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crispy roof fun part II: the return


 
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jejoenje



Joined: 20 Aug 2016
Posts: 726
Location: Alloa, Scotland

PostPosted: Sat Sep 05, 2020 19:40    Post subject: crispy roof fun part II: the return Reply with quote

Hello!

As reported earlier, I am needing to re-visit previous repairs to Selma's roof.
The panel bond I used to fit a replacement steel section (essentially the part above the front seats, where the sunroof used to be)
had started to lift on one side, just above the driver's seat. This exposed bare metal (needed for the 2k epoxy I used), and rust had
come in with a vengeance.

Anyway, my original plan was to fit yet more fresh steel, but weld it this time, but to be honest I was never comfortable welding thin steel,
especially where this has to be essentially waterproof, the need for bare metal would mean likely rust coming back, etc etc. Basically, I'm
just really really tired of this particular issue, and would like to have a more permanent solution.

So, I would be interested in some opinions on the following (more or less mad) plans...

After I'm done cleaning up whatever rust has reappeared, two options (leaving aside welding, as per above) have come to mind -

1. Essentially make a fibreglass "lid" for the entire front section of the roof (above the front seats).
I'm thinking I would be able to use the existing roof as a mould, laminating a fibreglass "shell", before lifting this off, potentially
strengthening with more fibreglass mat, trimming, painting. A little bit like this.
I'd then cut out most of the steel (front section) roof, leaving a "lip" a couple of inches up from the gutter and the windscren, as
well as (obviously) the cross brace at the back end. The fibreglass "lid" would then be bonded in and either bolted or riveted in
place, to the steel lip - much like a camper top.
Pros:
- no more steel, and hence rust, to worry about. I'm hoping that would be the end of it. Relatively easily "patched" to if repairs
are needed.
Cons:
- I'm not super confident of the bonding, particularly at the back, where it would sit on top of the cross brace. Any issues with
bonding there, and there would be annoying leaks which is kind of what I was trying to avoid in the first place.
- I'm also not sure how well I would be able to hide any rivets or fasteners; worried they may be fairly obvious in the front, just above
the windscreen.
- Similar to the last point, I'm worried there would be too much of a prominent edge, or lip, where the fibreglass sections sits on to
the metal, and that it would be hard to hide/make this look "okay", particularly above the windscreen.

2. Vinyl "wrap".
Basically just make sure I get rid of any of the rust that is there (doubly sure), and then cover the lot (possibly including the back
section of the roof, between the crystalites, with some form of good quality vinyl.
Pros:
- Could be a pretty quick solution.
- Should keep any moisture/air out so hopefully no more issues with rust from the outside.
Cons:
- I've never vinyled anything in my life... and am somewhat concerned about looking like a boy racer!  Shocked
- Wouldn't be able to paint this, I don't think, and I was hoping to use the same truck bed liner (Raptor Liner) that's already
on the rest of the van.
- Obviously entirely reliant on the existing structure. In the long term, I would still be worried about rust slowly "eating" what's
underneath, even if I do my best to take out what's bad now. In effect, I'd be worried about this storing up more problems for the
future, rather than saving myself from it, which kind of defeats the point...?  Rolling Eyes

Thoughts?  Very Happy

PS. I should say, although I want this to look nice, I don't ever plan on selling the van (she'd have to be pried from my cold dead
hands - or more likely I will be breaking for parts!), so not concerned about value to others as such. That ship has sailed!  Smile
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PostPosted: Sat Sep 05, 2020 19:40    Post subject: Google Ads keep this community free to join!


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andyman



Joined: 08 Dec 2012
Posts: 4771
Location: Penrith, Cumbria

PostPosted: Sun Sep 06, 2020 10:24    Post subject: Reply with quote

Before I start recommending solutions, 2 quick questions.
 1) How did you hold the new roof section(s) down while the panel bond was setting, and subsequently prevent it from cracking apart?
 2) How did you eliminate all moisture from the joint faces before/during bonding?
My experience of fibre-glass bonding to metal (mainly cleaning up and filling rusty holes in car wings, where the underside is going to be exposed to road spray) is that it is just a matter of time before the rust comes through again, - the lip below my Deli's rear window is an example, although removing the window first might give better results.
I once had a Bond Equipe. this car had a sports fibreglass body, bonded to the steel floor-pan, scuttle and windscreen of a Triumph Herald. I was constantly trying to seal the cracks between fibre-glass roof and steel windscreen frame. The Herald and Equipe both suffered from the scuttle-shake inevitable on chassis-mounted bodies, just as L300s tend to suffer from slow idle body vibration, which will crack any hard/brittle bonding material (as we see with the original panel seal mastic in the scuttle front seams; the welds don't crack, but the aged mastic does.)
At this stage, my suggestion would be for removing the first repair plate, cleaning thoroughly of all rust on the lip to which the new plate must be fitted.
Ensure the metal lip is clean and dry before applying acid etch primer which bonds better to fresh steel than ordinary primer.
Make a new plate from thin, galvanised sheet with around 20-30mm overlap, dry fit it, holding in place with 4 fittings (screws or pop rivets), while you drill the other fixing holes. Put each of these first 4 fittings half-way along each side, not at the corners.
Then remove the plate, apply a generous bead of rubber (not silicon) mastic, following the line of the pre-drilled holes, and final-fit the panel, rolling or pressing down the panel between rivets or st/steel screws to squeeze out any surplus mastic and prevent scalloping of the edge. Tidy  and smooth the mastic around the panel, and underneath, if reachable. To this end, it is a good idea to ensure no burrs on the edges of the panel or roof lip. It may even be worth making a template of the panel, and getting the sheet cut with a guillotine to prevent distortion. Any pin-holes outside the main area can be cleaned and filled with the mastic, using a blob of it on the sticky side of masking tape, having slightly dished the hole with a suitable punch. When the mastic is dry, and you pull off the tape, you should have a smooth, level fill. The raptor paint or similar should be applied over the sealant/adhesive after giving it a few hours to dry. Sika Stixall and CT1 Construction adhesive have the right characteristics of vibration-proof flexibility and paintability that you need.
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andyman



