Hardtop Build
In 2005, I started the build of the hardtop; Unhappily, because of my height, I could not adopt Basil Parson's simple approach, namely of having a one-piece top which followed the contours of the rear body allowing it be folded away neatly. I have scoured literature on pre-war cars, and have not found any example of such a design. I believe Basil had invented the first fold-away hardtop.
Being desperate to retain his idea, I embarked on a compromise design including a major part 'folding away', but using a targa-top design. This involves making five parts in addition to a pair of side screens with sliding laminated glass windows:-
Rear Section
Targa Top
Roof Doors (two)
Front Brow
ie. the main component consists of the rear roof section with sides and halved rear screen. This drops down on the back of the car. A front brow sits atop the windscreen pillars held in place by substantial turnkey catches. This creates a solid and (hopefully) waterproof join with the windscreen following the curved profile thereof. Both of these items have substantial tubular slots into which fit the prongs on each end of the targa-top centre piece; this joins (using over-centre latches) the front to the back providing hinging points for the upwards swinging roof doors (the car being quite low, the provision of roof doors improves ingress considerably).
There are several benefits stemming from this set up. The car can be run in a number of configurations depending on the drivers wishes/weather etc.
1. roof up with doors and side-screens fitted. This is the same as any fixed-head car
2. as above, without sidescreens (which are easily detached and stowed)
3/4. as above without roof doors (with or without side screens)
5. without targa top
6. as 5. without front brow
7/8. with rear section folded away (with or without front brow)
9. finally, all of the above components can be left behind at home (including the rear cover and even the detachable side doors) to reduce weight.
The downside to the above includes weight, problems of stowage of the detached components and waterproofing, but an upside is that there is some accessable space behind the seats otherwise lost with Basil's one-piece design..
Manufacture
The car came with windscreen pillars built into the bodywork; two brass extrusions bent to fit the sides and bottom of the windscreen also came with the car. I found a centre piece for the 'V' of the screen (Morris Minor?), so the first job was to make a brass top for the screen halves in such a way it would come apart to enable assembly of the screen.
This crucial first step was expensive and difficult; the brass extrusion from Paul beck cost over £30 having a slot for a rubber seal on the upper surface. It needed to be subtly shaped to follow the curve of the lower windscreen surround yet look even from the front. Furthermore, it had to be removable to allow fitment of the glass.
The photo shows the layout and the provision of an attachment for a centre stay (to which the rear-view mirror will be fitted).
Stainless steel corner and 'vee' pieces tapped and fitted using brass countersunk screws provide the method of removal of the top rail to allow the glass to be fitted
Next, a mockup of the hardtop in mild steel confirms that the 'concertina' design, or fastback would not be practicle (or look good either). The photo shows the first trial of the final profile for shape, fit and headroom. Having now decided upon the five-piece approach, the first item to make is the front brow. Basil had provided turnkey bayonet fittings on each pillar. A flat plate with holes for the bayonet fittings starts the process; guides for these fittings are welded in with id close tolerance. Handles from Paul Beck are adapted to fit to the turnkey bayonets along with a spring and ss washer. The spring effectively clamps the plate to the pillar but allows for a rubber separator at the final assembly stage.
Even at this early stage, two points are taken into account - provision of sun shades and the shape of the brow to ensure it does not become too large/heavy. I decided to angle it in at each side even though it would cause a lot of extra work.
Finally, another factor has to be taken into account; Basil had provided slots between the rear body and the rear mudguards for the sides of the hardtop (when folded away). These are vertical, so the sides of the hardtop must of needs be vertical. In turn, to keep the sides of the hardtop parallel to the doors below, the top of the hardtop will be as wide as the point where it fits on the rear of the body. Because the body sides and windscreen pillars slope inwards, the top of the pillars are closer together resulting in an overlap at this point of about an inch on each side. Whilst the result will look a bit strange, it actually is a throw-back to the car's donor vehicle which had a substantial overlap where the narrow windscreen and the hood top met (see photo) - this made the anomaly acceptable (just).
Because the hardtop folds away, the shape of the sides and profile are pre-defined. Next, I decided that the curve/shape of the join of the side to the roof would be best determined by the use of two heavy-section alloy tubes; these and a third centre tube would provide a combined jig and frame for the rear section. The correct bend of these tubes was another crucial point. Three 1 5/8th ali tubes were annealed in preparation for bending; each took about three hours to form using the Occold utilising a cradle. These were tacked onto the front brow and spaced at the back using a temp cross-piece. The bare shape is now apparent. The construction will be an ali frame skinned in 18g ali.
Unfortunately, also now apparent is another design problem; Basil had indicated the shape of the back of the hardtop by a shallow 'vee' pointing backwards in the bodywork. When this is translated into the back of the hardtop in the 'up' position, the backwards point/vee does not work. I made a model of this area to try to sort the problem - yes, I could reverse the vee on the hardtop and do the same on the rear bodywork, but this would entail days of extra work.
Meanwhile, here is an example of the mouthwatering cars to pass through Nick Parravani's workshop ....
No prizes for identifying the marque! ........... anyway, where was I?
One of the drawbacks of Basil Parson's idea was that the rear screen would be visible when the hardtop was down. A way round this would be to provide a cover; if I did this, it would mean that I could alter the rear profile of the hardtop without modifying the existing bodywork. Much time was invested in ensuring the front view would be even and naturally curved so as not to offend the eye. The 'ribs' were cut out using a bandsaw and welded in place. The mid ribs were angled to ensure the rear glass would fit nicely (laminated glass panels cut from a damaged Lotus Elan+2 windscreen!) Round about this time, I made the flat sides in 4mm ali plate and tacked them to the side tubes, setting them up in the vertical plane so they would fit into the spaces provided.
I was not happy with the overall look, and spent weeks deliberating the choices open to me. The main objection was that the line of the side of the back of the door did not follow into the roof (see picture). I had to make a decision - proceed as Basil had intended, or involve months of extra work modifying the body to accept sloping sides to the hardtop (also, the overlap on the brow would not be required involving a time-consuming alteration).
Decision: .... Modify to sloping sides. Rationale: ... Why spend £££ and hrs hrs hrs making the thing unless it ended up looking as well as the circumstances allow.
Stemming from this, the first consideration was the changes to the bodywork. The slots where the hardtop sides fit need to be sloped to fit the folded-away hardtop. At the same time. I needed to consider the fixings for the hardtop/cover in both positions. I decided upon two posts to be fitted to the body - see picture. These would be subject to considerable stress, so they need support from a frame under the existing body skin. The change in profile of the slots also need to be framed, and finally, as the whole rear portion of the hardtop would be quite heavy, I needed to find a way of 'wheeling' it from one position to the other. A pair of small diameter wheels would be fitted to the back of the top, but these would run on the existing bodywork - I was concerned the it might deflect under the weight, so the frame should provide for this as well as the hinge point for the cover (at the back). Four jobs to cover.
The frame before painting is shown here.
The mod to the bodywork is also shown drawn before the surgeon's hacksaw is applied..
The slope to the side and embryo post can clearly be seen here.
(the brown cardboard is the first look at the rear screen position [above] and sidescreen [below])
in the centre photo, the filler bezel may just be seen forward of the rear wing - one of the problems of the fold away hardtop is the routing of the fuel filler pipe.