Brazing springer forks

[NCriding]

Does anyone have experience with frame or fork brazing, specifically a recommendation for flux (high or low temp) and filler rod?

Through a laborious process, I removed the fork tubes from the upper and lower sections as they were dented and twisted. I now have 0.875" x 0.12" 4130 normalized alloy steel tubes to braze in and don't want to assume that using my normal white flux coated rod is the right stuff for this job. I've been brazing for years, but want to be certain I get this right.

As for set up, I'll be using my oxy/acetylene rig. I've drilled a small hole in each tube to release pressure buildup, like HD did. Finally, the entire front end will be bench assembled, i.e. rockers bolted on the legs, front axle and brake drum installed, bushings over the spring rods to line it all up and making certain everything rocks up and down nicely.

[Robert Luland]

First off, what front fork are we taking about? I've been working on that crystal ball for years. I would not use a filler rod. The rest of the socket could get contaminated during heating. I always use brushed on flux with a high quality brazing alloy to make sure I get full penetration into the joint Here's a photo of the jig we do JD fork retubing in. Bob L

[NCriding]

1936 VLD, guess I should have made that clear!

[T. Cotten]

NCriding!

Although I am not experienced with your vintage, I have had great luck dealing with freeze-fractured and other damage to later H-D forks with silver-solder.
Carl Olsen clued me to http://www.riogrande.com/category/metals/104, and low-temp silver-solders work well without damage to higher-temp fillers in original assemblies.

By any chance is your torch a "Henrob"?

...Cotten

[Chris Haynes]

I notice that the factory used red brass rod.

[NCriding]

The torch is a Marquette. Had to go into the garage and look!

[T. Cotten]

Chris!

I had to wikipedia "red brass", but my point was that anything of a lower melting point would preserve the original, as long as it is "friendly", and adheres.

NCriding!

I don't think I am familiar with the Marquette (haven't looked at my collection yet); The Henrob "Dillon" torches are un-conventional, but allow an amateur torchman to achieve pro results. Trust me I know!

Can you post pics of the damage?

.....Cotten
PS: Although I occasionally use a Peterson blue flux, I always try Stay-Silv first.
They are all basically boric acid.

[NCriding]

Thanks all, for the tips. First, I should not have used the term "filler" rod when I meant "brazing." The silver solder idea sounds good, as there are traces of the old bronze still in the sockets that could contaminate a brazing attempt. I suppose a silver solder joint will be plenty strong then?

Next step will to visit my local welding supply house (air gas) and see what they have. Here is a picture of everything roughly assembled, and the tubes I cut out. They were either tapered bottom to top, or the rust inside was sufficient to thin them out?
image.jpgimage.jpg

[T. Cotten]

NCriding!

You will wish to pull the assembly back apart for thorough cleaning and fluxing immediately before you put flame to it.
The most difficult aspect is to get the silver-solder to wick deeply into the joints. Often I beat it quite thin, so it can be forced in cold with the member.

Again, I am not familiar with your vintage (although it looks very similar to me), but the later models rusted little, even when weathered. I was told that they were "chrome-moly" and it sure still "smells" like silver-solder to me, not bronze.

If you see the solder run away from the area where you are working, stop, it has been over-heated, and must be cleaned and re-fluxed.

Let us know how it goes,

....Cotten

[NCriding]

After much diversion due to other issues, I finally got this together. The joint was much too tight to "force" it in cold, but it wicked in nicely once up to temp, similar to sweating copper pipe but requiring more heat of course. I used a "low-temp, high flow" silver solder, Radnor Safety-Silv 56 and Stay-Silv Flux. The results seem sufficiently strong, just wish I'd done a prettier job. Nothing a little hand refinishing prior to paint can't fix.
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