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.
After receiving a steering-rack...
After receiving a steering-rack assembly, Turn One begins the refurbishment by completely disassembling it, starting with the removal of the tie-rod boots. A couple of clamps hold them in place, but the job gets messy quickly if the rack’s seals were breached and fluid leaked into the boots.
"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.
With the boots out, the tie...
With the boots out, the tie rods themselves are removed next. It’s a relatively simple process to loosen them, but it requires a healthy dose of leverage. With one end of the assembly held in a vice, a long lever is used over a wrench to break free the fastener.
After the tie rods are removed,...
After the tie rods are removed, the steering-rack shaft itself is exposed. It protrudes from both sides of the rack housing, and careful measurements must be taken to ensure it is centered in the housing. The center point determines the position of the “whistle notch.”
The whistle notch is seen...
The whistle notch is seen here as the divot on the shaft (left side of photo). Its position, as determined and described in the previous caption, must be matched exactly during reassembly or the car’s steering wheel won’t be straight.