Suspension Issues?

Altered suspension? You’re probably no stranger to on road drivability issues. We should probably discuss terms and definitions before we get into it.

A. Bumpsteer: most noticeable when cruising down the freeway at high rates of speed. You drive over an overpass; the quality road work causes a gradual bump in the highway. As you hit the bump, the steering wheel shifts to the right, then just as suddenly it goes back to the left as the jeep rebounds from full suspension compression. This scenario causes an unwanted and unexpected lane change. Yeah, it’ll get your attention as well as those to either side of you on the freeway.

A quick safe way to test for bump steer is to drive to a parking lot or somewhere you can stop and start without causing as accident. Start with the steering wheel straight. Nail the throttle, then immediately stand on the brake. As the front end drop, hit the gas again. This will cause the front end to drop, compressing, then lifting the front suspension. Take a look at the steering wheel while performing the whole brake/gas thing. If it is rotating or turning side to side, welcome to the world of bump steer. If it stays pretty much centered you’re probably good to go.

B. Wandering: noticeable at any speed, but generally worse at higher speeds. While maintaining the steering wheel in straight and level flight position, the vehicle darts and follows every rut and crack in the road. Trying to correct for the “wandering” vehicle often results in over steer or over compensation with a disastrous outcome. This wandering condition is often symptomatic of tight steering. Turn to the left, let go of the wheel, it keeps going left. Turn right; it keeps going to the right, with no return to center properties evident. Extremely loose steering will also cause wandering due to the inability to control the front tires movement. We’ll discuss causes and remedies in future articles.

C. Death Wobble: (My personal favorite) There’s really nothing like having a soccer mom describe what happened to her Grand Cherokee when she hit a dip in the freeway while in a slight turn at 65 mph. It’s like she is reliving the sheer terror of the event as beads of sweat build on her forehead and her voice shakes with emotion. “The steering wheel started to jerk violently from side to side. I tried to hold to it but there was nothing I could do. I hit the brakes and it got worse. I knew I had to stop, so I stayed on the brakes. I thought it would break my arms. It finally subsided when we came to a complete stop in the middle of the freeway.” I then say, (sympathetically), oh, you’ve just experienced “death wobble”, she nods knowing and replies, “yes, that is exactly what it was! We were nearly killed.” Most people who experience Death Wobble for the first time think they are the only one to have had this horrific experience. Surely an event of this magnitude would have been on the news if anyone else had experienced it. But alas, it’s quite common. If you’ve had death wobble, you know it. If you have to ask, you haven’t experienced it. This condition is very hard on front end components, not to mention the driver’s nerves. Some vehicles “go off” unprovoked and at random. Others require a small bump, just the wrong speed, or just the right combination of speed, turn, bump. This condition can be corrected. Sometimes easily, often times with much trial and tribulation.

D. Pulling: This one is easy. Let go of the steering wheel. You wind up in the ditch. Constant pressure is required on the steering wheel to compensate for the continuous annoying drift or pull of the vehicle to one side or the other.

E. Vibration: No you don’t need an alignment. We’ll address this in another article.

Dennis Wood

TeraFlex PLUS
5241 Commerce Dr.
Murray, Utah 84107-4711
Phone/801.713.3314
Toll Free/1.800.388.5337
Fax/801.266.4947