Generally speaking, the rack-and-pinion steering systems of C4 Corvettes are dependable performers, and most enthusiasts don't give them a second thought unless they go bad. For the average street car, that doesn't happen, but if your C4 sees a lot of duty in track-day events or is a more dedicated race car, there are some vulnerabilities. For one thing, the power-steering fluid can overheat and damage—or kill—the pump. The rack-and-pinion unit is susceptible to damage from leaking seals and torn boots, conditions brought on by dirt and debris. Left unchecked, these leaks allow the pump to run out of fluid, possibly burning it up and damaging the rack.
Taking care of the power-steering pump is a pretty easy fix—it's simply replaced with a new one. There's no such remedy for the rack-and-pinion unit, however, because it's no longer manufactured. Options, then, are limited to scouring Craigslist and salvage yards for a used part or having the original unit rebuilt. Only a few companies around the country perform the procedure, and we recently stopped by Saginaw, Michigan's Turn One to see how it was done.
It's no coincidence that Turn One is located in Saginaw, because founder Jeff Roethlisberger spent 14 years at the well-known Saginaw Steering plant as a ride-and-handling engineer, specializing in steering development. His shop is located only about 4 miles down the road from the factory, which has undergone a number of ownership changes in recent years (see sidebar). He started the company in 1997, specializing in motorsports steering systems.
Rebuilding the C4 Corvette racks was a part of the business that was born out of necessity, because as we mentioned earlier, new racks are no longer available.
"Fortunately, most of the rack-and-pinions we receive are suitable for rebuilding," says Roethlisberger. "The only thing that keeps us from rebuilding one is if the rack itself is severely damaged or bent."
After receiving the rack-and-pinion unit, typically with the inner tie rods still attached, Turn One completely disassembles it. The components are cleaned and inspected, and the seals replaced. New boots are installed, if necessary, and the entire system is carefully reassembled. As is often the case with such projects, the process is pretty straightforward, but not exactly simple. For example, extreme care must be taken to line up the pinion precisely on the rack during reassembly, to ensure the steering wheel will be straight in the car. Turn One even mounts the rebuilt rack-and-pinion on a specialized dynamometer to check its performance.
Considering the fact that new C4 rack-and-pinion units are no longer available, and the rebuilding process is so specialized, we were pleasantly surprised by Turn One's approximate $200 charge for the service. With the costs of other chassis- and suspension-related components easily costing two or three times that, a fresh rack-and-pinion setup seems well worth the money. A turnaround time of about two weeks is standard, with the customer supplying the core for rebuilding. The relative scarcity of used rack-and-pinion units means Turn One doesn't maintain a large stock of cores.
We followed along as Turn One's Bill Meschke performed a standard rebuild. For the sake of our photos, he focused on a unit that had already been cleaned up, which provided better views of the disassembly process. The accompanying shots and captions depict the significant steps in the procedure. If your C4 isn't carving the turns like it used to, a rack-and-pinion rebuild may be just the thing to steer it straight again.
Saginaw Steering: A History of Twists and Turns
The name Saginaw is synonymous with steering systems in classic GM vehicles. The facility—yes, located in Saginaw, Michigan—was founded more than 100 years ago and has undergone a number of name and management changes over the years, but it still produces steering components. It has also produced axle systems and adjustable steering columns.
The original works was founded in 1906 by three men with last the last names Jackson, Church, and Wilcox; they called the company Jacox. Buick bought the Jacox facility in 1909. It was separated from Buick in 1917 and renamed the Jackson, Church, and Wilcox Division, becoming GM's first parts-manufacturing arm. The name was changed to Saginaw Product Company in 1919 and to Saginaw Steering Gear Division in 1928. The brand name of the products was changed from Jacox to Saginaw in 1930. In 1985, the division's name was shortened to Saginaw Division.
During the early 1990s, the division was folded into GM's Automotive Components Group, which in 1995 became Delphi Automotive Group when it was spun off from General Motors. A decade later Delphi entered bankruptcy, and by 2008, it looked like the steering business was to be sold to a private equity firm; however, the deal fell apart. GM stepped in and got back into the steering business, renaming it Nexteer, but it didn't stay in for long. In the spring of 2010, GM sold Nexteer to an entity backed by the Chinese government.
A More Efficient Pump
One of the steering-system afflictions on C4, C5, and C6 Corvettes is power-steering fluid that overheats, which damages the pump. That can happen in severe conditions, such as racing. Turn One offers replacement pumps for these cars that require less engine power to operate. That reduces the load on the pumps, which helps keep the fluid from boiling. The pumps are simple replacements for their respective steering systems, and for the C4 enthusiast sending in his race-damaged rack-and-pinion for a rebuild, partnering it with one of the new, more efficient pumps makes a lot of sense.