coachbuildins

[frenchclar]

Does anyone know the method(s) that the old coach builders used to attach hand-formed aluminum panels to the wood frames?

[bobadame]

I'm pretty sure they were simply nailed on.

[oldgoaly]

Even the early steel bodied cars the skins were nailed on. tt;)

[rdupree]

The nails were relatively short (as you might expect) and used either a ring shank or spiral shank to reduce the tendency of the nails to work out.

[Rick Mullin]

For those areas where the aluminum or steel was attached directly to the wood, there were two basic nailing methods. In areas that did not show (wheel arches and such) the nails were fluted or barbed with a flat head at about three times the diameter of the nail shank.

For areas that might show (door openings, etc.), the nails were driven into the aluminum so the heads were flush. The nails were barbed or ringed and had a head similar to a finish nail. The head had a slight taper and was slightly larger than the shank. A pilot hole was drilled for the barbed shank and a slightly undersized hole was drilled just into the aluminum. When the nail was set, the tapered head tightened up in the hole and a light pass with a machine file made it all flush.

For flanged edges (door skins), a strip of steel was set into the perimeter of the wood frame to which the skin was wrapped around. On more expensive models, the door fame was clad in a thinner aluminum which was also wrapped with the skin along with the steel edge support.

A common practice now is to put a barrier behind the aluminum. This is a good practice when mounting to the steel flange or directly to the wood. I use Mylar tape as a barrier.

Rick

[Ron Naida]

The nails as you call them were actually called panel pins
They came in different sizes and had a sort of chisel shape on the underside of the head.

At one time I was able to google them but cannot find them now.

Ron

[Dick]

for restoration work & repairs
use new inexpensive/cheap long thin nails
pound them in only half way and bend over in several places to hold the panels in place for test fitting.
can be pulled out easily and new ones used each time for next fit-up
when you are satisfied with fit-up then use methods described by Rick & Ron above for the final nailing with the correct nails

[Ron Naida]

Here is a way to fit and remove the panel where
originality does not matter
I use 1/2 x 4 stainless screws. Punch a slight indent with a scratch awl.
Use a center drill to drill. It provides an 1/8" deep starter hole in the wood
and countersinks at the same timehttp://metalmeet.com/forum/picture.php?albumid=288&pictureid=7057

[Rick Mullin]

Those are some great suggestions. I use the bent nail trick a lot for fit up before committing the final hole and nail. I also use #4 screw arond wheel arhes were the edge will be hidden. Screws were used on many of the later (post 1930) coachbuilt cars. I recently re-skinned an MGTC that was being prepared for vintage racing. All of the nails were replaced with #2 x 3/8 and 1/2 stainless screws (McMaster-Carr). It stiffened things up nicely and did not require a hole much larger than the original nail. In the case of the MGTC, all of the screws are hidden by interior panels.

Rick