stiffening saggy 69 devon pop-top

[baj25]

I took my pop top off yesterday to fit a new skylight (69 Devon). The pop top swap is easy enough, but while I am at it I want to stiffen up the roof. When on the van it looks like the middle sags by about 50mm and a lot of water pools in it. So, the q’s- What did Devon build into the fibreglass to provide stiffness? I’m planning to fibreglass 20mm square aluminium sections front-back next to the original stiffeners, any other suggestions/experiences? TIA, Brian

 

[BJ1]

The top of the Devon roof is not fibreglass. It's a single alloy sheet stiffened underneath by alloy crossmembers that are riveted on to the roof. If yours is sagging in the middle it usually means some muppet has been sitting or standing on the roof and bent the crossmembers. Fairly easy to sort - just carefully remove the headliner inside the roof, take out the centre supports by drilling out the rivets, find some alloy extrusions of around the right size, bend them to a slight upward curve and rerivet them on - I've used greenhouse glass support bars to do this.

A couple of tips
Use proper blind rivets - they have a blanked off end to stop water getting in. I used monel aircraft rivets, but only because I have a friend who gets them free Put a dab of PU7 seamsealer on each rivet as you put it in.
Renew the seal around the outside of the alloy part of the roof .

 

[baj25]

Mmm. Now I am puzzled. Mine is definitely fibreglass. It certainly looks contemporary with the rest of the van. Any info gratefully received. Bri

 

[ozziedog]

There is a great rebuild thread on these over on VZI somewhere. If yours is definitely fibreglass the early Devons had a fibreglass seperate shroud around the perimeter that stayed on the roof while the pop top went up. There is also a fbreglass repair cap that may have been fitted over the top of the existing one, or it could be a later model fibreglass roof that Devon had after about 76 and these are much more sleek and work far better and usually have a two or three tone brownish bellows / canvas. The design of the early Devons involved a fibreglass shroud / skirt type effort with a 4 to 6 inch flat top with a one inch upstand that the bottom of the canvas fitted to. The actual pop top had an angle iron type alloy outer frame with rounded corners with a flatish alloy plate for the roof fitted to slightly bowed up strengtheners that usually sag over time. The outer angle iron type section was joined to the flat bit by a rubber gasket that meant the water had to get to half an inch deep before it ran off, or just seeped through the rivets, they have been a source of leaks for more time than they have been dry in general :roll: If you could pop up a piccy, that may help us decide what is what :mrgreen:

Ozziedog,,,,,,,,,,,,, :mrgreen:

 

[baj25]

Photos of roof as requested, inside and out. The bellows/canvas is detached at the moment, but it is white with windows in, not stripey. Cheers, Bri

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http://i156.photobucket.com/albums/t38/baj25/IMG_4995.jpg" onclick="window.open(this.href);return false;

 

[baj25]

try to put pics directly in this time...

 

[Happystamps]

i could be wrong, but....
http://www.justkampers.com/shop/t2-bay-window/original-parts/elevating-roof-parts/deluxe-devon-roof-cap-shipping-restrictions-apply-to-this-product-please-check-before-ordering-j11671.html" onclick="window.open(this.href);return false;
it looks to me like someone's replaced your devon roof with a bond-on devon roof cap.

 

[baj25]

Now that is an interesting thought. Are those caps meant to be installed without the original roof to support them? It looks like it was done a long time ago, the skylight I took out had a 1971 date stamp and the screws had completely rusted away. The headlining under the roof looks contemporary with those in the ‘fixed’ parts as well. Current thinking is to fibreglass a steel frame from 20x20 hollow section to the underside, it will add about 6kg of weight I think. Thanks for that, bri

 

[BJ1]

God knows what that is - but it looks like someone has fixed a JK-type roof cap in place of the original roof and then glassed in some wobbly supports underneath. You will need better supports to stop it sagging - perhaps bigger than 20 X 20, maybe that's big enough. Might be worth taking the bus to your local boatyard - they often do this sort of reinforcing work and may give you some free advice.

 

[ozziedog]

I reckon someone has done what they said above and added the original skylight at the same time. So it`s worked for a while and with a little more stiffening may have lasted even longer all said and done though ,,,,, fairly ingenious :mrgreen: So how is it attatched to the struts then ????????????? I`d play with reinforcing it for a while :mrgreen:

Ozziedog,,,,,,,,,,,,, :mrgreen:

 

[baj25]

Thanks for info. I fitted a 20x20 steel hollow section in a sort of H shape under the roof yesterday, fixed in place with fibreglass bandage. It has stuck (so far) and the roof is much flatter. The original ‘stiffening’ in the roof turned out to be made of out of date crunchie bars and rolled up daily mirrors, let’s say materials with young’s modulus on the low side… Some of the original mod to the roof is actually quite good, to the point that I thought it was devon original. Z profile galvanised sections have been glassed in around the edge to fix the headlining and bellows to, and it is a neat job. What I guess are original plates on top end of support arms fix with screws to the underside of the roof. I only started out changing the skylight, that’s vans for you I guess. Next job, disc brake conversion or decorating the hall/stairs/landing… Ta again, bri