On Mon, 15 Aug 1994, Alan Legerlotz 508.486-5744 wrote:
>
> I'm ready to repair the rust damage on the chassis of my MGA, and would like
> some opinions from people who have done this type of work.
>
> I have some holes in the side rails of the frame, and have two options in
> fixing them. Option 1 is to cut out the areas of the frame that are damaged
> and butt weld replacement pieces in place of the areas cut out. Option 2 is
> to take a pre cut overlay, which covers the entire area, and weld it on top of
> the damaged area.
> Here are the pros and cons I see with each option:
>
> Option 1
> ---------
>
> Pros -
> .If done properly this will be most like original
> .There will not be a thin area to trap moisture
>
> Cons -
> .It may be difficult to not get distortion of the metal, as this is
> all sheet metal, about 18 gauge.
> .Time consuming.
>
Comment: I seriously doubt distortion will be a problem if you MIG weld
an inch in one place, skip to another a few inches away (or alternate
welding on the two frame rails). Just don't crank up the machine and weld
a couple of feet without stopping, and there should be no problem. It
will take longer, but not long in absolute terms. Just fit the patch up
nice and clean with about a 1/32 inch gap all round and it should be duck
soup for a decent welder.
> Option 2
> ---------
>
> Pros -
> .Extra strength because of the added metal
> .Installation of overlay is quick and easy
Comment: maybe more strength, but why does it need more strength? If you
cut back to unrusted metal, and use the original thickness of steel for
the patch, you should not need more strength. There is just as much or
more possibility of distortion with this approach as with a good
butt-welded patch. Quick and easy, maybe, but what is the big hurry? Do
it once and do it right.
> Cons -
> .Not original construction
> .possibility of moisture being trapped between surface of overlay and
> remaining original metal.
Big possibility of moisture trap. You cannot effectively rustproof this
double sheet, either. Ungood.
One vote for butt-welded patches. Don't become a dreaded PO.
Ray Gibbons Dept. of Molecular Physiology & Biophysics
Univ. of Vermont College of Medicine, Burlington, VT
gibbons@northpole.med.uvm.edu (802) 656-8910
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