More than 250,000 soldiers were wounded in WWII. Some of them could not operate a car using the normal controls. Car makers and shops realized that they had a debt to pay to these veterans. When new cars could be bought after the war, just about every automaker offered hand controls at no extra cost.
Let’s say a vehicle had .003″ of lateral runout when measured at the outside face of the rotor. If this vehicle is riding on 205/55R16 tires, in one mile, the high-spot with .003″ of runout goes past the caliper approximately 836 times. Over 6,000 miles, that spot on the rotor will go past the pads more than 5 million times. Every time this spot passes the pads, a little bit of the rotor’s material is removed. Over the course of those 5 million revolutions, enough material is removed to create a thickness variation that can be felt by the driver. This is why it is critical to measure thickness and runout in a brake rotor and wheel flange even if new rotors are going to be installed.
Troubleshooting an automatic transmission can be one of the most intimidating diagnostic procedures at a shop. The first reaction is typically, “We don’t do that type of work.” But there is profit in performing drivetrain diagnostics and “in-the-car” repairs.