My first car was a modified '72 510. After some tuning, the car was very fast and couldn't be more balanced if I had tried applying Feng Shui. My friends and I had a special road that we affectionately called the Nurburgring. It twisted relentlessly through the Northwest forest, graced with elevation changes, narrowing radius turns and off-camber corners trying to feed you to hungry ditches with deep bellies. There was a section that was similar to the Foxhole at the 'Ring, a steep downhill followed by a sharp rise, all the while making a sweeping left. It was great fun to feel the g-forces in my friend's Alfa Romeo, but piloting the old 510 through this obstacle was another story all together. The drop was exhilarating, but when the suspension compressed at the base of the dip, the steering wheel went one way and the car went another. YIKES!!!

"The drop was exhilarating, but when the suspension compressed at the base of the dip, the steering wheel went one way and the car went another. YIKES!!!"

If you have experienced excessive bumpsteer like I have, you have probably had a 'moment' or two that you will never forget, no matter how hard you try. There are others who have experienced bumpsteer and never knew what it was. It is usually felt while cornering and may seem like soft dampers, or even like a rut in the road that wants to pull the car one way or another. It is rarely checked on road going vehicles, as the inefficiencies of mass production make a more noticeable difference in handling than a little bump steer. Besides, engineers are currently doing their best to take bumpsteer out of the car during the design phase. On a modified car, or a car built specifically for racing, bump steer in one of the first elements of the suspension that is tested and tuned.

Bumpsteer is simply the change in toe as the suspension travels. If the steering rack and linkage is not in an optimal position in relation to the rest of the suspension, distances become too short or long and angles become askew causing the wheels to point in the wrong direction when in motion. When modifying a suspension by lowering the car or relocating control arms, the tie rods and control arms are not always working harmoniously and modifications need to be made. These modifications usually come in the form of spacers to relocate the steering rack or steering knuckle.

If used in moderation, a professional can add a small amount of bumpsteer to help fine-tune the attitude of a car in a corner. For example, if a properly tuned car still tends to understeer upon turn in, a few thousandths change in toe in the first couple inches of bump can alter slip angles enough to stabilize the front end of the car.

Any adjustment to the suspension is best left to a professional, as there are special instruments needed to measure and correct issues you may have. To help minimize bumpsteer without reengineering the suspension, installing polyurethane control arm and steering rack bushings will help keep critical pieces from moving in relation to each other. This will help maintain the set geometry and make the car more predictable.

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