Vintage Ford truck owners are familiar with the Gemmer worm-and-roller steering gear. The '37-52 models use a two-tooth roller, and '53-60 F-Series trucks use a three-tooth roller, which adds stamina and provides longer service life. Gemmer worm-and-roller gears have several wear points: the worm teeth, roller teeth, sector shaft bushings, and the upper and lower worm bearings. Due to the popularity of classic Ford trucks, replacement worms, roller sets and other service parts are available.

Saginaw, a division of General Motors, pioneered several steering gear designs. Prior to 1940, Saginaw engineering was similar to Gemmer designs. A worm-and-sector gear was popular on cars and light trucks through 1940. The sector teeth are integral with the sector shaft and do not rotate. Eventually, the worm-and-sector gear teeth develop wear. Minor adjustment is possible with these gears, but significant play indicates the need for a rebuild. Saginaw remedied the friction and wear issue in the 1941-up truck gears.

In 1940, Saginaw pioneered a new steering gear mechanism. Called a recirculating ball-and-nut design, the first application was Cadillac's '40 Model 72. In 1941, all Cadillac models, Buicks, and G.M. trucks acquired this gear type. By the mid-'50s, every G.M. passenger car and truck-whether manual or power steering equipped-came with patented recirculating ball-and-nut steering.

Recognizing the shortcomings and wear factors of a worm-and-sector or roller gear, Saginaw designed a ball nut rack to carry the load. The straight worm shaft has a groove machined into its surface. This precision groove is the inner half of a ball bearing race. Inside the ball nut rack, another machined groove serves as the outer ball race. A set of ball bearings, aided by guide tubes, roll continuously around the shaft and ball nut.

The ball bearing fit is precise. As the steering wheel rotates the worm shaft, the ball nut rack glides smoothly up and down the shaft. Teeth on the ball rack engage teeth on the inner end of the sector shaft. Although the sector teeth do not rotate, the ball nut load distributes evenly over the set of ball bearings. The result is smoother, easier steering than a sliding friction or even roller-type gear.

The Saginaw recirculating ball-and-nut steering gear is the best design to date. Foreign and domestic vehicle manufacturers have adopted its features, and Saginaw supplies gears worldwide. Uncomplicated and exceptionally durable, the Saginaw recirculating ball-and-nut gear has been a popular retrofit for street rods, off-road 4x4s, drag cars, and vintage trucks.

Service And Adjustments
Routine service on any manual steering gear is minimal. Factory manuals call for gear lube checks at each routine service interval. Gear lube can seep, creating the need to top off. Typically, the inspection or fill plug is at the top of the gear housing. Carefully clean the fill plug area before removing the plug.

Lube should be visible with the plug removed and the truck parked level. Typically, the fill point is the base of the plug threads in the housing. Traditionally, the lube was 80- or 90-weight gear lubricant. Some manufacturers allow a mix of cup grease and gear lube on higher mileage gearboxes. (See the shop manual for recommendations.)

Beware of exhaust headers or a large conversion engine that pours heat into the steering gearbox. Seals and gaskets become brittle, and gear lubricant can stiffen or even burn away. Big-block V-8 installations can present these kinds of problems. For whatever reason, there are no drain plugs on a manual steering gear case. When a gear needs rebuilding, contaminated or scorched oil is often a factor.

Adjustments described in the shop manual can be performed with an accurate spring scale or a torque wrench. Note whether the adjustment calls for disconnecting the steering linkage. Be clear about the center position of the steering gear.