Been noticing lately that the 51 Speedtwin has been leaning over more than usual. Investigated quickly this morning and see that the lug on the frame that the kick stand bolts to seems to be rotating on the frame tube. So I now have an adjustable kickstand
I need to look into this some more when I get back home but I would imagine this lug was sweated around the frame tube and that I have a moderately serious little repair to do. The frame is powder coated but hopefully the fix wont be too visible.
Im thinking maybe the least destructive way of fixing this is to drill a hole through the lug and slightly into the frame tube. Then plug weld that. I could do this on the inside of the lower frame tube so would not be visible. But with a little smoothing and touchup paint the repair would not be visible at all.
Am I talking nonsense or should I dissassemble everything, remove the powder coat and braze it together?
The tubes and lugs were "pinned" before being brazed up. My guess would be that your lug was pinned but someone forgot to run any solder into that joint (or not enough) and now the pin has sheared allowing the lug to rotate. The point being; You needn't be squeamish about pinning the lug in place but it will have to be brazed to be reliable. You may even be able to align the original pin holes and insert a new pin but I'd expect that the holes in the tubing are smeared. When you strip these frames the ends of the pins in the lugs are quite obvious. To get solder to flow in you'll have to displace the lug and persuade flux onto the tube and inside of the lug before soldering (a good trick). Might be easier in the long run to just braze on top of it. The lugs are cast steel so I believe it could also be welded in place.
Tridentman, (Love your gum by the way) When I say solder I mean Silver solder, a brazing alloy containg a high percentage of silver (40%+). It flows into very small gaps effectively and creates a very strong joint. A silver bearing alloy is what must have been used by the Triumph factory and is still holding the rest of the frame together. The traditional term for the stuff is silver solder and the process known as silver soldering but the modern term is silver brazing (so you whipper-snappers don't get confused). I guess when I'm gone there won't be anyone left calling it silver soldering anymore (snif snif).
I think you will find that the Triumph factory did not use silver solder (I am old enough to know what you mean and use the same term myself) but either brazing or what used to be known as Sif-Bronze welding (a form of high temperature braze based on bronze). Pleased that you like my gum---only problem is that I get stuck sometimes! HTH
Yeah I don't know for sure that Triumph used silver solder (silver brazing) but anytime I'm trying to get a brazing material to flow into a small gap by capillary action while minimizing the heat needed that's what I use. It's what I used to build bicycle frames years ago, worked great, basically the same procedure. I'd be surprized if they didn't use silver solder, probably from Sif Bronze, which is a trade name for a company that makes (among other things) silver solder. Trying to stabilize KNGKONG's loose side stand lug would (as I said) be well acomplished by either brazing over or welding. But it will be an obvious repair if anyone cares. Pinning it alone will probably result in the pin shearing or the the hole in the tube elongating so that the lug begins rotating again.
Thanks for the comments. Yes, I guess the best way to do this would be to sweat some braze into there as original. I would have to take the engine out and wire brush the powdercoated frame and lug down to bare metal for a good braze.
Before I go and do that though what do you think about my idea? Drill into the lug with lets say a half inch drill. Stop before going into the frame too much, then plug weld that hole? I don't know how it would compare strength wise to original but it would be like a 1/2 wide circular plug weld which could then be smoothed and made invisible. I think I could probably get this done without even removing the engine.
Just thinking if there's an easier way then breaking everything down to frame and still getting a strong result.
you are going to have a hard time welding over whatever silver solder or brass that will still be under the lug waiting to contaminate your weld. i have seen some horrible clumps of weld on many bikes on sidestand lug repairs
King, I wouldn't drill anywhere near as big as 1/2". The key is that you don't want to weaken the tube and making a big hole would do that. If you aren't to concerned about the repair being visible I would scrape the powder coat off and clean the area, position the lug and then carefully braze it in place with some common flux coated brazing rod using your oxy/acetylene torch. People braze on these frames all the time (choppers, bobbers) without noticeably weakening them. The bronze won't flow in between the lug and tube worth a darn, you'll just be lapping over the lug and tube but for a kickstand lug that should work just fine. You could also torch or arc weld it but you may weaken the tubing and cause it to crack. Best to use a low heat process here (brazing). To make the fix look like original you'd have to flow silver solder (silver braze) into the micro-gap between the lug and tube as originally done and the necessary prep would be pretty near impossible without un-building part of the frame (like I said before, a good trick). When I refer to pinning of the lug and tube the pin is about 0.080" in diameter, just enough to prevent movement during brazing. I think that plug welding would be asking for trouble in this situation.
When I say clean the area that means removing any old bronze or silver solder with files or abrasives. I too have seen really ugly repairs (well, non-repairs) on these lugs but it's possible for someone to do a neat unobtrusive job with good prep and skillful brazing.
If you want to do it without stripping the engine out of the frame then I suggest you do as Myles suggests. You can pin it as Myles suggests then braze with an oxy-acetylene torch. Try to get a good fillet of braze around as much of the circumference as you can on both sides of the lug. Should give you a good strong job. Arc welding would give you too brittle a joint in all probability as well as getting the engine hotter. MIG or TIG OK but get some insulation between the lug and the engine. Dont forget to remove the battery leads if you use arc/MIG/TIG. And no kickstarting with the bike on the stand! HTH
the 1/2 hole I was talking about drilling was only in the lug not the frame tube. Then filling that hole would essentially weld the lug to the frame. I was thinking mig so it would have less chance of getting contaminated. I question how this compares to a good brazed joint, I figure not as strong so I might be leaning towards repinning and brazing now.
Originally Posted By: Tridentman
And no kickstarting with the bike on the stand! HTH
HTH, yes, I am guilty of this.
Gonna take a better look at this over the weekend and try to figure a plan.
MIG should give you a joint with stronger tensile and shear strength but brazing will give you better fatigue strength. And it is fatigue strength that you need at this point. So my advice is certainly to braze rather than weld. HTH