When did NASCAR make the switch from “stock” (right off the lot) cars to the body-shell-on-a-tube-frame cars they use now?
They’ve always been beefed up. I think it was about the 80’s. I know in the 70’s they still were somewhat sheetmetal and all. Dang. Mid 80’s is my best guess.
It was a gradual change starting in the early 80s. Every year they would make a few more rules to ‘even out the playing field’ and slowly got to where they are today, and they haven’t stopped yet.
As Robert Duvall says in Days of Thunder, “There’s nothing stock about a stock car.”
Or something like that.
I have heard that the cars must be the same shape as a “stock” car. The officials check the cars with templates of the actual cars. Other than that, I don’t think there are any other similarities. I don’t think the engines are made by the car manufacturers either.
The templates aren’t of the actual street car. They’re of the accepted racecar shape, and your car has to be within specs.
The engines are “stock” blocks–i.e. the Ford teams use an engine block that was made by Ford.
As for the change to tube-frames? I’d say the early-mid '60s. They just looked like normal cars until the mid-80s. The 1970 Roadrunner SuperBird was actually avalable in street form with the same interior as a standard Roadrunner, but the racers were tube-framed and full-caged just like the current cars. (I couldn’t find the pic of Richard Petty’s SuperBird with the sheetmetal off showing the frame)
BTW, the street/production SuperBirds were regualar RRs with the wing and nosecone added.
[trivia] More than half of all street Superbirds were wrecked when they rolled off the assembly line, becuase of the ridiculously long (18") nosecone. As each car rooled off the line, it rear-ended the one ahead of it. [/trivia]