The Great Steering Box Upgrade

Installation Tips And Tricks
Lee builds steering boxes for many major race organizations as well as street cars. He recommends an external reservoir for the power steering pump. Lee's reservoirs use a sealed cap that maintains 10 psi of residual pressure to improve steering pump efficiency. A large reservoir is not necessary. All the GM sheetmetal reservoirs that are integral to the pump also work very well. All plastic GM power steering reservoir caps over the last 30 years have incorporated check valves to create some residual pressure.

Installation Tips And Tricks Lee builds steering boxes for many major race organizations

While a late-model B-car or Monte power steering box swap appears simple, there are a couple of small parts you will need to complete the conversion. Steering boxes for the early '64 to '75 cars used a 13/16-inch-diameter input shaft with 36 splines. After 1976, all GM power steering boxes were changed to a smaller 3/4-inch input shaft with 30 splines. The newer, fast ratio boxes all have the 3/4-inch input shaft with 30 splines. This requires a steering coupler (also called a rag joint) that will fit on the new box input shaft and also bolt up to the older steering columns. Luckily, the '77 to '82 C/K and the two-wheel-drive '83 to '86 Chevy and GMC trucks, as well as the '77 to '78 Camaro, Firebird, and Nova also used this style coupler. We've listed both the original GM steering coupler and aftermarket part numbers that you can use to make this connection.

In the '80 model year, GM also changed from its original 45-degree inverted flare 5/8x18 UF and 11/16x18 UNS female fitting sizes to a metric O-ring (often called Saginaw fittings) measuring 16x1.5 mm and 18x1.5 mm. Coincidentally, the thread pitch of these metric fittings is almost identical to the original fittings, which led Lee to develop aluminum press-in inserts that convert the newer O-ring-style sealing back to inverted flare fittings. Because the thread pitch for both fittings is almost identical, these inserts allow you to use your original inverted flare hoses and fittings.

Included in Jim Shea's original outline is a listing of '92 through '98 Jeep Grand Cherokee steering boxes, all with 12.7:1 gear ratios and 20- to 26-in-lb efforts and the attractive 87-degree travel figures. We did not include these references in this story, but the above Internet references will get you there in a hurry.

The arrows point to the section of the torsion bar that creates the resistance to movement in the input shaft and establishes the box's feel. A larger torsion bar causes more resistance before hydraulic power assist becomes available.

The arrows point to the section of the torsion bar that creates the resistance to movement

Internal Box Modifications
We spent a day at Lee Manufacturing, where owner Tom Lee showed us a few internal components that make up a typical Saginaw power steering box. He doesn't recommend rebuilding your own box. Rebuilding a Saginaw power steering box requires specialty tools and experience, and a poorly assembled box could lock up, which is something you should clearly strive to avoid. Cruising through the junkyard for a suitable box for our '64 Olds, we chose a used '88 F-body WS box that we took to Lee to rebuild. Lee takes the time to carefully blueprint each box, replace any worn or damaged parts, and upgrade the components to fit your requirements. In the case of our third-generation Camaro box, he changed the internal stops in the box to lengthen the pitman arm arc required to give a GM A-body car its proper turning radius.

If you choose to have Lee rebuild a late-model box, there are several options. For example, Lee can easily change the torsion bar in a large-car (B-body) box to increase the effort, but that requires completely disassembling the box. Lee does not have a set price for rebuilds, since each one is a little bit different, but he did give us a range of around $225 to $250 if he starts with a good, rebuildable box.

Variable- Ratio Boxes
Here is where personal preference may come into play. Lee feels the best steering box is the one that is the most consistent, which is why he prefers a fixed-ratio box for performance driving applications. Variable-ratio boxes feature a slow ratio from center that becomes quicker as the steering wheel is turned away from center. A typical variable-ratio box will feature an on-center ratio of 16:1 that changes to 13:1 toward the end of the travel. Variable-ratio boxes generally don't offer faster ratios than fixed-ratio boxes.

By Douglas Glad

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