A Racing bonnet

The bones of the bonnet (or hood for our American friends) are now in place and it finally looks like a car. The bonnet looks much longer than i was expecting which is a good thing and I am really rather pleased with the overall look.

On the passenger side above the chassis, there is a fixed panel that fits beneath and slightly around where the exhaust manifold will exit the side of the car. The bonnet overall is center hinged so on that side, the bonnet closes down onto the top of the panel slightly above the exhaust, you can see the exhaust opening quite clearly in the picture below. The green colour is created by the protective film over the aluminum sheet and will of course be removed. The lower panel will have a long row of louvers cut into it to allow hot air to escape out of the bonnet area. The final 300mm or so of the bonnet is 0the passenger foot-well so that area will not have any louvers in an attempt to limit rain water being blown onto your feet.

Along the top of the bonnet you can see a row of vertical pins. These are temporary clips designed by the aircraft industry to hold metal panels in place during the construction phase and are holding the panel to a big brass hinge. They will be removed and replaced with some nice brass rivets.

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The drivers side of the bonnet is effectively double hinged. It uses the same central hinge as the passenger side but it also has a hinge part way down the side that enables it to fold up against itself. In the picture below the lower part is not yet fitted as we were mocking up where the various bulges need to be to accommodate protuberances.

  1. The large oval on the left needs to be there to give sufficient space for the drivers foot to operate the throttle. The car is narrower without the overhanging saloon bodywork so the pedal is hard up against the side of the bonnet and is also quite close to the brake pedal. This is not a car for anyone with big feet or wide shoes! The bulge simply creates space for your right foot to operate the pedal through its range of movement.
  2. Moving forwards, the double oval is where the 2 carburetors are. The front carburetor would be  hard up against the side of the bonnet so it needs space to allow an equal airflow. This bulge will have an opening at the front to let cold air flow directly to the carburetors. To the right of this bulge will be 3 louvers cut facing forwards to let more cold air in. A common feature in vintage race cars
  3. Below the carburetor bulge will be a row of louvers to let hot air OUT of the bonnet area

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Below you get a better view of the central hinge. There will be a row of louvers along each side of it, the primary function of those particular louvers is of course to allow the escape of hot air, but it is more for the aesthetics – i.e. it is more sporty.

In the photo also  visible is another of my design features – the rear bonnet curve has a wider radius than the front. The Riley saloon cars had that front tight radius all the way to the back which made the bonnet flat on the top and somehow more square looking. I wanted graceful curves everywhere but naturally I still had to match the shape of the radiator hence the transition from small radius to wide.  I think the Artisans have accommodated my request rather well – its a very smooth transition.

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There was not enough room in the workshop to take a photo but when viewed from the side, the car looks nicely proportioned, looks as it should and is very definitely a sporting four seater. In a  week or so the construction work should be complete only requiring the finishing of panel fit, smoothing edges etc – then its back home for the rest of the build. The blog will slow down at that point whilst i save up money for the parts…

Firewall and bulkhead

The pace of the build is not letting up. The petrol tank is now almost complete and all the seams etc are beautifully welded together, the only items left to do are the mounting straps and the final placing of the filler neck. The filler cap itself will wait until the rear wheel mount is welded on and the TWO spare tyres are in position. In the picture below you can see the spare wheel and the petrol tank being mocked up prior to fitting. The filler cap obviously needs to be accessible but it does not need to be sticking out as much as the second photo shows.

In the top picture, note the rear of the bodywork curving above the spare wheel subtly, I am really pleased with how that worked out – somehow it makes the car look more sporting as do the rear wings presenting quite a lot of vintage rubber tyre.dsc_0131img_2946

Moving to the front of the car, the bulkhead is temporarily fitted as is the firewall. These were not fixed into position until I had sat in the car and we had agreed the maximum and minimum height of the steering wheel. Interestingly the throttle pedal  sticks out the side of the car so we talked about how the ‘bulge’ around my foot will look because it will be in plain sight when viewed from outside the car. Although this sounds a little strange, it is quite normal for vintage sports cars to be ‘fitted’ to the driver. Take away the expansive saloon bodywork and you are left with not much foot room so its fairly common to have bulges in the bodywork shaped around the driver. Plus i think people in the 1930’s were a lot smaller than we are these days.

