Rear Wheel Arch repair

I recently noticed some small bubbles and cracks in the paint on the o/s wheel arch inside the rear door of my ’57 ZB. It is quite common to find rust coming through at this point and as this area is double-skinned it makes the repair more difficult. Nevertheless I decided to tackle it before it became any worse.

I should have started by taking a “Before” picture to show the extent of the problem but fired with enthusiasm to get on with the job I sanded away the paint to expose the rusted area and cut it away. Later I found the attached picture on the web which shows a car with a smaller amount of rusting at the same place.

Of course, the actual damage was much more extensive.The inner skin had rusted more extensively than the outer but as I didn’t fancy welding from inside the wing, I was forced to cut a much wider hole in the outer skin to give access to weld the inner one. If I had been working with a pit or a hoist this would not have been necessary. The next step was to make patterns of the two holes in cardboard and transfer the shapes to steel sheet and trim them accurately to fit.

I was surprised to find that the moulding around the edge of the wheel arch was done almost entirely in lead. You can see this quite clearly in the left hand image below. As my lead technique is limited I decided to build some of the shaping into my outer patch.

The next step was to tack, and then weld the inner patch into position and grind back using a Dremel. I treated the patch with rust inhibitor and anti-rust primer on both sides and later coated the inside of the wheel arch with underseal. I also sprayed the back of the outer patch with weld-thru zinc primer.

Welding the outer patch was complicated by the presence of so much lead. Although I cut it back to expose the edge of the underlying steel, the residual lead interfered with the welding to some extent causing sputtering (I was using a full spraying facemask to avoid inhaling the fumes).

I also tried to avoid melting the lead by coating it with a thick layer of wet newspaper which I kept spraying with water. This was surprisingly successful and very little melting took place. At this point I could have used chemical filler to finish the job but I had done a little lead work before and decided to give it another try here. I tinned the surface with solder paste using a gas torch, and then applied some lead, keeping it just hot enough to mould using a tallow-coated wooden spatula.

Quite a bit of work with files and hand abrasives was needed to get the contours as close as possible. No power tools should be used so as to avoid making fine lead dust. I was unhappy with the result using just lead, so I applied a coat of polyester filler and sanded back until I was satisfied, followed by a coat or two of primer filler to remove the remaining imperfections.

Lastly I sprayed on several top coats, and after 48 hours to let the paint harden I cut it back with Farecla to blend in with the older paint. As usual, this did not quite happen as the older paint has faded, so I have yet another shade of Twilight Grey! What seemed at the outset to be a somewhat difficult repair turned out rather well and I would encourage others to give it a try themselves.

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#1 Andy Dear 2016-03-17 19:19
The photos are a bit mixed up!
#2 Guest 2016-03-18 20:39
Thanks for the pics and article..
I have spent today cutting the rust from mine and fabricating a new arch section. My wheel arch has corroded badly and the outer section has now separated from the inside piece !
I would have liked to use lead, but sadly found the cost of it prohibitive...

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