[200q20v] Re: [V8] just out of curiosity (UFO question)...
pjrose at frontiernet.net
Thu Feb 1 10:19:29 EST 2001
A couple of listers (Graydon Stuckey and Jeff Bernstein) responded to
my query with their guesses, which happen to agree with my own,
secret guess--which I hadn't been confident enought to mention,
fearing jeers of derision... :-) Chris Miller claims he's found
Audi's own description of the device--where, Chris? Maybe it's in the
Album, I didn't look there.
Graydon wins (yeh, a new S8, that's the ticket) for being first with
a correct answer.
So--the conclusion is that this "thing"** is a "vibration damper",
i.e., a counterweight used/needed to alter the resonant frequency of
the caliper. Well, then that seems to tell us that Audi knew there
was a special "problem" with the UFO design pretty much right out of
the box, so-to-speak.
Now, I wonder if it's possible for a significant part of certain UFO
vibration problems to be treated by modification of that caliper
damping device? Sure, it would be best to have a perfect, non-warped
rotor, but assuming some warpage is unavoidable, could vibration be
further "supressed" to any useful extent by "tuning" the damper with
some additional weight? Has anyone tried that? Possibly it would be
easier to completely remove the thing and check if the problem
actually worsens. I assume it unscrews from the caliper body.
Also, if this damper is effective (and would Audi ever do something
that's ineffective?), then owners would be well-advised to verify
that it doesn't "go missing" or become damaged (bent).
** We might call this (pending approval by the ISO) the "UFO damper",
unless Audi already has assigned it a convenient name.
At 3:39 PM -0500 1/31/01, Phil Rose wrote:
>Yesterday I was kibbitzing with a local Audi wrench (small-shop guy who
>likes to chat) while he completed a CV boot replacement on a '90 V8. While
>I was examining the UFO brake I noticed a strange-looking appendage (seemed
>to be stainless) which stuck out horizontally near the top (inside) end of
>the caliper. It has a thin shaft (tube?) that's about 1.5" long and it
>terminates in round, flat-ended "knob" of about 3/4" diameter.
>"Whazzzaaaat?", I asked.
>He smiled, and replied, "You tell me. I've been wondering for years about
>I looked in my Bentley and could see the "thing" clearly drawn in several
>UFO caliper diagrams, but there didn't seem to be any notation as to it's
>name or function.
>Anyone have a clue?
>whose '91 200q doesn't even have UFO brakes
>mailto:pjrose at frontiernet.net
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mailto:pjrose at frontiernet.net
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