This project, as you can see has been through a bunch of changes. But, I have finally settled on what I am doing. I decided not to use the Miata tub and create a body to fit it. The Miata's short wheelbase, center seating position, high cowl, forward mounted and high mounted engine just didn't allow me to get the look that I wanted. I like the the rear seating position, lower cowl, and long bonnet look of the old sports racers.
I built a dedicated space frame for the Miata suspension parts and drive train to bolt into. I set the wheelbase at 95 inches. Then moved the engine rearward by 8.2 inches. This gets the engine lower as well. I shortened the torque arm by 8.2 inches as well. The ride height is 4.5 inches and the oil pan is flush with the bottom of the frame. The finished frame with roll bar weighs 229lbs. The roller weighs 1252lbs. Not a light weight but I think it's pretty good.
I did not use the Miata pedals and MCs. I am using floor mounted ones. This allowed me to lower the cowl height significantly. The 95 inch wheelbase lets me sit much lower. I am shooting for 54% rear weight with me in the car. I am using the collapsible portion of the Miata steering shaft. I turned it down so that it fits into a standard 3/4 inch ujoint. The balance of the steering is race car style with a quick release hub.
The Miata has very high shock towers. I didn't want to use stock shocks as the tower height would impede on the lower bonnet look that I am going for. I found that small body racing coilover shocks and springs fit perfectly. In the pictures my motor mounts and shock towers do not have the final bracing. That's about all that is left to do though.
I am making a couple of bodies to fit the frame. More to follow. I am skinning the sides with aluminum then making a front and rear clip out of fiberglass for a 7 inspired look. I purchased a 1958 Devin SS inspired replica body that I am using to create the 50's sports racer. I am widening, lengthening, and changing it to my taste. Because my frame has a stressed backbone I can have function doors. The 7 inspired body will not have doors. The Sports racer body will have functioning half doors.
The windshield is from a Porsche 356 Speedster. I think that it has the correct look, is legal, and is readily available at a reasonable price. Plus it is available in 3 heights, Speedster, Convertible, and Coupe. Using it will allow me to develop different versions.
I am totally into getting this done now. Having fun.