General Motors Original Equipment (OE) steering system components offer added peace of mind that comes with knowing the parts have been thoroughly tested and rigorously validated, and are engineered with years of development know-how.

These components – including gears, the intermediate shaft, tie rods and the steering column – help establish the ride and handling for a vehicle, as well as directional control and steering assist for its operator. As a result, hundreds of tests are performed on vehicles’ electronic power steering systems before GM approves them for installation, examining areas such as durability, performance, corrosion, fatigue and temperature cycle. Aftermarket competitors that offer only individual components might not perform testing and validation as a system.

Put to the Test

For example, GM “shakes and bakes” all the electrical components of the system, says Christopher Mielke, a GM engineer for Steering Systems. “That means each individual part is repeatedly heated and cooled to extreme temperatures in order to test all critical electrical connections, while at the same time vibrated violently to expose potential weakness,” he says.

During testing, the steering gear not only undergoes salt-spray testing in a lab, but also at a full-vehicle level using accelerated corrosion exposure with salt spray, extreme heat and extreme humidity in a test booth. It goes through real-world corrosion tests by being exposed to actual road salt and road-salt splash elements for months at a time at GM’s Milford (Mich.) Proving Ground. In addition, the components endure impact loading to test their strength and verify performance during normal everyday driving as well as those more unexpected events, like driving through a pothole.

“We’ll hook hydraulic actuators right to where the tie rods usually attach, and we’ll beat the thing up pretty bad,” Mielke said, adding that the tests are meant to simulate what the vehicle would be like over two lifetimes of rough ownership.

It’s important to remember that GM OE vehicle steering systems include complicated mechanical, electrical and software components. The steering gear in particular is running its own diagnostic checks more than 1,000 times per second to make sure it’s functioning properly, alongside the thousands of similar checks the vehicle itself is doing. “The symphony of components must work in unison to provide ride, handling and safety performance that GM customers expect,” Mielke says.


Safety First

Replacing steering components with aftermarket parts could affect the vehicle’s original crash test rating. The differences between the GM OE and aftermarket parts may be subtle (such as a modified dimension) or dramatic (such as when components within the system are eliminated altogether).

Some design features on GM OE parts may look extraneous – like a random bump or groove, for example – but likely play key roles in the event of a crash.

Such features on the rack and pinion are designed, for example, so that when another part of the vehicle is collapsing during a crash, they will deflect energy off the steering gear. “This could help prevent a fuel line from being cut, for example,” Mielke says. “They may not appear to do anything, but it’s a little nuance that aftermarket companies could overlook in their design.

“No company or parts brand knows your GM vehicle better than the company who designed and manufactured it from the ground up,” he adds. “That is especially true when it comes to a crucial safety component such as a steering system.”