|
For the number of times you may need a dial indicator micrometer you might want to try borrowing one or begging a friend to come over for a brew and "show you how it's done". Some people (like me) don't like lending out their precision instruments.
Because runout tolerances are pretty small, any movement of the suspension can make things look worse than they are (even from something as slight as hand turning the rotor). For this reason be sure to anchor the (magnetic) base to the axle or suspension rather than the car body or something sitting on the ground. Be sure that the rotor is torqued down evenly to spec (using sleeves or large nuts as spacers) when measuring runout. Runout is measured approximately 1/2" from the outer edge of the rotor. A purest will measure runout on both the inside and outside of the rotor looking for the worst case. Minor runout on the rear rotors can often be minimized by shimming strips of foil between the rotor and the hub. Runout can also be changed by re-orienting the rotor on the hub studs (altering the combined effect of rotor and hub rounout), but that would mean doing away with the wheel alignment pin.
Just as important as runout, maybe even more so, is the minimum thickness and uniformity of thickness around the rotor. For that you need a caliper (sleeve) micrometer. Measure rotor thickness at a number of points around the rotor and compare the minimum to the spec (stamped on the back side of the rotor) and compare the maximum variation (difference between the thinnest and thickest spots) to the spec for your particular type of brake. Other than factory manuals and the pocket service guide, specs are sometimes hard to come by, but I found mine in a Chilton's manual.
--
Dave -not to be confused with a real expert, just goofing around at this
|
