Report from Barrett-Jackson Auction

[Jim Maxwell]

Here is a brief explanation of the basic manual types of steering. The worm and sector cars are felt by some to have less road feel than the more modern rack and pinion cars. The first 125 Cobras were worm and sector, 75 of those being 260 c.i. engine cars. You can easily tell a "worm" car by the "flat" steering wheel--an instant give-away. The cars should also not have side vents, although many have had vents added over the years. There are also rack and pinion cars with no side vents, however (first 160 cars), so don't use that to determine the steering.
Manual Rack and Pinion Steering
A typical rack and pinion steering gear assembly consists of a pinion shaft and bearing assembly, rack gear, gear housing, two tie rod assemblies, an adjuster assembly, dust boots and boot clamps, and grommet mountings and bolts. When the steering wheel is turned, this manual movement is relayed to the steering shaft and shaft joint, and then to the pinion shaft. Since the pinion teeth mesh with the teeth on the rack gear, the rotary motion is changed to transverse movement of the rack gear. The tie rods and tie rod ends then transmit this movement to the steering knuckles and wheels.


Manual Recirculating Ball Steering
With the manual recirculating ball steering gear, turning forces are transmitted through ball bearings from a "worm gear" on the steering shaft to a sector gear on the pitman arm shaft. A ball nut assembly is filled with ball bearings, which "roll" along grooves between the worm teeth and grooves inside the ball nut. When the steering wheel is turned, the worm gear on the end of the steering shaft rotates, and movement of the recirculating balls causes the ball nut to move up and down along the worm. Movement of the ball nut is carried to the sector gear by teeth on the side of the ball nut. The sector gear then moves with the ball nut to rotate the pitman arm shaft and activate the steering linkage. The balls recirculate from one end of the ball nut to the other through ball return guides.


Manual Worm and Sector Steering
The manual worm and sector steering gear assembly uses a steering shaft with a three-turn worm gear supported and straddled by ball bearing assemblies. The worm meshes with a 14-tooth sector attached to the top end of the pitman arm shaft. In operation, a turn of the steering wheel causes the worm gear to rotate the sector and the pitman arm shaft. This movement is transmitted to the pitman arm and throughout the steering train to the wheel spindles.