I thought I'd do a little tech piece on the last job I did on my 33 coupe. It took a bit of work, but didn't require master level skills so even I managed to do a reasonable job. The first part may have been seen before, but the last part is new. By the way, when I say bonnet I mean hood Next job was to work out how to fill the hole in the roof. At Chimay I inspected a nice 34. The owner, Simon said he filled the roof with a vinyl covered steel insert, sikaflexed in. He said he used some instructions from Kev Elliot in Custom Car, which said use a mk1 Astra bonnet, turned front to back. So using that basic idea as a guide I thought I'd give it a go, but start from first principles. Here's the roof opening with the wooden bows still intact. These are worth keeping because you tack the headlining to them. I wanted to make a template to show the curvature of the roof. I had a brainwave - That's it - use a piece of ply with screws screwed through until they just touch the metal surface, or the wooden bows. This worked really well, because each screw is finely adjustable, plus it was cheap and quick to make. I took it to the local car breakers and tried it on various bonnets. Why bonnets, I hear you say, and not roofs?? Well, two reasons, if a bonnet will do it, it's easily removed and transported, plus the cars are stacked two high so the lower roofs are inaccessible and the upper level too high. Bonnets are easy. So around I went, trying this and that, and there were only a few with an area big enough, without flutes or ridges, and only really one, that came close to the profile as dictated by my super accurate template. Mondeo. Not the early one, the later one styled more like a focus. The bonnet was a bit damaged at the front so he kindly let me have it for nothing. Here's the bonnet at home And with the template in place, though it's hard to show how well it fits. Like Kev found with the Astra bonnet, it fits better back to front. I cut through the outer skin and chopped out the inner panels. I had to carefully trim the inner panels so I could break the gluey blobs holding inner and outer together. A few pics: I then removed the gluey lumps with a chisel and reduced the residue with a scraper. Then I slung the panel on for a test fit. Not bad, not bad at all. Pretty good really. I drew around the opening from the inside and then trimmed around with a generous allowance, leaving room for a final trim. I then really studied the roof opening and worked out what I had. There is a hidem type metal band around the opening, with two screws and nuts at each corner. I removed the nuts and pried the banding out. It comes out in three parts. I removed the remnants of the canvas top material. The opening is in pretty good shape, the tacking strip seems to be ok. This is as far as I have got, for now, I have to decide exactly how to attach the panel, whether to make it temporary or permanent, and I need some vinyl to cover it. But here is a parting shot with the new lid resting in place. I don't think I could have got a better profile if I had wheeled one up from scratch. Mart. Part 2 to follow:
**************************************************************** Part 2 (After a few weeks working away from home, which gave me some good thinking time.) ***************************************************************** I had the section of Mondeo bonnet and had slowly contrived a plan on how to fit it. NealinCA posted me a pic of a hammer form panel he made for his rpu, and I wanted to do something like that for the roof insert. Heres an overall pic of the task at hand. Firstly I removed all the remnants of cloth and tacks from the roof surround tack strip. The strip was in quite good condition, pretty sure it had only had one insert ever fitted. Sourced from the local diy place. here's a strip of 15mm by 5mm steel bar, chosen as the best size to go around the opening. And using a Y-block pulley in the vice I proceeded to bend it to suit the shape of the roof opening. It was a bit tricky and took a bit of re-bending and flattening. Keep going, all the way around. It'n not as easy as the pics suggest, lots of tweaking and rebending. I had to weld three pieces together. The outer frame was then drilled in 20 places and the holes transferred to the tack strip and drilled through. I then countersunk the holes, tapped them and after turning the heads down a bit, inserted 20 10-32 UNF screws into the holes. I secured each one in place with weld and then ground the welds flat. I was then able to lay the frame onto the upturned filler panel. I then scribed a good clear line around it, and (after this pic) trimmed the panel to approx 6-7mm outside the line. Then using a mallet and a lump hammer as a dolly I knocked the overlapping piece up around the edge of the frame, the frame acting as a hammer form. (no pic sorry) Once the outer lip was formed, I trimmed off any excess and welded the skin to the frame in a 3 stage process. 1, grind a little notch. 2, Run a little bead of weld into the notch. 3, Grind the weld down flush with the surrounding metal, taking the outer skin down flush at the same time. I trialled the frame in the roof and had to drill the holes along the side rails a little oversize, (7mm) as the frame had shrunk a bit with the hammering. I got it in place with just a little bumping with the palm of my hand, and put the nuts on below. The screws need trimming down, but will do for now. And here is a quick look at how it sits. Right side: Rear: And left side: Obviously it will need to come off again for painting and to paint the tack strip area and apply some sealant, but I'm pretty pleased with it as it stands. Mart.
