Rust Repair Part 3: Using patch panels
Patch panels are a good choice for repairs to large areas,
rust outs, and damaged sections. Most rust repairs will require
patch panels of one variety or another.
There are 2 methods of obtaining patch panels - buying pre-
manufactured panels or making your own. Store bought panels are
the way to go for large panels, panels with complex shapes, or
panels which will be visible (ie lower 1/4 panels, boot floors,
etc). Thanks to British Motor Heritage, Moss Motors, etc, there
is a good selection of patch panels for LBCs. A warning about
store bought panels - always check to see that the panel you
bought has the correct contour, shape, and size before you attempt
to install it. Sometimes a panel is poorly manufactured and won't
fit properly. If so, you need to figure this out before cutting up
your car.
If you can't buy the panel you need, or if your patch is small,
you will need to fabricate your own. The normal procedure is to cut
a sheet of flat steel to size and bend it as necessary to form your
shape. Contoured panels can be formed using a shot bag and a
mallet, but I have never had an occasion to make one this way. If
the piece you need is too big or too complex, you can make the panel
in several smaller pieces with simplified shapes. One trick is
to make a template out of paper or cardboard so you can get it
right before cutting metal. Manila file folders and masking tape
make great templates.
Once you have the panels in hand, you need to cut out the area
to be replaced using a sawzall, cutoff wheel, or nibblers. Be
sure to cut back to solid metal on all sides. After this is done,
joining the new panel to the old is a fairly simple matter. You
can join the panels with a butt joint, an overlap joint, or with a
v-butt. The overlap joint and the v-butt joints are made with
specialty edge forming tools available from Eastwood and other
restoration tool places, and are a good investment IMHO. You can
get good, tight fitting panels using these joining methods. Panel
clamps are also helpful to hold everything in place until it gets
tacked together.
Fit the new panel in place, trimming as necessary to get a
good, tight fit. Hold the panel in place using clamps, panel
holders, and/or sheet metal screws. Be sure to double check the
fit and alignment before welding! Tack the panel in place using a
1/4" long bead in several places on the panel. Next, place tacks
in intermediate locations if necessary such that the tacks are 4"
- 6" apart around the panel. As you weld the panel, make certain
that you alternate sides and allow sufficient cooling time between
welds to minimize warpage of the panel and surrounding metal.
Welding in one area too long will cause heat distortion, which can
be a nightmare to correct if on a visible body panel !
With the panel solidly tacked in place, remove all clamps and
fasteners, and finish welding in the panel between the tack welds.
Once the panel is welded in place, the welds can then be ground
down flat on one or both sides as you see fit.
Well, that's the sum total of my knowledge of rust repairs. I
hope this has been helpful (and perhaps even interesting ?). Good
luck with your project cars.
Cheers !
Mike "now aren't you sorry you asked me" Harlan
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