I'm of two minds on the issue at hand. The over lap method is stronger
and I have used it under the chassis mounts on the Healey where there was
no problem, just to beef it up, as a known problem area. I have also over
lap patched the Spitfire at the rear end where it was cracking (they ALL
do ) Again, it needed EXTRA strength.
However, where the existing structure, in new condition, is sufficient,
then I'd go for a butt weld, or even better, a flanged weld. (ie, get
some flanging pilers in their and create a ledge to sit the patch into
and it will turn out flush.
The important thing in both cases is not to be shy about cutting away the
rot. Get a good CLEAN area of the weld too. MIG is very fussy this way
and with spit and hiss at any oxides. Next most omportant is a good tight
fit. Get some aviation stlye blind fasteners that will hold your repair.
Remember that the weeld will be stronger than the adjacent metal so if
you have thinner metal next to your weld you will soon get cracks right
next to your repair.
After your are down get right in there and wire brush the repair, get
some paint on the area and then get some Waxoyl or some such agent INTO
the chassis box area you welded.
Also, do one area at a time. Don't cut out all the rot at onnce and then
set about to welding. That will greatly increase your chances of
distorting the chassis.
In the end the more that your repairs blend into the original the better
it is for originality etc., but don't sacrifice strength for looks.
Hope this helps.
Chris Ball
triumph@io.org
(used to do this for a living, but it was killing me )
Cough, Couch, Wheeze ....
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