Be certain all parts are compatible

Question:

I read your and Ron Lubovich’s discussion in the June issue about putting a 1997 power steering system on a 1939 Plymouth. All your points were well taken. When I reached your comment pointing out it was a power steering rack it made me recall a similar incident of my own. I installed a modern power steering rack on a 1954 Chevrolet and it looked and worked beautifully, until at speed. The action of the steering at first seemed like it was too light and would react to potholes and ruts in the road. As the speed of the car increased it worsened. I had the front of the car up with jack stands on the frame with the suspension at the end of travel just looking at what might be the cause when my mechanic came in. He took one look and said “bump steer.” Then pointed out that the steering rods and the A arms were at different angles compared to each other. Bump Steer, when the suspension went up and down the wheels would turn (steer) in opposition to one another. This caused the sensation of the car as steering too quickly or abruptly. He said that it is a common oversight when dissimilar steering components are utilized without being careful to match the travel angle of the steering arms to the A arms. When we realigned the two, the steering was perfect. It did at first seem or feel as though the power steering was too sensitive. Hence my additional comment to Ron’s question and your answer.

Answer:

Thank you for taking the time to share your experience with fellow Auto Restorer readers. Your story illustrates the point that there is some peril inherent in mixing and matching components when restoring or updating a vintage car. When dealing with steering, brakes, suspension or any other systems that affect safety it’s especially important to be mindful of the need to maintain compatibility among parts.