Joined: 08 Dec 2012
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PostPosted: Sun Sep 06, 2020 10:31    Post subject: Reply with quote

PS I have a dry barn with lots of kit where you could do this, if you brought your (pre-cut?) panel with you.
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Lewis
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PostPosted: Sun Sep 06, 2020 11:15    Post subject: Re: crispy roof fun part II: the return Reply with quote

jejoenje wrote:

2. Vinyl "wrap".
Basically just make sure I get rid of any of the rust that is there (doubly sure), and then cover the lot (possibly including the back
section of the roof, between the crystalites, with some form of good quality vinyl.
Pros:
- Could be a pretty quick solution.
- Should keep any moisture/air out so hopefully no more issues with rust from the outside.
Cons:
- I've never vinyled anything in my life... and am somewhat concerned about looking like a boy racer! †Shocked
- Wouldn't be able to paint this, I don't think, and I was hoping to use the same truck bed liner (Raptor Liner) that's already
on the rest of the van.

- Obviously entirely reliant on the existing structure. In the long term, I would still be worried about rust slowly "eating" what's
underneath, even if I do my best to take out what's bad now. In effect, I'd be worried about this storing up more problems for the
future, rather than saving myself from it, which kind of defeats the point...? †Rolling Eyes

Thoughts? †Very Happy

PS. I should say, although I want this to look nice, I don't ever plan on selling the van (she'd have to be pried from my cold dead
hands - or more likely I will be breaking for parts!), so not concerned about value to others as such. That ship has sailed! †Smile



If I remember right you can get vinyl wrap printed in any colour you want, so that saves painting.
Note though that if there is anything under the vinyl that can rust it will and once it starts bubbling up it will stick out like a sore thumb.


There is a company, in Knottingly, Nr Leeds, called Euro Motor Campers, who made their own roof moulds for various models of vehicles
They may already have one for yours and be able to supply you a ready built roof.

I used to have a Mercedes 207D that had been converted from a greengrocers van - It was in fact the vehicle I part ex'ed for my first Deli.
I'd had it for about 10 years and went to them to see if they could do a roof repair for me. The owber laugh and took me back into their
waiting room and pointed to a photo on the wall, one of many dozens in a frame.
There on the edge of the frame was my campervan. They did the original conversion. †Laughing
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jejoenje



Joined: 20 Aug 2016
Posts: 726
Location: Alloa, Scotland

PostPosted: Sun Sep 06, 2020 20:09    Post subject: Reply with quote

Thanks gents!

Andy;
andyman wrote:

1) How did you hold the new roof section(s) down while the panel bond was setting, and subsequently prevent it from cracking
apart?

I held it in place with some stainless self-tapping screws, which I later ground down. You can just see them in this photo (I think this was the "dry" fit without mastic).
I think you've hit the nail on the head though, with that comment and a couple of other things. It's only really one side (drivers side) of
the replacement panel that had started to "lift". I think this was because the panel slighly deformed when fitting to aperture (because it
has to curve slightly in several directions, even on the section of the roof that appears to be flat), slightly pulling upwards on one side.
Although the screws will have helped somewhat, clearly not enough.

andyman wrote:

†2) How did you eliminate all moisture from the joint faces before/during bonding?

