Bob talking with Greg

Every manufacturer has tolerances, this is necessary to accommodate assembly line efficiency. When a machining process first takes place the cutting tool is new and sharp, the tolerances are the best they can be. As the day goes on, the tool wears, tolerances get looser, but not to the point of compromising the product. We're not talking but thousandths of an inch. The really smart people have figured out how many pieces can be machined before a tool needs to be replaced or sharpened. This is why there are tolerances in manufacturing, and why not every thing is exactly the same.
     As wheels and hubs go through the machining process the tolerances are kept within spec, but there are variations in the machined areas of these products. This variation can cause a vibration or a shimmy, maybe an out of round feeling at the wheel end. This is where you come in, getting it right from the start.

Having the wheel bearings checked for proper adjustment is the place to start when looking for vibration / shimmy issues. Getting them adjusted will eliminate that part of the wheel end assembly as an issue.
Taking care of a vibration could be as simple as balancing the tires. When putting on tires, and i'm talking about all tires, drives and steers, they should be balanced, they're not perfect and need a little help. Hunter Engineering now has a balancer, the Force Match HD, that will not only balance a tire, including wide singles, it will find the high and low spots of the wheel and the tire. With the highs and lows found, one can turn the tire on the wheel to match up the high of the tire with the low of the wheel and get the roundest assembly possible. This is important because an out of round tire can be balanced. It will ride like it's not round and it will wear faster, also causing other parts of the truck to wear faster, but it can be balanced.
Once you have them balanced, they need help staying balanced. Any bit of mud or asphalt can cause an out of balance condition. A dynamic wheel balancer helps keep the wheel, tire, hub, and brake drum assembly in balance while the truck is moving. Centramatic and Balance Masters are two brands of dynamic balancers for trucks.
Ok the vibration is balanced out but we still have a wheel "hop". Since the tire was checked for out of round and is mounted properly, we then think about the machining process and the tolerances; this may be where the problem comes from. Using a product called Tru-Balance, the name is deceiving because it doesn't balance anything, will center the wheel to the wheel stud instead of using the hub to pilot the wheel, stopping most wheel "hop" complaints.
A misalignment condition can lead to irregular tire wear that can cause a shimmy. I have just had our truck alaigned at the TA in Foristell Mo., shop manager Aaron Click, techs Jake and Randy were great to work with, using the Hunter Engineering equipment they have, I got a three axle alignment, and I couldn't be happier. Since Hunter Engineering is located in the St. Louis area, Hunter Engineering Heavy Duty Equipment Specialist, Greg Brock was there to demonstrate the Force Match HD wheel balancer, using our wheel/tire assemblies to show the techs at TA what a great addition this machine would be to thier shop. TA has this machine at 3 locations, TA Brookville, Pa, TA Morris, Il, and TA New Braunfels, TX.. Stop in, get an alignment and have your tires ballanced, see if it makes a difference in your ride.

Bottom line,
 Get the alignment checked each time you do any suspension work or if your tires are wearing oddly.
 Balance the tires every time they are removed from the wheels.
 Use a dynamic balancer to help with rolling balancing.
 Use the Tru-Balance centering sleeves to center the wheel to the wheel stud.    

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Very interesting article Bob. My water tender rides a little rough to begin with and tire longevity isn't something that is possible on the "roads" we run. The various sizes of gravel, round and sharp are murder on tires. But this is very interesting. In my 1 ton pickup I have a hop between 39 and 41 mph. It goes away below and above that speed. I haven't been able to find the cause but I wonder if high and low spots on the wheels and tires could be the cause. I have them rotated and balanced regularly but can't seem to stop the Ford 40 mph hop. I know it doesn't have anything to do with class 8 trucks but it's still very useful information. Thank you.

August 20, 2013 8:43:13 AM