Originally Posted by Arwyn Williams
Originally Posted by RichardV6
Originally Posted by Arwyn Williams
Agreed

That and silver soldering!

Having said that I've just retubed a 1933 Super Sports chassis. 150 quids worth of cold drawn seamless steel tubing held together by 175 quids worth of silver solder.....

Arwyn

Surprised brazing with maybe bronze rod is not used here Arwyn, which must be stronger surely. I'm thinking of front suspension supports fitted to ends of cross tubes. Would be interested on your thoughts.


Good point but my logic behind it is three fold.

I) Bronze filler rod requires a great deal more heat than silver solder and I was worried about too much heat affecting the lugs. Saw this issue first hand when a pair of Velocette Webb front forks failed shortly after being retubed- my metallurgist pal recons the cast lugs got too hot during the brazing process.

2) With the capillary action of silver solder in a well fitted and pinned joint, I can be certain that the silver solder has flowed through the joint. I've done test pieces using braze and its clear that the braze has not flowed through the joint.

3) With less heat required, there was practically no distortion on removing the chassis from the jig!

Also, with silver solder, I was able to preheat the tube and lug with propane then switch to oxy-propane to do the job. Brazing would probably need oxy acetylene to get the heat up.

Cheers

Arwyn

Thanks Arwyn. I recall when I had my Venom that some of the steel lugs were factory soft soldered on - think that was on front forks. Very surprised but led to believe as long as the joint surface area was large enough there would be adequate strength. At the other end of the heat scale though I recall bicycle frame lugs being brazed on - take your point about distortion though.

Richard

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