Below is the first real chance to see the interior (minus the transmission tunnel). It is so much cleaner now with the handbrake moved to outside and the gear lever is on the steering column so there is nothing else in the middle. What you see is what there is. The gearbox cover has been designed to be left visible to passengers. I will probably only fit carpet to the wood floors.The side panels will be trimmed in a simple manner as befits the intended use of the car.

What was pleasing today was finding that getting into the drivers seat from the passenger side was really easy, you merely climb over the side, sit in the seat then swivel your legs under the steering wheel. All i have to do now is work out how to get into the seat from the drivers side. Getting out of the car was also easy, the bodywork easily supported my weight as I lifted myself up, out of the seat so many of my fears of struggling due to a lack of  strength in the body-frame have been diminished. Before the strength was only a theory but now it is clearly a reality. Joy.

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Above you get a better view of the firewall and foot-well – all of this will be visible when the bonnet is open but this area is not yet complete. The bonnet now needs to be temporarily fitted so that all the constituent parts can be matched together. So that is the next step – a plain bonnet will be built, then all the louvers, bulges, cutouts etc will be added later.

Meanwhile and less visible to this blog, the fuel tank support frame, straps and mounts are all under construction. I am rather lucky that I have had the time to visit the workshop twice a week, otherwise I would have missed a lot of the build.

As Toad of Toad Hall would say…. ‘poop poop – exciting times’

Passenger area completed

The main tub is now pretty much complete with the outer skin  welded to the bottom of the frame, rolled over the top tube and generally cleaned up. I am rather pleased with the result, the body is full of subtle curves and the lines flow beautifully around the top in a seamless fashion. It is hard not to run your hand along the top rail. To me this 4 seater touring body looks very clean yet has a decidedly rakish feel about it. Thank you gentlemen for transforming my vision into a reality!

In the picture below, you can see the beginnings of how the aluminum is rolled over the top tube and is slowly beaten into shape, it requires shrinking the metal in some places, stretching it in others and much hammering. The metal is annealed first to soften it and over time it will go hard again. The soot marks are the first step of the process, further localised heat is applied burning off the soot which is used as a tell tale to show where the annealing process has been completed.

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Below is the finished cowl beautifully smoothed and welded into the adjacent panels, also tucked over the front part of the frame which will form part of the bonnet shut which has yet to be constructed.

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And here it is the completed passenger area. The tube seen spanning the middle of the tub is temporary whilst the skin is formed, it is providing additional rigidity to the space frame during the process and will be removed shortly.img_2932img_2935

The next steps are the instrument panel supports and the main bulkhead which will close off the area between the engine and the passengers. This will consist of a firewall panel, close to the engine, a closed in ‘shelf’ for purposes yet to be decided and the actual bulkhead. There were a few design decisions made at this point but in general the Artisans are back on home ground, the bonnet will be created with influences from numerous race cars but none of the features or the construction will be totally unique. It will merely contain all the features that I think the car needs.

The exhaust is one of those design decisions. Traditionally many works sports-cars utilised a tubular exhaust manifold exiting straight out through the side of the bonnet which then ran down the side of the passenger area (hence why there are no doors) or it could follow the normal under the car route. No prizes for guessing my choice. I am not entirely sure why vintage race cars had the external systems other than perhaps to try and keep the flow of exhaust gasses as straight as possible for improved flow but it is a common feature and one that i wanted.

Luckily at the side of the workshop was the exhaust system from the Artisans supercharged Bentley ‘The Dreadnought’, so I borrowed it to see how such a system would look before they bent any metal in anger. It should be mentioned that the tubing in this system is noticeably fatter than will be used on my car and it will be a little lower down but you get the basic idea. It will of course be wrapped with insulating bandage because it will get warm and cooking passengers is not the idea.

