IS A VW PAN REPLICA SPEEDSTER A SPORTS CAR ?
Seems that would be an easy and obvious definition, but is it? Let's look at the history and evolution of sports cars.
With the introduction of the "horseless carriage" automobile back in the early 1900's the fascination with speed carried over from the racing horses, steam locomotives, and ships of the day. But in order to best their competitors enthusiasts had to do things that separated their automobile from the norm. It became quickly apparent that more power and/or lighter weight was an easy first step. Aerodynamics did not come into play until much later as speeds began to increase to the levels where it was a factor surprisingly much later than you would think. So stripping off all nonessential sheet metal, tops, spare tires, bumpers, etc and strapping on a leather cap was common and the early automobile racing and sports car was born.
But those simple beginnings soon changed as that interest showed the manufacturers of the day that not only was there interest in their popular grandiose saloon vehicles there was also interest in speed and handling. That interest spawned the famous factory "sports cars" of the era. The Auburn Boat tail Speedster was a good American example and the Europeans were doing the same thing. As with all evolution it became clear that power and speed was only a small part of the challenge so things began to change rapidly. Better handling required a better understanding of suspension technology. Better braking required the same. The list grew long such as better tires, better cooling, better fuel and oils, better structural materials, and the list goes on.
So by the above definition created by the experience of our early enthusiasts a "Sports Car" was for the thrill of speed and handling, but along with that a host of technology and upgraded systems that were not necessarily required or found on daily cars was needed.
That basic definition has not changed much in the last 100 years. Street type cars used for daily transportation are not designed or expected to act as a sports car. Now there are sports cars available for that purpose and we are all awed by the technology and costs that supports them.
Can one expect to simply remove the body of a street car and replace it with a sleek racing or sports car type body and expect sports car performance? Not likely.
The quintessential example of that effort is the VW based 1957 Speedster replica. Does it become a true Sports Car by that simple alteration? Let's examine the process.
By removing the body of a VW Beetle from its pan the majority of the structural integrity of the vehicle is lost.
In order for a replica Speedster Body to fit over that pan properly the pan must be shortened approximately 13 inches. All of that reduction is accomplished by moving the front axle rearward. That causes the weight bias to be shifted dramatically also rearward because all of the overhanging weight of the Beetle remains in the same place. So by default the replica is now heavier on the rear and lighter on the front. Adding weight with larger engines or adding accessories like AC and multiple carburetion exacerbates the problem.
The engineering term that defines this is "polar moment of inertia" which quantifies the resistance of a structure to rotate about it's center of gravity. Low numbers are good (balanced) High numbers are bad (imbalanced).
Now that you have the replica body sitting on the shortened VW pan it is immediately obvious that it is sitting 4+ inches too high. The suspension must be lowered on the front and rear. That is accomplished by rotating (detuning) the front and rear torsion bars. That does lower the car but it does not lessen the spring weight capacity required by the much heavier Beetle so spring rates are not specified by need but rather by default. More importantly lowering also disturbs the unusual VW factory alignment specifications for the Beetle and getting them back to a "Sports Car" type alignment is problematic. I personally feel it is impossible without extreme suspension alteration i.e. delete the Beetle suspension and replace it with an alternative. A parallel problem is the light front end that is created by this shift of weight reduces the front braking and steering control of the car due to less normal downward force.
So far all of the desirable "Sports Car" features are not economically or practically achievable. They are:
Very low center of gravity
Very low polar moment of inertia (front to rear balance)
lowered ride height
performance suspension alignment focusing on "Zero Bump Steer" in addition to desirable caster, camber, and toe specifications
Here is an example of the results of not being able to achieve these desirable traits https://youtu.be/nbY-u1BeBUQ
6. I think the point is made so I won't get into the other considerations of structural integrity, appropriately sized brakes and suspension components, fuel tank location and protection, seat belt anchorages, and street use legality.
7. Compare an altered Beetle pan used under VW Speedster replicas with a properly designed and engineered chassis used for the same purpose that achieves all of the desirable traits and much more. The engine overhang on the beetle chassis is painfully obvious as is the lack of occupant protection.
7. In summary if it were an acceptable industry practice to neglect the above desirable Sports Car features then all Ferraris, Lamborghinis, Maseratis, Porsche Caymans, among many others would have rear engine locations.....they do not.