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MG TC Door Panel Repairs

SteveWallace - 21/6/17 at 04:48 PM

I've started to work on the doors on my 1949 MG TC. These are wood framed with a metal outer skin. Stripping the paint of one of them has revealed 3 smallish rust holes that had been previously repaired with filler. I've taken all of the old filler off, gone back to solid metal and treated any remaining rust spots.

The skin is too thin and the holes too small to bother with cutting a section out and welding a new bit in (also too much risk of distortion). Therefore, what is the best stuff to fill the holes with?

Its a classic car, so it maybe deserves something better than cheap filler. Therefore I was thinking maybe something like Isopon Metalik, but are there better options for a repair of this type?

Description

ste - 21/6/17 at 05:26 PM

it can be done with glass fibre although there's nothing too hard about welding a patch in, but again, you will need filler to get the finish

theconrodkid - 21/6/17 at 07:04 PM

lead ?.

Vmax1974 - 21/6/17 at 07:50 PM

quote:
Originally posted by theconrodkid
lead ?.

Agreed thats what they would have used when it was new therapeutic to work with too

perksy - 21/6/17 at 09:19 PM

Lead loading

Watched an old guy do it on a classic car restoration course I did at the local college

Mr Whippy - 22/6/17 at 06:05 AM

personally since the door skin is flat I think I would just change it. I've done this on quite a few cars and it's by far the best outcome. I think I'd use 1.5mm aluminium sheet for it rather than steel as it's easier to work and will last longer.

Mr Whippy - 22/6/17 at 06:07 AM

quote:
Originally posted by perksy
Lead loading

Watched an old guy do it on a classic car restoration course I did at the local college

Don't think I'd use that due to the ash frame behind

907 - 22/6/17 at 06:59 AM

I'd replace that bottom edge with new steel welded in.

Distortion is caused by the weld and the area around it shrinking as it cools.

Counter this by welding 25 to 50mm, then with a dolly on the back planish the weld from the outside.
Ideally the weld needs to be proud and after hammering it will then be flat leaving just a flash over with a
sanding or flap disc to finish.

So to recap; weld a bit, hammer, weld a bit more, hammer, till the weld is complete.
Welds shrink and hammering expands.

If the car is worth the time then take the time to do a proper job and enjoy the learning curve.

Paul G

nick205 - 22/6/17 at 08:04 AM

I'd favour welding new metal in as well. Your going to have to paint it anyway so go for the better job and weld in some new sheets steel.

Having practiced a little myself MIG welding thin sheet steel I'd suggest practicing off the door first to make sure you're happy with the technique.

ETA...there are some good videos on YouTube showing methods for welding thin sheet metal. I found these helpful when attempting it myself.

If there's space behind the door skin then a decent bit of copper stock (bar, block etc) will help by acting as a heat sink to draw heat away and reduce distortion. Given the photo above though I can imagine it'll be tight on space behind the area being worked on.

Also be careful when working on the actual door not to burn the timber frame

[Edited on 22/6/17 by nick205]

[Edited on 23/6/17 by nick205]

SteveWallace - 23/6/17 at 12:04 PM

Your right, the correct long term solution is to weld a new bit in.

I do need to learn to weld at some point, but, for various personal reasons I feel like I need to make some progress, so I've just given it to my local expert to do. There are other less sensitive bits that I can start my welding experience on later in the build.

Working around the wood is not a problem as I've taken all of the old wood out anyway.

The good news is that I've stripped the paint off the other door and its near perfect. The plan for that one is to spray it with etch primer to protect it, put the new wood in, and then put the hinges on so that I can use it to correctly locate the front door pillar.