Controlling on-vehicle rotor runout is becoming increasingly important to minimize DTV (disc thickness variation) and its associated brake roughness warranty complaints.
To prevent roughness from occurring after high mileage, the on-vehicle rotor runout produced from the combined effects of assembling the wheel end components together on the vehicle generally should be 50 microns (0.050mm), or less. High runout still exists on some vehicles, even though individual component runouts have been significantly reduced over the last 10 years. In some cases, by simply mounting the wheel and tightening the wheel nuts, the runout of a low runout hub and rotor assembly can increase by more than 400 microns.
To achieve low on-vehicle runout, it is therefore necessary to consider all elements that can affect runout together as a full “system.”
This paper describes the many factors that can contribute to runout, and outlines a system approach that can be used to develop complete systems that achieve low on-vehicle runout.