DIY Project 4
A method to repair corrosion and imperfection on aluminum
by Jean Caron, Vintage Roadster Restoration, Winnipeg, Manitoba
As we all know, Austin-Healeys have many parts fabricated from aluminium of various thickness. Items such as cockpit mouldings, door mouldings, dashboard, header rail on the tops and hardtops are all pieces that, in most cases, can be repaired using the method I will describe here. Over time, some of these parts get damaged or come into contact with other metals and start to show corrosion. I learned about this when I brought some pieces to Bob Duncan at the Chrome Pit, here in Winnipeg, and he taught me how to do these repairs by myself prior to coating.
The tools needed are few and easily obtainable. Shown here are the punches in a variety of sizes suitable for these repairs along with a light hammer. Another tool that is nice to have, but not absolutely necessary, is a metal file. You will also need sandpaper from 120 grit all the way to 1000 grit for final sanding, depending how smooth you will want your finished piece.
The repair shown below is on a 2-piece dashboard for an Austin-Healey 100 and since these dashboards are no longer available, one has no choice but repair them if you intend to retain originality. The final product is painted body colour on the early cars and black on later ones. Consequently any minor imperfections will show, thus it is imperative to repair it correctly. This next photo shows the sanded dashboard ready for repairs to an area pretty well in the middle of the dash showing a few pits caused by corrosion.
This photo shows the same general area again, this time one can see the scratched areas surrounding where repairs will be done. These scratches were done by using a metal file and it easily highlights the high spots in the metal surface.
Here is a close-up of the largest corrosion spot, just above the screw hole used to secure the dashboard to the chassis. For the purpose of this demonstration, this is the corrosion spot I will concentrate on.
The next two photos show how the punch is used on the backside of the dashboard, hammering the aluminium with light blows only. Remember that this is a metal that change shape easily and you do not want to over stretch it. Just start by hammering on the edge of the corrosion spot where it meets with the good surface, checking frequently the face side, then gradually working out towards the centre of your area being worked on. When you are satisfied that this area has been raised level or close to its immediate surrounding, then you start the process of sanding so that the raised surface blends with the surrounding area. Depending what you are working on, you may want to start with 120 grit or even 240 grit. I would not recommend using anything below 120 grit, by that I mean a grit number lower than 120 as it would tend to “bite” too much and causing deep scratches which in turn would make them much more difficult to erase.
The last photo shows the finished product, in this case done only to 400 grit. Later on, before being primed, I would sand it with 600 paper, then finish with wet sanding to 1000 grit.