A very common cause of excessive NVH (Noise, Vibration, and Harshness) in modern automobiles is tire and wheel assemblies that do not have an equal distribution of mass, or the center of mass is out of alignment with the axis of rotation. As a wheel becomes more unbalanced, or the distribution of mass on the wheel assembly becomes unequal, the driver may notice an increase in vibration, oscillations of the steering wheel, and noise, which will often be directly proportional with vehicle speed. This can lead to impaired drivability, and eventually will increase the wear rate of the tires – not to mention most drivers don’t particularly enjoy lots of vibrations in their vehicles.
Wheel assembly imbalance can occur for a variety of reasons. As a mass-produced item, it is nearly impossible for tire and wheel manufacturers to produce completely balanced parts. This is to be expected. Bent or damaged wheels and tires are another common cause of wheel imbalance but are often much more difficult to remedy.
The most common solution to fix wheel assembly imbalance and reduce NVH to acceptable levels, is the use of a wheel balancing machine. Over the years, a variety of different solutions for balancing wheels have been used. Modern wheel balancers are complex pieces of equipment that rotate the wheel assembly at a high rate and use 2 or more force transducers to measure the forces exerted onto the axis of rotation. The machine then uses complicated mathematical formulas to determine the precise location of the imbalance, and the amount of weight that should be added to fix it. Some modern balancing machines will also apply force to the tire tread and sidewall to measure for any uneven tire deflection, allowing technicians to correct that as well.
With any piece of precision metrology equipment, it is important to properly maintain your wheel balancer and only use high quality parts. An improperly maintained balancing machine can lead to wheels being balanced incorrectly. This leads to more customer come-backs, and more time and money spent trying to make sure the customer is satisfied.
The first and most important step in balancing a wheel and tire assembly is removing any existing wheel weights. If the wheel has adhesive wheel weights, it is also incredibly important to remove any adhesive residue that may have been left on the inside of the rim. MT-RSR has a variety of tools and solutions for removing both wheel weights and their adhesive. Many wheel weight tools are also used to install new wheel weights to complete the balancing procedure.
The second step in balancing most wheel and tire assemblies is choosing the correct cone or collet. MT-RSR recommends choosing collets over cones, as collets have a lower taper and will fit wheels with tighter geometry around the hub. The collet or cone must be sized to fit in the bore of the wheel, with the mating surface on the wheel bore hitting as close to halfway as possible down the taper on the cone or collet.
If the wheel you are balancing comes from a vehicle that is ‘lug-centric’ rather than ‘hub-centric’, or has plastic clad wheels, then it is important to also shop for a Pin Plate or SpeedPlate system. Pin Plates and SpeedPlates both achieve the same goal, of providing a centering and clamping force to the front of the wheel assembly. MT-RSR’s SpeedPlate system is a fast, reliable, and durable way to balance those problem tires. The SpeedPlate system can also be ordered with the AutoClamp Handle, which allows it to be used on balancers that use an AutoClamp or SpeedClamp instead of a traditional threaded shaft.
To get a proper balancer reading, without any preventable movement or additional forces, one must use a hub nut and pressure cup to apply force to either the face of the wheel itself, or to the SpeedPlate system accompanying it. MT-RSR has a wide selection of Quick Nuts, Speed Nuts, and Pressure Cups that will fit most brands and models of wheel balancing machines.
Once the balancer has ran and has been able to measure the amount of imbalance, the technician is then able to apply the wheel weights in the correct location. MT-RSR has a wide range of adhesive wheel weights, which only require a clean wheel surface to be installed. Bang-on/Hammer-on/Clip-on wheel weights are also available.
Ensure your wheel balancer machine is running smoothly and accurately, with high quality MT-RSR replacement parts! For more information on proper balancing techniques, check out our previous ShopTalk blog post!