MANUAL STEERING SYSTEMS ON OLD CARS, Part I
Steering gears in old cars very rarely fail; at least, that has been my experience in the 40-plus years I have been working on them. The steering linkage, king pins or ball joints wear out, but not the steering gears. It was because of this durable, dependable system, that I decided to research the different systems as they apply to our cars, to see what made them so tough. I decided to cover the three basic types: Saginaw, Gremmer and Ross. There are others. Lincoln had their own, with the 1935-40 K Series, and Packard had their own, with the 1937-38 Super 8s and 37-39 V-12s. But the three I will cover here are the ones most commonly used on American cars of the '30s-'60s. My purpose is to give a general view of each system and provide a chart at the end of the article to show what cars used which system. In future articles, I will go into a more thorough description of each, including adjustment and lubrication procedures.
The basic function of an automobile steering system is to guide the car by the use of the steering wheel, which, linked by gears and levers to make the front wheels turn the car. The bottom end of the steering wheel shaft has a worm and roller gear assembled so that when you turn the steering wheel, its worm gear rotates. As the gear rotates, the roller is moved toward one end of the worm. This carries through the roller shaft to the pitman arm. The lower end of the pitman arm swings toward one side as the steering wheel is turned. The swing of the pitman arm moves the tie rods, connected to the end of the arm. The other ends of the rods are connected to the wheels steering knuckle arm. As the pitman arm moves, it either pushes or pulls the tie rods, causing the wheels to turn one way or another.
Most steering systems use a worm gear on the lower end of the steering wheel shaft. The difference in systems is the piece that meshes with the worm gear, i.e., stud, sector, half nut, plain gear or roller.
THE SAGINAW STEERING SYSTEM
Saginaw was originally founded in Saginaw, Michigan in 1906, and was bought by Buick in 1910, subsequently becoming part of GM. In 1926, a new worm and worm wheel gear system was introduced, and by 1934 became standard in all GM cars.
Although the basic theory stayed the same, GM used ten variations of the Saginaw system, some of which were simply different ways to adjust the mesh.
The Series 500 Saginaw is a circulating ball type. Its operation is a roller with either two or three teeth, mounted on the pitman arm shaft, which engages the worm groove in place of the sector-type teeth. When the steering shaft and worm are rotated, this causes the roller teeth to follow the worm groove, rotating the pitman arm shaft. The worm thrust bearing cones are in an eccentric sleeve that can be rotated within the gear housing to move the worm away or toward the roller, allowing the correct mesh adjustment of the worm groove and roller teeth.
The Saginaw 420/450 is a worm and roller type with eccentric sleeve adjustment of the worm and roller backlash. Its operation is a roller with two or three teeth, and is ball bearing mounted on a pitman arm shaft, engaging the worm groove instead of the conventional sector type teeth. When the steering shaft is rotated, this causes the roller teeth to follow the worm groove and rotate the pitman arm shaft. The worm thrust bearing cones in an eccentric sleeve can be rotated in the gear housing to move the worm to or from the roller, providing the correct mesh adjustment.
The Saginaw 320 is a worm and roller type that has an eccentric adjustment incorporated in the housing to remove worm and roller backlash. Its operation is a roller with two teeth, ball bearing mounted on the pitman arm shaft to engage the worm groove. Turning the steering shaft and worm causes the roller teeth to follow the worm groove, rotating the pitman shaft. The housing is made up of two parts. One part is frame-mounted and supports the pitman shaft, and the other part supports the worm thrust bearings and steering column. To align the two parts, eccentric and pivot-bolts are used. Rotation of the eccentric bolt changes the housing-to-housing position and controls the worm and roller backlash.
Next month, well cover the Saginaw 250, and the Gremmer and Ross steering systems. Understanding the basics of our steering systems will help us identify problems, and following our motors manual's adjustments and maintenance will help assure smooth, trouble-free operation. See you next month. Keep 'em driving!