Since the age of 11 I‘ve dreamed of building a car. Well, I am now attempting to rebuild a 2 CV, a car I have always found fascinating because of its minimalist design and intelligent features.
But suppose I had a billion dollars and lots of time to build exactly what I want, what I really, really want. Would it be an exotic super car fabricated out of unobtanium with 700 hp capable of 300 kmh? Nope, it would be a simple light, efficient, practical car – very much a modern day 2 CV. It would have many of the features designed into the original 2CV but with improvements to reduce its shortcomings such as rust and noise.
I thought about updating the original 2CV spec to “able to carry a two-four up Carling avenue in early spring without breaking any” but that really doesn’t quite evoke the pleasant pastoral image of carrying a basket of eggs across a ploughed field.
I’d start with a platform chassis like that of the deuche because of its high strength to weight. However, I would make it out of corrosion resistant materials to avoid 2CV vanishing frame syndrome. Unlike the 2CV, I would use some of the space between the upper and lower skins for things like the battery and the fuel tank. The platform would be much wider to form the entire floor of the passenger compartment to help with side impacts.
Just like the 2CV, the car would have trailing rear suspension arms and leading link front arms attached close together to reduce the amount of material required in the platform and therefore keep the weight down.
I would also use the horizontal spring and damper arrangement in the 2 CV but with a few changes. First, the front leading link suspension would have two parallel arms in a configuration that prevents a change in caster as the suspension compresses over a bump. That should take care of the heavy steering that can sometimes occur when braking in a sharp turn. It would also provide an opportunity to move the steering rack into the space between the upper and lower arms where it would be much easier to service. Second, I would select progressive gas dampers. Third, I’d add a front sway bar like the one in the AMI 6 to control lean in the corners and keep the tire patches a little flatter on the road.
Speaking of tires and tire patches, there would be no wide low-profile tires on the car. They add a harsh ride, are hard to keep balanced, expensive to replace, and tend to skitter on snow and ice instead of cutting through. Give me tall skinnies any day. I’d rather keep the center of gravity low and the weight of the car down to maintain handling than adding wider rubber and rims.
I would also keep the flat twin because of its low weight and low vibration, but again with changes. To extend valve and seat life with the lean mixtures that go along with low HCO emissions, and to keep engine noise down. I would reluctantly opt for water cooling. To avoid a drive belt for the water pump, I’d screw it directly to the front of the crankshaft.
To further quell engine noise, I’d dump the pushrods and opt for overhead cams and finger-operated valves with hydraulic fulcrums. I’d use a lightweight belt to drive the cams provided the engine could be built as a non-interference engine. Failing the ability to do the non-interference thing, I’d drive the cams with a chain. Direct injection would allow a higher compression ratio. Then by increasing engine size to about 800 cc it should be possible to up the power but maintain fuel economy. Although I worry about adding the complexity of direct injection, I only have to look at a carb to realize that adding direct injection may actually not add any more complexity at all. Naturally, a slightly offset crank and lighter pistons would be used to keep engine friction at bay. As for 4 valves, they should not be necessary to allow the engine to breath. The deuche’s 602 engine can happily wind to 7k with only two of them, and all that with very little valve overlap.
Instead of an alternator and the lossy drive belt, I would install rare-earth magnets around the periphery of the flywheel which would pass by coils installed in the bell-housing to generate electricity. With a bit of savvy it might be possible to use the coils to start the engine, like the dyna-starters of the past and therefore get rid of the starter too. A distributor-less lost-spark electronic ignition and plasma plugs would complete the picture. Turbocharging would be unwelcome because of the complexity and cost.
Now for utter heresy! Because the engine would be equipped with direct injection, the long intake manifold with the carb perched on top of it would be superfluous making the engine much thinner. By rotating the intake ports to the front of the cylinder heads and the exhaust ports to the rear the engine would be thinner still. This would allow a relocation of the engine to the rear of the car inside the platform and make the car rear-wheel drive. Moving the engine to the rear means a very much shorter exhaust with less opportunity to radiate noise and less weight. Unlike the VW and Porsche, I’d keep as much weight ahead of the rear axle as possible to reduce the bugbear of trailing throttle oversteer.
