Street rod steering has come a long way. The current traditional street rod movement has precipitated a move to more traditional steering gear. From early Ford, frame-mounted steering boxes to the ever popular through-the-cowl steering-what was old is new again.
Prior to World War II, and just after World War I, the '37 Ford Gemmer parallel drag link, push/pull, steering box was the norm for steering box swaps. Gemmer Manufacturing of Detroit manufactured the steering boxes for Ford, thus the term Gemmer. Pre-'37 Ford Gemmer steering boxes featured a fixed sector gear, resulting in high resistance and fairly rapid wear. The later Gemmer boxes had a recirculating sector gear, which allowed easier steering, less wear, and a faster steering ratio, and most importantly, they fit neatly onto a Model A or Deuce frame. The preferred Gemmer box was available in Ford, and some other passenger cars through 1948, and in Ford trucks through 1956. This was the hot setup for those postwar hot rodders and dry lakes racers.
Mike Bishop and Vern Tardel discuss all of the ins and outs of installing the Gemmer steering box in their book A-V8 How to Build a Traditional Ford Hot Rod. Tardel also authored a Let Me Help You manual that gives all the information and tricks needed to rebuild and install the early Ford steering box. The manual is available from Vern Tardel Enterprises or Speedway Motors.
The modern era of steering came in the early '60s with the introduction of the recirculating ball and nut gear Corvair steering box. The recirculating ball and nut steering mechanism contains a worm gear inside of the steering box with a threaded hole through it. The worm gear has gear teeth cut into the outside to engage the sector shaft (also called a sector gear), which moves the pitman arm. The rotation of the steering shaft rotates the worm gear inside the steering box and instead of twisting further into the block, the worm gear is fixed so that when it rotates, it moves the sector gear, which transmits the motion through the gear to the Pitman arm.
The worm gear is similar in design to a ball screw; the threads are filled with ball bearings that recirculate through the worm gear as it turns. The balls serve to reduce friction and wear in the gear and reduce slop. Until the advent of rack-and-pinion steering, this was the prevalent steering mechanism in passenger cars and trucks.
Early Ford Gemmer steering...
Early Ford Gemmer steering boxes are still available. We located this one at a local swap meet.
Available in both cast iron and aluminum, the Corvair box, especially a polished aluminum model, was popular with the T-bucket brigade. Usually mounted on top of the frame, the input shaft must be reversed in the housing for parallel-drag link steering.
In order to reverse the Corvair box you must first disassemble the box. After disassembly, drill a 3/16 pilot hole in the center of the pot metal worm screw adjusting nut; follow that with a 7/8-inch hole. Tap a new shaft lip seal in the newly drilled hole. Remove the shaft seal and install a 7/8-inch freeze plug in the hole where the steering shaft formally exited. Both ends of the unit already have identical bearing races so that isn't an issue. Then, reassemble the box with the steering shaft coming out of the hole you drilled in the adjusting nut. California Custom Roadsters (CCR) has a kit containing the required bearings, seals, and instructions for reversing a Corvair box.
If that is too much work or you don't have a Corvair box to modify, CCR, Flaming River, and Speedway Motors, all offer a steel, reversed Corvair-style steering box. CCR also offers a remanufactured, polished aluminum Corvair box.
This tapered shim is available...
This tapered shim is available from Speedway Motors, or Vern Tardel Enterprises. The shim allows the F-100 Ford pickup truck Gemmer steering box to be used in tapered passenger car frames without modification to the steering box flange.
In the mid-'60s Ford introduced the recirculating ball and nut gear in the first Mustangs. It was truly a reliable manual steering box and it was designed to work with the 2,500- to 2,700-pound Ford Mustangs. A much better match for a street rod than the Corvair, and as an added bonus the Mustang box did not need to be reversed. The Mustang box was mounted to a plate on the frame, near the firewall and operated in a push pull fashion, with the Pitman arm located at the 12 o'clock position. Speedway Motors, and others, offer a weld-on plate to mount the Mustang box. Some do not consider the Mustang box traditional, but it has been around for over 40 years, so where does tradition begin?
In 1971, GM introduced the Chevrolet Vega. The Vega steering box was a recirculating ball and nut design, similar to the Mustang. Street rodders soon gravitated to the Vega as the steering box of choice, and since that time the Vega steering box has gone on to become the mainstay for street rod steering. Like the Mustang box, the Vega box was mounted to a plate on the frame near the firewall and the Pitman arm was located at the 12 o'clock position when used in a push/pull, drag link, design.
Soon rodders discovered that the Vega box could be used in a cross steer mode in a street rod. While not everyone agreed, the cross steer system was considered superior to the parallel drag link system in that it reduced bumpsteer. Soon street rod parts manufacturers were offering bracket kits to mount the Vega box in almost any frame in a cross-steer style.
The Saginaw 525 manual steering box is a larger version of the popular Vega box and is more suited for cars over 3,000 pounds, like fat-fendered hot rods. The Saginaw 525 has the standard three-bolt mounting pattern found on the Vega and is interchangeable in the mounting, however, the Saginaw 525 output shaft splines are larger than the Vega.
For tradition you can't beat...
For tradition you can't beat an early Ford steering box mounted to '32 'rails. Check out the neat tie-rod end .protector.
Mustang, Vega, and Saginaw 525 steering boxes are available from Borgeson, Flaming River, Speedway Motors, and others. A high tech, billet aluminum version of the Vega-style box is available from Borgeson. The newly manufactured and remanufactured steering boxes available today are often better than the original parts, in that they have larger bearings and utilize modern, close tolerance, machining techniques. Mounting bracket kits are also available from these and other manufacturers.
Although not considered traditional, the Mustang II independent front suspension has a large presence in the world of street rods, both in its stock version and the numerous aftermarket designs based on the Mustang II. The obvious steering choice for the Mustang II suspension was the Mustang II rack-and-pinion steering setup. The popularity of the Mustang II front suspension conversion in street rods has led to a number of aftermarket rack-and-pinion steering boxes for the Mustang II.
This is the steel version...
This is the steel version of the reversed Corvair Steering box available from Flaming River and Speedway Motors. The input shaft now enters the adjusting nut. The aluminum version is scarce, but California Custom Roadsters manages to keep some in stock.
One of the latest steering boxes for a street rod with a transverse leaf spring, solid axle, front suspension, and a cross steer setup is the Unisteer Performance rack-and-pinion steering box. A direct replacement for a Vega-style steering box in a cross steer system, the Unisteer rack-and-pinion steering box gives you the tightness and feel of the road offered by a rack-and-pinion system and the looks of the traditional front suspension.
With the traditional movement in street rods, what was old is new again. We are seeing more frame-mounted early Ford and F-100 Gemmer steering boxes, as well as Mustang, and reversed Corvair and Vega boxes. Obviously parallel drag link, push/pull steering is far more traditional than the cross steer counter part.