Weak Springs Cause Power Steering Problems

Rob Spiegel

August 15, 2011

3 Min Read
Weak Springs Cause Power Steering Problems

My girlfriend's daughter purchased a 2005 Chevy Cobalt with 45,000 miles in 2009, per our recommendation, after we expended a considerable amount of time comparing models and reviews from all manufacturers. Three months after she bought the car, the power steering stopped working, intermittently. This got progressively worse. It's very dangerous when you are trying to make a corner and the power steering goes out. All of a sudden, you start sliding into the oncoming lane.

I went online and found literally thousands of postings from people who experienced the same problem. This issue generally cropped up anywhere from 30,000 to 60,000 miles. I contacted Chevrolet service in Detroit and was advised that this was the first time it had heard of the problem. I told the agent there were hundreds of cases where people stated they had also contacted the factory, and hundreds more who contacted their local car dealership. All received the same reply.

These models use a DC motor and gearbox arrangement located just under the steering wheel panel to provide the power assistance. They are actuated electrically, not hydraulically, as with other models that have power steering pumps and reservoirs. The problem, Chevrolet stated, could be with the motor, the gearbox, or something else. You will have to pay a dealership to have it inspected, but either way, this is a factory item, and only the complete steering assembly is sold. You cannot buy individual parts, such as the DC motor. Chevrolet "investigated" and refused to honor the warranty on this "individual" failure. It refused to provide me an email address so I could send it links to the thousands of reported cases.

I work for an electric motor distributor, and I develop and provide training on motors to our sales force. So I am very familiar with DC motors. It seemed to me that the most plausible reason for failure was with the DC motor. I added wires to the motor connection, connected to my voltmeter, and found that the 12V DC power to the motor did not vary when the power steering failed. Therefore, the problem was not in the power to the motor. I was also able to find a point when the motor did stop working. I did more research online and found that the average cost for the complete assembly replacement was $3,500. I also found that another technician had identified the DC motor as the culprit.

After searching on eBay, I found a complete new assembly for $300. I purchased this and replaced the motor. I then disassembled the original motor and found that the brush springs were insufficient in wire diameter and turns. They did not even give the amount of force that a pen spring has. These springs push the brushes against the motor armature (transferring the DC power to the motor's rotating shaft).

They were so small and weak that the motor brushes wore unevenly and actually caused them to bind into the brush holders. I would never have thought anyone would have considered using something so weak in such a critical component. I sanded the brushes flat, slightly stretched the springs to give additional tension, put the motor back together, and tested it. It now worked as it should. The issue is cost savings in the springs for the motor brushes -- probably a fraction of a cent, at most -- which translated into thousands of dollars for the consumer, not counting towing and rental car fees.

In 2010, Chevrolet had a recall on this problem. It would only inspect and replace any existing defects. If you paid to have the problems fixed, it offered no compensation. After five years, most of these parts would already have been replaced. I now have a spare motor and will hang on to it until she sells the car.

This entry was submitted by Rob Horton and edited by Rob Spiegel.

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About the Author(s)

Rob Spiegel

Rob Spiegel serves as a senior editor for Design News. He started with Design News in 2002 as a freelancer and hired on full-time in 2011. He covers automation, manufacturing, 3D printing, robotics, AI, and more.

Prior to Design News, he worked as a senior editor for Electronic News and Ecommerce Business. He has contributed to a wide range of industrial technology publications, including Automation World, Supply Chain Management Review, and Logistics Management. He is the author of six books.

Before covering technology, Rob spent 10 years as publisher and owner of Chile Pepper Magazine, a national consumer food publication.

As well as writing for Design News, Rob also participates in IME shows, webinars, and ebooks.

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