************************************************************** Part 3 after the initial try-out ***************************************************************** Took it off and ran a wire brush around the roof aperture. Stripped all the old paint off. Remember this was a Mondeo bonnet? Those two holes on the right of the pic are the windscreen washer jet holes, they are at the back of the bonnet but on the front of my insert. Welded them up and just licked the welds down with the grinder. Didn't bother with any filler. Two coats of screwfix red primer and one of hammerite satin black. Love the red primer, don't like the hammerite stuff. Didn't take pics at this stage, but put another coat of black on the top and the next day flipped it over and after cleaning the remnants of the glue nobules off with the wire brush, put a coat of red oxide on the underside. Cut a bicycle inner tube into long strips and made a rubber gasket to go around the perimeter. punched holes in it to fit over the studs and put little bits of tape on the corners to hold the gasket in position. I plonked the roof insert back in place and tightened it down. The rollered paint has a sort of mottled effect, and looks a little like stretched fabric. I'm quite pleased with it. It looks well made in a rough and ready way, (if you know what I mean). It looks ok from the inside too, with the coat of red paint. I may still trim a little off the length of the screws. I intend to just put a bit of matt black paint on the screws, because when driving, I find the bright screws in my peripheral vision distracting. Overall I'm pretty pleased with the way it turned out. The basic principal could be applied to most coupe tops, for a sedan you would probably be looking at roof panels from station wagons and the like, so that would be that more difficult. The 3d template would still work, though, but wiould need to be more substantial as it gets bigger. The 3d template would still work idf you were sourcing a panel to be welded in, rather than bolted in. I opted for the bolt in job because in theory at least the whole job could be reversible and a canvas insert fitted later. Mart.
This is what the HAMB is all about!!!!!! Not only is this a great TECH thread, but it also helps in conjuring up other ideas, I can already see using some of MART's ideas and using them for other projects. Using/bending the steel bar, simple yet very effective. Great work!!
Good bit of basic tech to tackle a job that would seem very daunting!!! The template is a great idea as well! Thanks for sharing.
Cheers, Lads. The template did work well, it occurred to me you could use the same technique to find a door skin parch panel - make a template, find a panel at the breakers that matches that little piece, could be a door, hood, or quarter - as long as it matches the profile and is bigger than the part needed it would work. Mart.
Great work Mart,this just proves there is yet another way to have a nice looking top without going into debt! HRP
Great idea and it looks real good. Well done tech. Cheers. (P.S. - it will always be a bonnet, not a hood - Haha)
I believe it was a sort of thin material underlayer, cotton or muslin, someone may be able to say exactly, then a cotton padding type layer, then a sort of rubberised canvas top material, all tacked into the tack strip around the roof aperture, then the edge covered over with the finisher strip tacked down and a couple of bolts through at each corner. The finisher strip hides all the bolts and tacks, they're pretty small. Mart.
The manufacturers had soft tops until the mid 30s. Because no steel mill had a rolling mill that could roll sheet metal wide enough to do a complete roof stamping. Then around 1935-36 sheet metal was available in wider widths. From the heart of steel mills, Pittsburgh Ago
Thanks Mart, brilliant tech. Don,t know how I missed this, will be doing a similar thing here once I ,ve chopped my top and rebuilt the channel around the opening.
Thanks for the tech post on this. After reading this a while back I decided To try it. I made this one today . I used the top from a 59 Belair.
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