Subject: Re: Welder choice for auto welding

From: [email-masked] (Eric Perozziello)
Date: Mon, 31 Jan 94 18:09:58 GMT

[email-masked] (Dave Williams)  writes:
>
> At least half of the British motorcycles ever made had their frames
>brazed together - Norton, Triumph, BSA, and Royal Enfield all did it -
>back fifty years ago the US Crosley car company built engine blocks by
>brazing together pieces - brazing is also used to hold together some
>modern tube-frame racing cars.

Why would race cars used brazed frames when there are stronger 
methods of attachment?  I didn't know they did this.  Generally, 
cost is of little consequence to these folks, right?  Brazing
wouldn't be any lighter, either-  Would it?  

-Eric

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From: [email-masked] (Harry Phinney)
Date: Mon, 31 Jan 1994 22:35:59 GMT

Eric Perozziello ([email-masked]) wrote:
: Why would race cars used brazed frames when there are stronger 
: methods of attachment?

For one thing, at-track repairs can be made more easily (it's easier to
ensure the availability of a torch than a TIG).  Also, the strength of
the joint doesn't matter as long as it's stronger than the base
material.  A well designed and brazed joint will be significantly
stronger than the material being brazed.  Also, cost is sometimes a
concern in racing vehicles, as not all racers have infinite budgets.

Harry Phinney   [email-masked]

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From: [email-masked] (f.w.kerfoot..iii)
Date: Mon, 31 Jan 1994 22:24:26 GMT

>From article <[email-masked]>, by [email-masked] (Eric Perozziello):
I can't speak for "modern" tube frame race cars, but standard practice
for road racing cars with tube frames in the 1960's and 1970's (such as
formula fords, sports racers, etc.) was thin wall mild steel tubing,
in the range of 3/4"-1 1/4" diameter by .047 - .062" wall, joined by
a process called "nickel-bronze welding". The latter is a high nickel
content brazing rod, applied with an oxyacetyline torch, with minimum
heat so a bead is created, rather than a full flow typical of
ordinary brazing. I believe that it is stronger than simple brazing.
The common alternative of the era was TIG-welded high alloy "chrome-
moly" steel, I think typically 4130. This latter construction called
for normalizing the entire frame after assembly, which wasn't feasible
in most small race shops. British suppliers, and US suppliers of cars
sold to markets typically dominated by British suppliers (i.e. the
purpose-built road-racing car market) tneded to use the nickel-bronze
welding. I believe that sprint cars and the like  were more likely to
use alloy frames. I don't know why TIG (or MIG) welded mild steel
frames were not more common.

At least in the nickel-bronze on mild steel construction, there were no
lugs of any kind. The tubing (typically round, but sometimes square
or rectangular) was carefully fitted to to minimize any gap at the
joint prior to the brazing. One of the benefits of the nickel-bronze
approach may have been that the bead provided a larger surface area,
and acted a bit like a small lug.

Frank Kerfoot
fwkhomxc.att.com