Construction of Old Fuel Tanks

[danf19]

Not the best category but I couldn't find a better. Perhaps this has been covered before and if so I apologize - I don't see anything when I search.
My question concerns the construction of old fuel tanks . Why were the tanks lead soldered (I think ?) and not welded ??
Would there be a better way now to make them ?
Be safe and thanks,
Dan

[T. Cotten]

Gosh Dan,... Time always marches forward.

But unfortunately, the amazing skills of the Founders of our legendary machines are lost to time, erased by industrial "efficiency" (profit).

Unless you feel you could reproduce their skills and experience (who could?), we can only guess at their motives.

But they must have been the best they had. And they did damn well, or they wouldn't be the icons we love so much.

...Cotten

[exeric]

What bike, and year are you talking about, Dan? Some early years of Excelsior were copper, and Merkels were brass which is why they are still in good shape, or easy to fix. The bottom line (literally) was cost for motorcycle factories. Steel is a lot cheaper than copper, or brass, and soldering is easy with clean, new steel, and holding fixtures. As for welding, I believe H-D was first with the new 1936 OHV tanks which were gas welded; not stick. You have to remember that manufacturers only make things as good as current, affordable technology, and ultimately, what the market will pay for. There are exceptions to that, but that always means more money

[Steve Slocombe]

It would be hard to weld the pre-1936 Harley tanks, particularly the left ones. You have a front oil compartment and a rear fuel compartment, separated by a double skinned wall with witness holes for leaks, and that wall pierced at an angle by a brass tube for the hand oil pump. After the hand oil pump was discontinued the tanks became much simpler to construct.

Early FN tanks were also copper, and don't forget the cast aluminium tanks used by Henderson and Indian around 1930.

[larry]

Were the early tanks dipped in molten solder?

[T. Cotten]

A quick search of 'terneplate', Larry,...

Says its four parts lead to one part tin.

I didn't realize it was used for roofing!

....Cotten

[exeric]

I've not seen that on any of the early bikes I've owned, Larry, but I believe some manufacturers made their tanks with 'tern plate' which is sheet steel coated with a lead/tin alloy, and some were tin plated after assembly (I think). Those are manufacturing processes that are beyond most home shop capabilities.

[exeric]

Early FN tanks were also copper, and don't forget the cast aluminium tanks used by Henderson and Indian around 1930.

I did forget that, Steve

[chuckthebeatertruck]

To build on what's already been said; I think part of the original question is actually wondering how a tank that is "soldered" together can stand the harshness of being on a motorbike. A lot of this confusion comes from our "modern" exposure to "solder." Most of what regular folks run into today is really pitiful stuff for sticking metal together. It's mostly plumbing solder. Good tensile strength, but not really for this application.

Silver bearing solders do the trick, but certainly don't flow like older solders due to OSHA stuff; and silver solders/braze really do the trick but are pricey and a different sort than used originally.

What we're missing is the wide variety of solders available 100 years ago. These ranged in composition and were lovely for all sorts of applications. My paternal grandfather introduced me to these as a boy. One of his hobbies was building model steam engines -- including boilers. Boilers were either soldered with one of the special concoctions or with silver bearing. Shells were always preheated around several gas rings/flames and trying my hand at the equivalent of furnace brazing taught me there really is an art to soldering. I'm still trying to figure it out more than 40 years later.


You can still get many types of specialty solders -- but they aren't cheap and most are silver bearing -- and unless you buy them overseas, they still don't flow right like the older stuff. I know it's a chemistry thing; but I don't know enough to know what's missing.


Anyways, that art is all but gone like the materials. The old hands knew exactly what they were doing and had very good stuff to work with. It was pretty efficient for the time and very reliable. Welding thin tanks is even more of an art -- pinholes are very easy to create. Soldering was nearly 100% reliable on clean metal and outrageously reliable on non-ferrous metals.

[exeric]

I use 50/50 solder, with Red Ruby liquid flux. I also use fire heated copper irons which I make myself, per application. For me, that combination of tools, and materials have worked the best for soldering sheet metal.