Tuesday, September 7, 2010

Repair panels

When you are using a repair panel as opposed to a full replacement panel (for instance during a simple MOT bodywork repair rather than during a full restoration), take time to consider whether fitting the whole panel as supplied is wise, or whether you could usefully cut it down.
If you are able to cut down a repair panel (and still find strong metal to weld it to), then should you ever have to renew that panel —perhaps in five or ten years' time — you can then fit the full repair panel. If you alternatively use the full repair panel as supplied and subsequently have to replace it, then you will discover that when you have cut out-the old panel then theresulting hole is too large for its replacement!
Repair panels can vary greatly in quality and fit and, the more complex the panel, the more likely the user is to have to shape them. This also applies to some cheap repair panels, so buy the best you can afford.
Panels as bought have some sort of paint covering; many repair and full panels are often finished in a matt black paint (probably cellulose). I acquired four new wings for RVH 403J at the excellent Stanford Hall show in 1993 and, before fitting these, I decided to remove the existing paint and apply Tractol anti-corrosion primer in place.
I began by using 80 grit wet and dry (used wet) to remove the bulk of the paint and, after slashing my hand for the second time on the sharp edges of the wheelarch, decided to wear strong welding gauntlets! The areas around the headlamp bowls (which are one of the usual rot spots) needed another paint removal method, and I used cellulose thinners and an old toothbrush to soften then remove the paint. Because this did not, unlike rubbing down with wet and dry, also rub down the metal surface along with the paint, I was able to see exactly what state the surface of the metal was in — and I found light rusting! Surface rusting was also discovered at the wheelarch top, which is the other normal rot-spot on Beetle wings.
When rubbing down the rest of the panel I also discovered quite large areas of contamination— spots where (probably) oil lay on the steel before it was dipped and where the paint had no adhesion. Had the wings been fitted as supplied and merely painted over, then rusting would probably have broken through within three or so years.
It is a real pain to clean paint from new panelwork (it took three full days to clean and prime four wings), and A combination of rust-resistant primer, weld-through paints and seam sealant should prevent rust from re-occurring. Don't forget to give the insides of box sections plenty of protection before they are welded up.
Further protection against rust can be achieved after welding has been completed by applying Dinitrol 3125 wax (or a similar product) or old sump oil.

Popular Posts