That's not true. You don't have to do a chemical analysis of the metal
(which actually will likely give you very little information of value
anyway). Of far more importance when dealing with metal is the
crystalline structure.

The crystal structure can reveal flaws that will lead to failure. It
can reveal nonhomogenous composition. Depending on the nature of the
material crystal structure can sometimes be revealed by patterns.
Analysis of meteorites, for example is done by polishing the surface
and then etching with acid. In industrial applications spectroscopic
imaging tends to be used. Rotors being cast, should have a crystal
lattice that is revealable. Forged metals tend to reduce the size of
the crystals (removing the gaps in the crystalline structure, and
improving the strength of the forged material.)

You have continued to claim that your rotors are "bad", without
describing that nature of the problem (other than "rust", which is
perfectly normal on rotors.) Are the rotors warped? Are they cracked?
Are they out of balance? If so how did you determine they were out of
balance? Wear patterns can often times be extremely illuminating, hence
why pictures are valuable.

While state inspections vary, most places are concerned with.1)  Do the
brakes work? 2) Are the materials within tolerances? 3) And are the
materials up to the standards of the day (not necessarily TODAY's
standards, but the standards of the original manufacture date of the
vehicle.) Tolerances are measured (hence the micrometer measurements.)
Standards for the rotor are usually resolved by visual inspection.
Hence the need for a picture.

If your rotors are rusty on either wear surface after having driven the
vehicle to the end of the block and back. The Rotors are probably NOT
the problem. The calipers and pads need to be checked out. The pads
should be in contact with the rotor. The caliper should move back and
forth. The piston should respond to the brake pedal.

On the other paw, if you have rust cracks WITHIN the rotor (as opposed
to just on the surface), that could be a sign of a faulty rotor. Again,
a picture would resolve that issue very easily.

On Aug 16, 2004, at 3:27 PM, Eric Zeno wrote:

>      The only way to tell if the manufacture cut corners
> in the alloy in the materials is to do a chemical analysis
> of the material. Obviously I'm not going to do this.