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It is fabulous witnessing the birth of a sport-car 🙂

Bodywork skin part 2

The cowl in front of the driver has been completed but like the rest of the bodywork, not yet fitted. In the pictures below you can see the transition from a loosely shaped piece to the fully formed shape. At one stage the panel is quite clearly hammer formed then smoothed out by the English wheel.

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It still looks a little strange for a moment because there is around 3″ of spare material that will at a later stage be formed around the tube, for now you will have to image that there is no 2nd slope in the cowl…

Bodywork -skin part 1

The body-frame is now fully welded and the joins made smooth. Unfortunately for the Artisans, their TIG welder (Tungston-inert-gas) decided to malfunction preventing them from completing any further welding of the strengthening fillets / trim plates – a new trigger head is on order which will see them underway again shortly.

Clearly the body-frame is the time intensive part because its shape dictates everything about the look of the car. It has to be just right, the aluminum outer skin can only take on the contours of the frame it cannot make up for any errors created by a bad frame. However now that it is only being strengthened, rather than waste time, they shifted attention to initiating the actual bodywork. A lot of the passenger area (lets call it – the cockpit) is almost flat metal. I say almost because there is not too much of it that is actually flat, most of the panel work has a curve somewhere but only the back of the cockpit and the cowl in front of the driver requires complex curves which will be achieved with an ‘English wheel’.

Below you can see the rear panel that has been shaped but not yet fitted. It is made up of 3 shaped sections which are then butt welded together so that it looks like a single seamless  panel. All the other cockpit pieces will be shaped and all welded together until the entire body-tub is all one piece of metal. This will then be welded to the frame making the entire tub very strong.

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Below you can see the rear panel from the inside, the top 2″ will be rolled over the top of the tube which once complete will render the top tube invisible to the eye. Naturally this will be done by hand.img_2915

Below you can see the very loosely shaped side panels which will again be rolled over the top tube.img_2904img_2903

At this point Chris offered me a lesson on the English Wheel which was an opportunity that i was not going to turn down. For the exercise Chris chose to show me how he was going to shape the cowl/fairing just in front of the driver. This panel has so many curves going in so many directions that it is ridiculous. He said it was fairly straightforward but I rather suspect he was playing down the skill it requires. He explained that to make this panel there needs to be a section in the middle that must never be touched by the wheeling machine. This is because stretched metal is forced to rise up away from the untouched section and you keep stretching the metal up until you have the shape you want.

This is not the greatest of drawings but you can see the panel we were going to make. You will see that one side of it has a MUCH higher curve than the opposite side and that intense curve needs to slowly diminish as it heads toward the front of the car. But that intense curve is only in part of the panel too so the cowl/fairing is like a hump in the middle of a sweeping curve… and all from a flat piece of aluminum.img_2916

The numbers are the mathematical formula for the work required. For every push or pull of the wheel in the section with a ‘1’ in it, the higher regions require a much higher order of magnitude of effort to achieve the curve. I.e. for every one push in the lower section, the highest section requires 8.. that soon multiplies up to a lot of effort to make a hump in the panel.

220px-englishwheel-with-rollersThis is an ‘English Wheel’

Basically, the operator of the machine passes the sheet metal between the top wheel and the rolling ‘Anvil’ wheel just below it in a push-pull motion. This process slowly stretches the material and causes it to become thinner. As the material stretches, it forms a convex surface over the anvil wheel. This surface is known as “crown”. A high crown surface is very curved, a low crown surface is slightly curved. The radius of the surface, after working, depends on the degree that the metal in the unworked middle of the work piece stretched relative to the worked edges of the piece. This is because the unworked area essentially holds the original shape in place. Simple isn’t it <coughs theatrically>. It made more sense when he showed me.