The heater core would be at the rear of the car along with the heater blower to avoid long heavy and possibly leaky heater hoses full of water. I have a long memory of how long it took to get heat to the windshield of the VW. If the ducts were smooth and made of a low-specific heat plastic instead of steel, airflow would be good and it would not be necessary to heat up all that metal before the heat arrived. The Renault Dauphine used a similar strategy with remarkable success. That little car had a great heater that worked well even in the frigid city of Saskatoon.
Access to the engine would be through an insulated hatch in the rear of the platform. Undoing quick disconnects along with removal of the bumper would allow you to roll the engine, transmission, and all of their ancillaries out the back of the car for heavy-duty maintenance.
The spare tire would move to the front of the car and would be used to provide some impact resistance. The tire would be placed in such a way that it would slide under the car in a collision.
The seats would be split benches on 4-inch legs attached at the edges of the platform. This would allow you to slide boards under the seats the full length of the car. However, I would put a guard plate ahead of the driver’s seat so boards would not slide under the pedals. For big loads, the rear seat could be removed entirely by unscrewing 4 big fasteners that attach it to the platform
The roll-back roof and big vents would be a must to avoid the need for air conditioning. However, I would design the vents to deflect and drain water away and prevent passengers getting wet in a rainstorm like they do in the deuche. I’d also add a second roll roof below the first. This one would be a 60% screen to allow circulation without having the sun burn a hole in the top of your head.
Rear brakes would be inboard and the front would be a fully shielded but vented design as found on aircraft to keep guck and water out of the brakes and prolong brake life.
The poor old deuche was actually surprisingly good in a front impact because of the strong passenger platform and door frame hoops, but not so good in side impacts. This would have to be corrected with reinforced doors.
Another heresy – no frontal air bags. As an ex-firefighter I can affirm that a direct front collision is rare. Most fatal and injurious collisions occur from 15 to 95 degrees off the long axis of the car. Second, occupants always hit the inside of the car more than once, by which time the air bags are on the way to deflation. The biggest problem is associated with the 3-point harness. In a collision, the driver’s unrestrained right shoulder lets his body rotate so his right temple whacks the windshield. I can still recall the large number of windshields with a big bump at the center where the head hit. So, 4-point harnesses for this car. God, Mr and Mrs Uckumslutch would hate this one! The next danger area is where the side of the head hits the b-pillar or the side window. I don’t know of anything else except the use of side air-bag to help with this problem.
Now, about the windows. No expensive window crank mechanisms to interfere with the reinforcements of the doors and add complexity. The windows would tip up like those in the 2CV (but with a better clip to prevent bashed elbows) or, God help us, sliding windows a la Mini.
Because the car has a platform, it would no longer be necessary to have high door sills. This means that the entire floor could be flat and you could therefore wash slush and crud out of the car with a hose, especially if the floor mats were dimpled rubber instead of carpet.
The gearbox would have an extra cog in it, but the shifter would still stick out of the dash near the steering wheel, where it is easy to hand, and yes it is possible to do this even with a rear engine without a complex and spongy linkage. Maybe a centrifugal clutch like that once offered in the 2cv would make life bearable for creeping through traffic. I think it may also be possible to incorporate a motorcycle-style constant-mesh gearbox with 2 clutches for those who absolutely insist on automatic transmission.
A feature I absolutely insist on is the addition of heating ducts to the side windows, front and back, and to the rear window. No expensive electric heater elements to rupture. I’d also add small ducts to each side mirror to keep them clear on frosty days. While we are on the subject of winter, the washer bottle needs to be readily accessible, heated, and able to contain more than one gallon of fluid.
When the deuche was designed it was so slow that aerodynamics could be ignored. Not so it’s modern replacement. A Mazda 5 shape and a smooth underbody provided by that all-important platform chassis would keep drag in check. Naturally, flush headlights and hide-away wipers would be included in the design to keep drag and wind noise down to a minimum. The front windshield would have a deep curve to stop airflow detaching at the sides of the car and inducing turbulence and yet more wind noise.
To keep winter dirt off the rear window, I would add a deflector to the rear of the car that would direct air down across the rear window to keep it clean. The alternative would be an expensive wiper. To keep drag low I would allow it to stow out of the way on dry days.