1966 NASCAR International Rule Book Specifications NASCAR Grand National Championship Circuit Section 20-27 -- Suspensions

a. Heavy duty springs may be used if similar to original equipment.

b. Sway bars may be reinforced. Additional sway bars permitted.

c. Front end suspensions must be reinforced for safety. Heavy duty spindles and bearings compulsory.

d. Camber: 4 ° maximum.

e. Wheelbase: AMA specs apply. Standard plus or minus 1/2 inch. Left and right must agree. No intentional altering of wheelbase. Minimum wheelbase (See Rule 1).

f. Tread, front and rear: AMA specs apply plus or minus not over one inch tolerance on either side to allow for reinforcement of wheels and hubs, measured at center of tire, zero toe-in at spindle height, standard not offset.

g. Mechanical device will be permitted in order for driver to shift weight while in motion, provided it doesn't alter minimum ground clearance. No hydraulic weight shifting devices permitted at any time.

h. Minimum of ground clearance of 6 1/2 inches on the left side, measured from the lowest part of frame or body, and not more than 2 inches higher on the right side, measured from the lowest part of frame or body. Oil pan minimum ground clearance 5 inches; exhaust pipe minimum ground clearance 4 inches. (Use of any special device to obtain minimum ground clearance will subject the car to disqualification because such device may become dislodged while car is in motion, thereby lowering the car below the approved ground clearance.)