I think again this may have been part of the issue. Although I was pretty careful to clean everything up very thoroughly, the 2-part epoxy I used needed
(or so I was told) bare metal to adhere properly. Obviously as soon as anything had started to lift even slightly, corrosion set in immediately.
Unfortunately I've now repaired the section that had rusted (using fibreglass as a temporary solution mostly) and I forgot to take photos, but essentially
I had to cut a substantial bit (a strip about 2 inches wide) out, which essentially was the overlap between the old and new steel.
I'm now regretting using that 2k epoxy stuff - it was very expensive, but I think other forms of similar adhesive PU sealant would have done just as good
a job, and possibly would have been a bit more flexible!

okay, your suggestion of replacing the patch with new galvanised steel - I would love to!  Smile Steel would be my preferred option!
However, because of the above, unfortunately the section that would now have to go extends down the curve of the roof on the sides, towards the gutter.
Part of the reason I started thinking about fibreglass, is that I would be able to shape this relatively easily and accurately to the contour of the roof. In
part, this is why I chickened out of welding, as I would have to basically quite accurately shape any patch that would go in.
Someone handier (and more patient!) than me with hammer and dolly would be able to do it I'm sure, but my DIY skills aren't up to that sort of metal trickery.
Before, I was careful to stick to the more or less flat section of the roof in terms of repair plate (again see the photo linked above for what I mean), so I didn't
have to worry about much of a curve.
Fibreglass, however, I could conceivably mould and shape on top of the existing roof, and I reckon it's at least a little bit more flexible than rigid steel sheet,
so I may have fewer issues making it conform to whatever aperture it has to cover.

I should also add that I certainly wouldn't be trying to bond fibreglass to steel directly; as in relying on whatever resin to bond to the steel. I think you're
dead right that would be asking for trouble down the line!
What I was thinking is treating the fibreglass "top" much as you were suggesting with the galvanised sheet - hold in place with some sort of (probably
permanent, actually) fasteners, and further bond it in with some form of adhesive sealant, for waterproofing.

It's interesting you stressing not silicone mastic - I tend to use Tigerseal... not for any reason, just because I am familiar with it and can find it easily.
Would Sikaflex be better for this sort of job?

andyman wrote:

PS I have a dry barn with lots of kit where you could do this, if you brought your (pre-cut?) panel with you.

Thank you! That's very kind. Perhaps I will take you up on this at some point. A dry indoor working space is one thing I would really love - I was cursing
at the showers on saturday, seconds after I put some paint on!

Lewis wrote:

If I remember right you can get vinyl wrap printed in any colour you want, so that saves painting.
Note though that if there is anything under the vinyl that can rust it will and once it starts bubbling up it will stick out like a sore thumb.

Aye, yeah, that's my worry. To be honest, tempting as it sounds in principle, I have a hunch that it may just very quickly lead to more problems.
It just feels like it's covering the problem more than dealing with it.

On the whole, at the moment, having now repaired the major rust areas, I think I'm going to sand the whole roof and re-paint with some 2k epoxy mastic
primer, and see how it goes. Perhaps the other bonded sides are going to hold for longer.
I may still work towards at least making a template of the front section in fibreglass - no need for actually cutting a hole yet, and at least I can see if I can
get something made that looks half decent...
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jejoenje



Joined: 20 Aug 2016
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Location: Alloa, Scotland

PostPosted: Sun Sep 06, 2020 20:10    Post subject: Reply with quote

Sorry I have no idea what's going on with the blank lines in the above reply!   Sad
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andyman



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PostPosted: Sun Sep 06, 2020 23:23    Post subject: Reply with quote

I don't know if the photo shows the total number of rivets and screws finally used, but unless you were sealing underneath with a flexible sealant, that spacing looks too big by a factor of 2 or 3 or more. When I have filled over pop riveted patches on cars in the (long distant) past, the rivets have been spaced at 60 - 80mm. Admittedly with no epoxy to bond the patch on.
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jejoenje



Joined: 20 Aug 2016
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Location: Alloa, Scotland

PostPosted: Mon Sep 07, 2020 9:48    Post subject: Reply with quote

andyman wrote:
I don't know if the photo shows the total number of rivets and screws finally used, but unless you were sealing
underneath with a flexible sealant, that spacing looks too big by a factor of 2 or 3 or more. When I have filled over pop riveted patches
on cars in the (long distant) past, the rivets have been spaced at 60 - 80mm. Admittedly with no epoxy to bond the patch on.


Huh. Interesting. That's definitely a lot more fasteners than I used - yes I think that was the final number.
Really only intended to hold down while the epoxy cured. I checked and it was Pliogrip structural 2k epoxy panel bond, I used.

I have realised I need a second Delica.

This is because I have now realised that because I really want to use it, I am loathe to have the van off the road for repairs for long
periods of time, and obviously  Rolling Eyes that's the only reason that's keeping me from sorting this out properly, taking as much time as I need...  Laughing
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Lewis
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PostPosted: Mon Sep 07, 2020 10:23    Post subject: Reply with quote

jejoenje wrote:
Sorry I have no idea what's going on with the blank lines in the above reply! † Sad



Do you mean the first post ? †hmmm

That can happen when you use a phone to do things.  Would you like me to edit it for you ?
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jejoenje



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PostPosted: Mon Sep 07, 2020 10:54    Post subject: Reply with quote

Thanks Lewis - no don't worry. Weirdly enough it came up with loads of blank lines when I first looked at the new post, and then they disappeared after a few "refreshes".
Ghost in the machine I suppose. All good.
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