. I'd practice brazing on some scrap so you know what to expect. My first brazing project after a little practicing was a repairing a cracked seatstay at the seat cluster joint. It's holding up well a year later. I had done some gas welding, so I felt comfortable wielding a torch, but if you've been arc welding a bit, then you understand a lot about heating metal.

The trickiest part is probably not the brazing itself, but the getting the alignment right.

That's an easy repair

Just curious how you would do that sort of repair. I've built a couple of lugged frames, but never done anything like that. Would you cut the old dropout at the end of the stays/slot the stays and then braze in another? Or melt the brass to remove the dropouts? Seems like the latter would really cook the stays.

I don't know how easy it will be. Getting the old one out seems difficult to me.

I would cut the old one in two and remove paint. I have always burned the paint off, but don't tell anyone. Then I would cover the joint with flux and heat the dropout. The tube will heat right up when it is time. You should see the brass start to flow a little around the edges, and then you can start gently heating up the tube. Keep most of the heat on the dropout. At some point you should be able to remove the old dropout. Anyone that has done this in the last decade can feel free to correct my proposed method :)

I would try to match the dropout. Looks Campy-ish to me. Seems like I have seen very similar ones on Ceeway. Richard Sachs sells the same make as the campy, but will only sell to pros.

Just curious how you would do that sort of repair. I've built a couple of lugged frames, but never done anything like that. Would you cut the old dropout at the end of the stays/slot the stays and then braze in another? Or melt the brass to remove the dropouts? Seems like the latter would really cook the stays.
I'd cut the dropout either with a saw or the torch. I usually use the cutting attachment on my torch; it's faster and less effort.

http://os2.dhs.org/~john/brokendropout.jpg

Then I'd pull each piece separately. Grab the piece in e.g. a vise-grip plier (wear leather gloves, too) and position the frame so that the stay is vertical above the dropout. Heat until the brass is fully melted and gently pull straight down. Don't force it -- you'll likely break off a piece of tubing if you do. If it doesn't come easily it means the brass isn't fully melted yet, so give it some more heat. When it comes out, having the stay vertical means that most of the old brass will come out with the dropout, saving you some clean up effort. Repeat with the other dropout piece, repositioning the stay so it is vertical again. Use plenty of flux and take your time. The stay ends are pretty thick and can tolerate more heat than people give them credit for.

When you go to install the new dropout, use a piece of steel plate to align the slot with the old dropout. I just used a piece of wood here to illustrate what I mean:

http://os2.dhs.org/~john/do-align.jpg

I wouldn't recommend using wood, as it has a tendency to catch fire in the presence of an oxy-acetylene flame. :)

I actually have a home made tool for this that's a bit fancier:

http://os2.dhs.org/~john/do-tool1.jpg http://os2.dhs.org/~john/do-tool2.jpg

The "hub" piece has a plate instead of an axle to keep the slots aligned with each other, and a center line marked to allow checking that the dropouts are centered behind the bottom bracket. The diamond end allows me to keep the dropout slot end at the proper distance from the BB shell and seat cluster. These are really only needed if you're replacing stay(s) as well as dropout(s).

When brazing the new dropout in, position the stay vertically beneath the dropout, so gravity can help pull the new brass down into the stay. Be generous; fill the stay end completely for about 5-10mm into the tube. It may help to use a thicker rod for this.

N.B. Some older British and European frames may have pinned dropouts. Check the inside of the down tube and seat tube in the bottom bracket to see if there are any pins. If those tubes are pinned, there's a decent chance the dropouts may be pinned as well. Remove the paint from the stays for a centimeter or so beyond the dropout and look for telltale brass rings the show the edge of a pin after it has been filed flush. If you find one, drill it out before trying to remove the dropout or you will damage the stays. Your frame doesn't look like one that would have pinned joints, but check the bottom bracket first to be sure.

Finding a lot of resistance even after thorough heating can also be a sign of a pinned dropout. If the brass is melted, you'll probably be able to see it oozing out around the edge of the pin. Let it cool back down and drill it out before proceeding. You can fill the holes up with brass and file them smooth again after you've replaced the dropout.

great info.....thanks.

I actually have a home made tool for this that's a bit fancier:

http://os2.dhs.org/~john/do-tool1.jpg http://os2.dhs.org/~john/do-tool2.jpg

.


Nice tool you have there John. Gotta make me one of them some day.:love:

Hello,

Jumping in on this thread with a similar question. I've got an 80's Katakura Silk frame with some damage, hoping for some advice.

First question, I've got a cracked dropout - I know the proper thing is to pull and replace it, but budget wise can I hand this over to my very clever welding friend and see about a repair? Crack goes all the way through, but is not visible in pic.

Hoping the pic attatched, here is a flickr link: http://www.flickr.com/photos/29677694@N05/3390781700/in/set-72157614878968198/

Second question, Assuming a fix is a bad idea, can anyone ID the dropout and/or give me a lead on finding one? I'd be interested in drops with or without der. hanger. Depending on many variables this could grow up to be a fixie. Here is the other dropout, circles are added to highlight threaded holes.

http://www.flickr.com/photos/29677694@N05/33


Third question, this wheel stay has obviously been repaired in an ugly fashion. I'm thinking get the paint off and file the lump down. Any suggestions on what I need to look for in terms of potential failure in the future? I have access to airplane mechanics who are pretty clever about looking for stress cracks, etc. Do I just turn it over to them? What are the chances of the metal being brittled from the crude weld?

http://www.flickr.com/photos/29677694@N05/3390781814/in/set-72157614878968198/

Any help and or advice would be great, thanks in advance.