UFO conversion options

C1J1Miller at aol.com C1J1Miller at aol.com
Thu Sep 26 16:35:44 EDT 2002

In a message dated Thu, 26 Sep 2002 1:23:23 PM Eastern Standard Time, Bernie Benz <b.m.benz at prodigy.net> writes:

>Hi Chris, good to hear from you.
>Braking surface rotor corrosion I am not fimilar with but, from a materials
>and operating conditions standpoint, I can not understand why the inner and
>outer annular rings of the surface would be more suseptable to surface
>corosion than is the center ring.  Any wild ideas?

The outer edge of the rotor is not swept by the pad; rust starts and then spreads like a cancer.  It appears like it spreads beneath the visible surface of the rotor...

>As to the center annular ring doing all the braking, I don't believe it.
>Apparently as you describe it, the rust is firmly attached to the base metal
>of the rusted areas, possibly having a rougher surface and thus a
>higher/different coeff. of friction against the pad.  If so, initial pad
>wear in the rusted areas will be greater than in the center, but only
>momentarily, until the contact unit pressure against the rusted areas is
>reduced enough that pad wear is equalized in the two different friction
>areas.  The total rotor surface is now equally effective.  Pad wear may be
>greater overall because of the modified surface, the only negative IMO.

The rusted area is quickly polished; if you scrape at it, the center unrusted area is very hard, and is not affected by the scraper; the outer shiny metal looking part flakes off exposing the true metal surface... perhaps I'm not explaining what I've observed very well.

Also seems to have a different coefficient of friction than the true metal surface of the rotor; stopping distances appear to increase.  I'm wondering if the rusted portion is not just rust, but some combination of rust and deposited pad material???

>Cad, or even chrome plating the active rotor surface, IMO, would be a
>waisted effort.  Cad is too soft, and both are too thin  <<.001" to provide
>a lasting surface.  Better, select a more corrosion resistant casting
>material for the rotor, but this apparently is not cost effective for the

The cad plating would stop the rust in the areas of the rotor where the pads do not contact the rotor (outer edge where the hat attaches, corresponding inner edge, and vent areas).


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