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5000 brake mods contemplated

This morning, while clearing out some of the BMW effluvia that's cluttering
up my "shop" (it's actually a 10x25 storage room a few miles from my house),
I noticed the brake rotors from my old 530i are the same thickness as those
on my '87 5000 ... I also noticed the calipers have four 40mm pistons (this
works out to approx. 10% more piston area) and similar sized (but different
shaped) brake pads and they don't seem to be much heavier than the floating
type calipers Audi used.

Assuming they can be made to fit easily enough, this looks like it might be
a cheap but effective improvement.  BMW also used 11.0" x 22mm rotors on at
least some cars (mid-'80s 6 and 7 series) as well as vented rear rotors and
while the bolt pattern is different (5x120mm), they can be redrilled easily
and racing experience has shown this doesn't cause any reliability problems.

Mind you, I'm perfectly happy with the brakes as is (Repco metalmaster pads,
ss-braided teflon brake lines) but as an inveterate tinkerer with all things
electro-mechanical, this seems like a very tempting idea, especially since I
already have most of the parts I'd need on hand.

Does anyone know the diameter of the various master cylinders Audi's used on
the 5000 over the years?  I want to see how they compare with the one on the
530i so I can calculate whether this will need to be changed as well and I'd
prefer NOT to tear my car apart just to take measurements.

BTW, the rear calipers use 42mm pistons and vented rotors are available from
10.2" to 11.2" dia. ... I don't think I need that much rear brake on my 5000
(fwd) but you Quattro folks might find it useful.  Just thinkin'...

                /| | | |\  |   |\  | | |\  |  AudiDudi@delphi.com
               /-| | | | | | = | | | | | | |  Jeffrey Goggin
              /  | |_| |/  |   |/  |_| |/  |  Scottsdale, Arizona