Allowable repairs to body panels

[SteveW]

I've now started to work on the doors on my TC so that I can fit them to the rear door pillars and hence find the right positions for the front pillars. I need to replace the wood, so I've stripped them down to the bare panels. One of them is in a good state of repair and will only need the new wood and repainting, the other needs more work as the bottom sill is rusted and will need to be replaced, and there are a some previously repaired rust holes in the door skin.

I've stripped the paint off and sanded off the old filler (bondo) to investigate, and treated any remaining surface rust spots. My question is:

What is an acceptable way of repairing such holes in a car of this age? The holes are too small to trash the whole skin or to cut and weld (too much risk of distortion), so is modern car body filler acceptable, is there a better modern equivalent, or do the faithful demand a more 'period' repair (not sure I want to learn lead loading at this stage)? You can see the 3 holes in the picture (hinge slot gives scale)

I was thinking high quality modern filler/bondo with high metal content (e.g. Isopon metalik) ...

[frenchblatter]

Mine were much worse that that and Maurice, the French magician repaired them. You cannot use lead nowadays he used solder.

This is the side panel but the door was the same.
http://www.lotus7news.co.uk/TC13-05%20%286%29.jpeg

[SteveW]

Mine were much worse that that and Maurice, the French magician repaired them. You cannot use lead nowadays he used solder.

Just plain old solder that you would use in electrical wiring?

I guess that I wasn't really referring to real lead, but the stuff that those skilled in lead loading now use - I've seen it demonstrated at car shows, maybe it is just a big block of solder.

[XPAGnut]

People still use lead or lead/tin-- 70 lead/ 30 tin. Lead free "leads" come in numerous flavors. tin/copper/zinc comes to mind. An idea of range here: http://www.johnsonmfg.com/temp/NOLEAD.HTM

[stephen stierman]

I am sorry to give you the bad news. The only way to get rid of the rust that is perforating from the inside is to cut the bottom several inches off the door and TIG or MIG a new section in. You cannot see the area of corrosion that is hidden on the back side of that skin without taking it away from the inner flanges. It can easily be folded over to duplicate the door bottom. Proper welding will not produce massive distortion and a bit of hammer and dolly work will have the skin reasonably smooth. A skim of filler over the skin and you will have a properly repaired door. You can repair it with lead and six months later after you are waxing your shiny new paint job you will find the start of more rust bubbles coming through again. I replaced the lower bottoms of both my doors as above and they are just fine will be after I am gone.

[SteveW]

Your right. I was just trying to make some progress and was probably looking for a quick fix that I could do myself. I've just dropped the door off with a local guy with a good reputation for doing panel work and left it with him to decide the best fix, this will probably be cutting and replacing.

The good news is that I've now stripped the paint off the other door and there is no sign of rust at all, aside from a patina of surface rust on the bare metal behind one of the old bits of wood. That's now gone so the plan is to paint the inside behind where the wood goes with POR 15 and then spray the rest in etch primer to protect it whilst I work on the rest of the car. Pictures in due course.

[stephen stierman]

Hopefully Steve, that is the repair he will do for you, once done all is corrected. Much of my panel and timber work has been with Morgans. Their doors are small and quite easy to reskin as they rust in a similar fashion to the TC door. Below photo of backside of Morgan door with lower flange. This sort of corrosion is common and results in a line of bubble about an inch up from the bottom much like yours, that folks attempt to dig out and bondo or lead over. Considering that they are looking at the tip of the iceberg it always fails. A new skin and flange as needed properly painted and caulked will cure the problem.

[XPAGnut]

Leading is most suitable for the purpose of sectional repairs because it can be done to fill seams from front to back. Depending on what part of the Country or World your in, even bondo repairs for dents and minor rust through can be done in a way where the metal is "treated" to neutralize the metal or rust and when bondo applied over in the right way can lest decades. Of course it can also be done such that it will only last long enough to transfer title to a new owner.

It is much more tricky to do proper bondo repairs compared to lead repairs over rusted areas, but in over 50 years of doing body work on everyting from Model T's to $12 million Ferrari's I have seen 30+ year old bondo repairs that would have lasted forever. Repairs on rust like shown here can be done to prolong life of an original skin, but it is very tricky, and most likely only lead would stand any chance of success.

[stephen stierman]

The skin must be removed from the mounting flange and media blasted or chemically stripped in and out to stop rust, by the time this is done Steve would be dealing with lace. Yes you could lead it, but why bother when making up a section to butt weld to solid metal is so easy these day with MIG or TIG. Lead is not without its downside, without considering the safety issue, one must consider what happens if a bit of flux is left on the metal, soon it will be a bubble or two in the paint. Weld it, a bit of sanding with a disc to level the weld and maybe some hammer and dolly work and a skim of bondo, no doubt the door has plenty of dings and dips after 70 years anyway that must be tended to.

[XPAGnut]

I was speaking generally Stephen. Replacing entire steel panels on a TC has its downsize, too. Everything has a downside if you look for it.

[SteveW]

The doors are probably one of the most difficult parts to get right due to how thin the metal is, and the flanges/sills that can trap water and rust. My other door panel is in very good condition so I'm going to paint the inside of the skin with POR15 to keep it that way.

The front quarter panels will be replaced with new metal, I have three sets of rear quarter panels, on most of which the complex curves down the top of the door frames are in good condition, so the plan here is to cut these out (as they are very hard to reproduce) and butt weld new metal for the rest of panel.

The wings and bonnet (hood) are much thicker metal, so less of a problem aggressively removing the rust and still ending up with a solid panel, even if patches need to be welded in.

[stephen stierman]

Yes everything does have a downside on restoration, I would certainly agree with that.

My tub required new front and rear quarters which are easy enough to make up other than that rear one with the elbow area and its compound curves which is difficult at home for shade tree panel beaters like me. The solution to cut the curved section out and butt weld it into a new panel is exactly what I did and works just fine. If you look at the photo of my tub, it is hardly perceptible that this was done.

[TD4834]

I had some small holes in the rocker panels of my TD I'm restoring all panels removed and mineral blasted. Then the holes were metal sprayed. The metal application was then smoothed and all panels were powder coated inside and out. The powdercoat acts as a primer sealer and can be sanded and fillers applied to its surface. Once the bodywork is finished and spot coated with primer, the top coat color and clears can be applied.

[SteveW]

That's a brave decision to go with powder coating. In theory it will be very protective but I've heard a few horror stories where it hasn't bonded properly to the metal and after a couple of years its started to flake off in quite large chunks, particularly in areas that flex. Make sure that you properly seal any bare edges and holes that you create when fitting as water getting behind the powder coating is the biggest single reason for failure.