If you’re reading this, chances are there’s a vehicle in your garage still using one of GM’s tried and true, Saginaw-manufactured steering boxes. Power-assisted and manual steering boxes can be found in about every GM vehicle throughout the muscle car era, up until GM started installing rack and pinion steering in its vehicles in the 1980s. Even then, the trusty Saginaw steering box continued to be used in GM cars and trucks into the 2000s. Our S10 was built in 1999, and with over a quarter-century of use and untold miles of abuse, the steering of our little truck was “sloppy” at best. It was time for a steering box rebuild.

The steering assembly on our S10 is pretty simple, but it has over 250,000 miles on it. We pulled the steering box and sent it off to Turn One for a rebuild.

Sloppy steering and leaking seals are common signs that it’s time to rebuild the steering box in your ride. Our S10 exhibited both issues and after a fair amount of research, we contacted the folks at Turn One, Inc. to rebuild the steering box in our little truck. There are plenty of horror stories about parts store “rebuilt steering boxes” that are just an aerosol overhaul of a tired, worn-out steering box. A few cranks on the adjustment stud and a new set of seals will hold the fluid and limit the slop almost until the end of the warranty period. Then, it’s time to replace the box again. These steering boxes are heavy and we wanted to do this right. The original box lasted for over a quarter-million miles, so a properly rebuilt box should last as long as we own the truck.

The Saginaw Steering Gear Division of GM built several varieties of steering boxes for GM cars and trucks. There are also different steering ratios offered as well as steering boxes mounted with either three or four bolts to the frame. Gearboxes made before 1980 use 5/8- and 11/16-inch SAE inverted flare fittings, while steering boxes manufactured after 1980 will have 16mm and 18mm O-ring fittings. This information is important if you plan on scouring the salvage yards for a rebuildable steering box core so you can drive your pride and joy until the rebuilt steering box arrives.

Rebuilding A Steering Box

When it comes to rebuilding steering boxes, it pays to rely on experience. A benefit of using a source such as Turn One is the options available during the rebuild process. Thanks to their years of experience, Turn One can fine-tune your vehicle’s turning by adjusting the valve within the steering box during the rebuild. This allows the effort needed to turn the steering wheel to be better suited to your liking and driving style.

This is where the power-assist magic happens. This is the rack piston and the worm shaft. The valving in the rack piston directs fluid to the power-assist and the recirculating balls interact with the worm shaft to rotate the Pitman shaft.

Components inside the steering box valve determine how much power-assist is provided when turning. Adjusting this valving allows for a lighter or heavier feel at the steering wheel. If you think the steering is too “light” or “floaty,” or are looking for that “old Cadillac feel” when turning, be sure to discuss this during the order process.

Rebuilding the steering box is not rocket science, but it does require skills to know what to look for, and the time and attention to do it correctly. – Mark Kawiecki, Turn One, Inc.

Proper Saginaw Power Steering Box Rebuild

There are several steps that separate a proper steering box rebuild from simply installing some gaskets and seals. Mainly, the steering box needs to be totally disassembled, cleaned, and inspected. There are numerous areas that are prone to wear. Rust can be another issue, especially on the input and Pitman shaft.

The input and Pitman shaft both rely on bearings to allow proper rotation of each shaft without unwanted runout. These will understandably wear over time. Simply replacing the seal for each shaft will stop a fluid leak for a while. But, over time, the excessive runout will exacerbate the wear on the new seal, setting it up for premature failure. Even if the wear is not noticeable to the eye, when machined tolerances stack up, they add up to an issue you’ll feel in the wheel.

The gearing inside the steering box provides a lot of force to turn the front wheels of a vehicle. This gearing is ingeniously done through a set of recirculating balls that ride on the worm shaft. Turn One’s Mark Kawiecki explains this is the most common wear point on steering boxes due to the amount of force each of the balls endures day after day. Removing, measuring, and installing the reciprocating balls can be tedious, a reason some places ignore this important part of a proper rebuild.

Worn recirculating balls is a major contributing factor to excessive lash in the steering. Turn One replaces these worn, recirculating balls with new, properly sized ones on the vast majority of box rebuilds they do. Restoring the proper size balls is one way to ensure the box provides as tight off-center steering as possible.

What Is That Adjustment Screw For?

One of the biggest mistakes that many enthusiasts make when working on their steering boxes is performing uneducated adjustments to the Pitman shaft over-center preload screw on the top of the steering box. While this adjustment is important in setting the proper preload, it is not intended to simply “tighten up” an ailing steering box.

That screw is designed to set the preload of the teeth on the Pitman shaft with the pinion gear. It must be set to a specific torque value that is measured in inch-pounds with a torque wrench as the input shaft is moved through the center of its range of motion. This is because the clearances of the pinion gear teeth to the worm shaft are closest in the middle. This is by design to ensure the tightest steering possible to prevent wandering while driving straight. Over-tightening the preload can cause binding in the steering feel and increase wear on the teeth. Having the proper preload is an important adjustment, but is only one small piece of having the box in good working order. You can’t fix a sloppy steering box by simply adjusting this screw.

Putting The Box To The Test

Even after the box has been rebuilt to like-new condition, Turn One goes a step further and connects every rebuilt steering box to its in-house dynamometer. During this test, fluid is run through the box. This ensures that the seals are working properly, the valve is operating normally and is balanced, and that the box will work as it should once installed on the vehicle.

Once you receive the rebuilt steering box, there are a few things you should do to ensure that your better-than-new box will enjoy a long, happy life. Before hooking up those fluid lines, now would be a great time to swap them out for new ones. We even installed a new power steering pump as part of our rebuild. This ensures that all of the old, filthy power steering fluid doesn’t work its way into your newly rebuilt box. Besides, that old pump was working, but how well? At a minimum, you should flush the existing pump of any old fluid.

Sometimes, the simplest performance upgrade you can do to a vehicle is restoring its systems to be as good as they were when it left the factory. Whether your car or truck has power steering, a manual box, or even a rack and pinion steering, Turn One can rebuild these steering assemblies for peak performance, tailored more to your driving style and preference.

The company also offers rebuild services for a variety of power steering pumps, which allows for similar fine-tuning, and you receive your pump back after a complete refresh. Turn One will inspect each component sent in for rebuilding and advise you if any parts require replacing. Turn One does not stock any previously rebuilt products — what you send to them is the same product you receive back unless there are enough issues to warrant a complete replacement.

As mentioned, we only wanted to do this job once. That is why we also swapped out the entire steering gear with completely new steering linkages including the relay rod, inner and outer tie rods, and idler arm.

If you are truly looking for more performance than the OEM components can supply, Turn One also offers a variety of high-performance power steering pumps and other components tailored specifically for racing and competition. Check out the services and components offered for your application and you’ll quickly see that a questionable, over-the-counter steering box rebuild is far from your only option!