Lotus Elan

Another post about stress cracks

PostPost by: JonB » Sat Mar 24, 2018 7:48 am

Hi all

I recently mentioned that I had discovered stress cracks in the driver's side A pillar of my Plus 2. As it is an S130/5 the roof and pillars are done in a very coarse metal flake which I believe was applied at the factory in the gel coat. So what I am looking at on the roof is the original finish, applied over 45 years ago.

I have also read that it is difficult to recreate when repainting a car, due to the shape / coarseness of the flakes.

So... stress cracks appeared on my A pillar but they are not very noticeable. However, they are cracks and as such I would expect water ingress to the fibreglass below the gel coat. I'm not planning to repair them any time soon, but I do wonder if I should attempt to seal them with some of Captain Tolley's Creeping Crack sealer.

In case you haven't come across this stuff before, it is a milky fluid with a water-like consistency, used in the boating world to seal hairline cracks around portholes and other openings. I've used it to seal some leaks on my Elan, and it is invisible when it dries. It is supposed to leave a flexible seal, and because its viscosity is so low, it gets drawn into cracks by capillary action.

The question is, should I use it to keep water out of my stress cracks, or is it likely to cause further damage?
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PostPost by: nmauduit » Sat Mar 24, 2018 9:33 am

I don't think metal flakes would have been included in the gel coat. If when sanding the metallic paint you go straight to the fiber without finding the gelcoat surface first, it most likely means someone have removed the gelcoat on a prior respray and painted on the fiberglass without replacing the removed factory gelcoat.

As for stress cracks, books have been written about that but my first thought is that the cracks go far below the gelcoat, and that is the main problem. This creates a mechanical weakness, which is only cured by a mechanical solution. If one wants to delay the time consuming application of a durable solution, I would keep the car in the dry as much as possible, and not apply any funny product which may be a contamination further down when the time comes for a proper repair (no greasy, water repellent silicone etc, maybe some coats of clear to seal from the top - though since the fiberglass is fractured it will soon move more than the clear coats will be able to stand).
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PostPost by: JonB » Sat Mar 24, 2018 10:01 am

nmauduit wrote:I don't think metal flakes would have been included in the gel coat.


Comments on this thread seem to disagree with you: lotus-chassis-f36/silver-metalflake-roof-t31926.html

Particularly this one:

chrisban wrote:I had a conversation with a Lotus employee some years ago about factory metalflake which suggested that it was very hit and miss, being applied at the shell moulding stage in the Gel coat. If it looked good when the shell was turned out, it stayed. If not, it got sprayed over. So some cars have a guilty secret hiding under their original paint. Also some customers requested that the car was whole colour, and again the metalflake was hidden.
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PostPost by: Orsom Weels » Sat Mar 24, 2018 10:05 am

nmauduit wrote:I don't think metal flakes would have been included in the gel coat.


I can assure you it was ! From what I have learned from talking to guys who were laying the shells up in the moulds at the time, they experimented with different methods, & found it was much easier to get a uniform finish by adding it into/onto the clear gel coat as it was applied to the mould.
When I stripped my own +2 back to bare grp, there was evidence of metal flake particles in the gel coat all over the tops of the wings, fading out to nothing further away from the roof.
The finish can be reproduced but getting hold of the correct grade of aluminium flake is not easy now. It's added to lacquer & then sprayed on using an appropriately set up spray gun. I did mine back in about 1988/9 & it now needs doing again, as years of polishing has exposed the ally flakes to the elements & they have tarnished to more of a gold in places.
Jon, as for your cracks, as nmauduit says, I would be careful about filling them with anything that may cause problems further down the road when you come to doing it properly. Clear lacquer shouldn't do any harm in that respect, although to be fair, IF done properly at a later date, they should be well ground out which should remove any trace, as long as whatever you choose to use doesn't have a negative effect on the remaining sound grp.

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PostPost by: nmauduit » Sat Mar 24, 2018 11:35 am

Orsom Weels wrote:
nmauduit wrote:I don't think metal flakes would have been included in the gel coat.


I can assure you it was !


it is going to be quite difficult to restore identically then, considering the trouble to spray gelcoat to begin with, adding homogeneously spread and adequately oriented layer of metal flakes is going to require quite a bit of experimentation...

An other good reason to keep the original finish then if one is inclined to preserve originality : it maybe worth looking into reinforcing the fiberglass from the inside before topcoating clear to preserve it from humidity, depending on where and how the craks are set (probably not a long term solution as the cracks will keep wanting to extend from where they have opened, but if there may have been a singular initial cause, bump, push on the roof etc maybe some reinforcement would prolong the quick fix some) ... good luck !
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PostPost by: nmauduit » Sat Mar 24, 2018 11:40 am

Orsom Weels wrote:
nmauduit wrote:I don't think metal flakes would have been included in the gel coat.


The finish can be reproduced but getting hold of the correct grade of aluminium flake is not easy now. It's added to lacquer & then sprayed on using an appropriately set up spray gun. I did mine back in about 1988/9 & it now needs doing again, as years of polishing has exposed the ally flakes to the elements & they have tarnished to more of a gold in places.


The issue would be the very high viscosity of gelcoat, plus when originally sprayed the body would be upside down which will have an impact on flake orientation and settling with respect to the outer surface... Cleary out of my league.
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PostPost by: JonB » Sat Mar 24, 2018 4:47 pm

Quick picture..

img_4618.jpg and
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PostPost by: nmauduit » Sat Mar 24, 2018 5:47 pm

If that is the only crack on the flaked area, chances are it came not from driving the car but from someone pushing is by the windscreen frame door opened or without the door, pinching the fiberglass profile of the post : you may then try to reinforce it from the inside, closing the crack by maintaining a slight opening force the profile from the inside and glassing it closed as a beam (e.g. on top of a cardboard roll, cf. shop manual). Then some clear would seal the flaked external layer.
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PostPost by: JonB » Sat Mar 24, 2018 7:29 pm

Good call.

Seems to me that the A pillar is weak and reinforcement might save my beck one day. You never know...
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PostPost by: 10kph » Sun Mar 25, 2018 11:40 am

Hi,
For strengthening roof posts may i suggest using carbon fibre bonded to the inside. I used some 8mm rods cut to length and bonded with resin and glass.to my Gilbern Invader some years ago. If you check a good fibre glass supplier then you will find a selection of rod and tube from 3mm upwards........you will be amazed how cheap they are.
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PostPost by: andyelan » Tue Mar 27, 2018 5:59 pm

Hi Everyone

The correct Metalflake for the roof can be obtained from www.metalflakecorp.com the reference number being 011018 Micro #1 Silver. They are a US company but will ship internationally although this does make the product rather expensive.

Instructions for mixing and applying the flake are given on the web site and are pretty much as Tim, Orsom Wheels says. One point I would make though is that although the common rule is to apply silver flake over a silver base, this is in fact incorrect as the base coat Lotus used was white (the gold roof of the JPS I believe was over yellow) which does make quite a difference to the finished appearance.

I personally wouldn't be too worried about the cracks in your roof pillar. Over a really long time they may cause some deterioration but my car has cracks and it's over 40 years old and I don't see any reason it won't last another 40 years. Generally it's only the appearance that's marred, not like on a steel car where chips through the paint really are a problem if not attended to

Regards Andy
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PostPost by: JonB » Wed Mar 28, 2018 10:30 am

When Andy (Spyder) saw the car, he commented on how particularly well done the roof was, in terms of the look of the silver flake. He thought it had been resprayed at some point (the roof, that is) and what we could see was not the original "in gel coat" application that was performed at the factory. Interesting, and I was pleased!
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