When vibration occurs, something in your vehicle is experiencing excessive wear, that was not intended by the manufacturer. Left unattended, it can mean failure of a vital part at a crucial time with unspeakable consequences. Think about it… you may be driving an RV weighing 7 – 15 tons, at a speed of 55 – 75 miles per hour and something is out of synch badly enough that you can feel it in your comfortable captains chair, while sipping your coffee and talking with your companion.

The most common causes for vibrations in your coach are:

   1.Out of balance tires: Generally speaking, with out of balance tires, the faster you go, the worse it shakes. Out of balance tires ruin bearings, joints and shake screws and bolts loose, as well as fatigue metal faster than anything else you could do. Do you really want to be driving a 10 ton rig down the road with bolts loosening as you go?

   2.Out of round tires: Generally speaking, with out of round tires, it will usually shake worse at a certain speed, and then you can eventually drive through it… but it could be a very high speed before it goes away. But as with out of balance tires, vibration will cause parts of the front end and suspension to wear out more quickly and will cause parts throughout the RV to become loose. You might begin to hear squeaks and rattles that will drive you crazy. It can also cause metal fatigue which will weaken the structure of your coach.

   3.Bad wheels: If the wheel isn’t round, it’s going to affect the tire and how it works. An alloy wheel like an Alcoa is more concentric than a stamped steel wheel. You may have noticed that with more expensive cars, they tend to have alloy wheels, and this is not just for looks. It’s a rounder wheel, so there are fewer problems with out of round conditions, and less road harshness.

   4.Front suspension: I think it’s important at this point to make the distinction between vibration and what we call “shimmy”. If you hit a bump and the steering wheel begins shaking in your hands (sometimes violently) then goes away when you apply the brakes, that’s shimmy, and it’s not a wheel or tire issue. It means something in the front suspension isn’t right—there’s a loose tie rod end, drag link or a worn-out steering damper.

   5.Driveline problems: Driveline problems usually come from the center of the vehicle, and there are several things you can do to determine if it’s driveline related or not. For instance, if it happens on acceleration or deceleration, it’s usually caused by incorrect driveline angle. Driveline vibration can also be caused by a drive shaft that was installed, or re-installed incorrectly.

If a customer comes in with what he thinks is driveline vibration, at Henderson’s Line-Up, we simply put it in Park and bring the engine up to speed. If there’s vibration, we know it’s absolutely not the tires or the driveshaft; it’s the flywheel, harmonic damper, torque converter, or maybe the engine itself. If there’s no vibration in Park, we can take the wheels off completely, put the coach on a lift, and run it up to 60-70 mph. If we don’t get any vibration there, we know the problem is with the wheels and/or tires.

Come back tomorrow for Part 2.