Chris marked out the no-go area of the panel and showed me the basic technique advising you need little force to push the metal between the wheels but that i needed to apply a slight lift to the panel when wheeling which teaches the metal where it needs to go. ‘And stay out of the no-go area!’. He then left me to it saying i was unlikely to do anything drastic at this stage. Initially I had no control where the wheel went over the metal (so much for keep the wheeled lines next to each other), I had the wheel wandering all over the metal seemingly wherever it wanted to go but slowly i got the hang of it – it transpired you have to guide the metal in the REVERSE direction to where you wanted the wheel to roll. I have to admit after 10 minutes I had tired arms but I could see that i had in fact put a slight curved shape into the panel. I handed the operation back to Chris who was both faster and far more accurate than my feeble attempts. After about 30 minutes, the panel had a vague essence of the basic shape but was clearly heading in the right direction. The estimate for completing that panel is one to one and a half days of wheeling! So its not a quick piece of work. Sir I salute you, i am not sure I would have that kind of patience. On my next visit I am told I will see this panel completed and when you see the final shape we will appreciate how much effort went into making it. After only 30 minutes it is nowhere close!

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Jumping topics, in the meantime the petrol tank is now fully shaped and ready to be welded up then pressure tested. It will incorporate the period petrol cap that originally came from their monster Bentley which is a nice period touch. The artisans have done a sterling job of recreating the shape of the original tank and accommodating my supplied fuel level sender which although modern is designed for speedboat fuel tanks – there are no moving parts other than a float that rises up a pole. So it is unlikely to ever go wrong, I will adjust the fuel gauge to read the output of the sender correctly (a subject for another day)

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Bodywork Update

The Aluminum frame is now fully formed and we are agreed that this is what i was looking for. Every joint will now be fully welded and ‘finished’ so that the skin fits tightly and the various joints will receive  strengthening fillets to make the whole structure even stronger.I am really pleased with the way all the top surface lines flow together and the little curve at the rear is simple but it adds a certain something.

What really surprised me is the weight of the frame – i.e. it hasn’t got much, you can easily lift the entire frame with just one hand and even though most of the joints are only tack welded into place – it is already pretty strong. Once all the fillets are in place, every joint is fully welded and the outer skin is fitted, this will be one strong car body but importantly still very light which can only improve the cars performance.

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In the photos below I think you can now see the shape of the bodywork. You may not notice this but the arm cutout for the passenger is very slightly different to the drivers side. This is because the top of the dashboard on the near side is lower than the off side. More practically, the two sides of the car are actually different in needs –  the driver badly needs elbow room so to accommodate this, the front passenger sits an inch or so lower and slightly behind the driver. The arm cutout has been mildly adjusted to suit but like the off-side is a lovely curve into the instrument panel area.img_2891

In the picture below you can see the finished shape of the back and note how the frame in front of the steering wheel curves up to match the steering wheel and then sweeps down into the drivers arm cutout. img_2892img_2896The chaps at Bespoke Bodywork reluctantly agreed to appear in the blog – I caught them whilst they demonstrated the fit of the petrol tank… A talented team, left to right we have Dan (engineering), Harry (learning the trade) and Chris (owner and chief artisan)img_2894The petrol tank sits in its original position but is no longer protected by any bodywork and you can see how close it is to the rear wheels.  To prevent stones thrown up by the rear wheels penetrating the tank with the obvious consequences, we decided to follow the wisdom of Vintage Bentley’s and fit a stainless steel mesh for protection. It therefore makes sense to factor in some mounting points for me to create said protective mesh at a later date.img_2895

Next week – the bodywork ‘skin’ commences and the English wheel comes into play for the first time on this car… i will be onsite video in hand to watch this ancient art take place and see how the artisans take a flat piece of aluminum and turn it into a rounded shaped panel.

Coach builder plaques

Just thought I would share today’s art and craft. Now that I know I can craft etched brass items and I know I can distress and age brass I thought I would see what happens if I combine all the Techniques. 

Below are further prototypes of the coachbuilders plaque. Leave me a comment as to which one you think looks the most like a 1930’s original…


You will note that none of them are ‘shiny’, after 80 years the brass would have definitely tarnished…