a STOCK 1965-66 K-code/GT Coil spring is 600 pound increased rate--does not lower car 1 inch
That would be a C5ZZ-5310-A spring. (1491 load rate, 0.60" wire diameter, 8 coils total in free length and 4.45" is the mean diameter)
From the math.......11,250,000 x (.6 x .6 x .6 x .6) / 7 x 7 active turns x (4.45 x 4.45 x 4.45) = 337 Lbs/in
The GT/Special Handling spring was not even close to a 600 pound spring.
Our .67 wire diameter spring for our kits was marketed at 540 pound and by the equation above is right around over 500.
Shelby used the stock springs; in conjunction with the Arning drop, that's how the cars ended up about 1/2" lower.
ex-Global West GM
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