UFO Rotors - $$

[Tom Mullane]

Bernie,

The current issue is not warpage, but rust.  Parts of the contact surface of
the rotor have rusted; or rather, it seems like the contact surface is too
hard for water to penetrate, but it kind of gets "behind" the shiny, glazed
surface and causes a delamination of the rotor where parts actually flake
off.  On the inboard side of the rotor, the pad contacts only a ring about
an inch wide in the center of the contact area. This car sat for months at a
time in a Boston garage between uses, possibly the origin of this
phenomenon.

Thanks for the paper shim tip.  It may be useful it the new rotors have some
runout.

Tom
----- Original Message -----
From: "Bernie Benz" <b.benz at charter.net>
To: "Tom Mullane" <tmullane at snet.net>
Cc: "200q20V mailing list" <200q20v at audifans.com>
Sent: Thursday, May 01, 2003 1:54 PM
Subject: Re: UFO Rotors - $$


> Tom,
>
> IMO rotors, UFO or otherwise, should not be turned unless they are badly
> warped, inasmuch as they tend to wear true and therefore used rotors will
> always be better than new or machined, warpage not withstanding.  Some on
> this list have talked about a "dewarping procedure" that they have used
> sucessfully, but I've never had the problem so don't know about it.  Rust
> does not contribute to warpage and should not affect the braking surface
> unless the car has been parked below high tide elevation for the winter.
>
> Measure the runout of each rotor, the max spec being <.002"  If you do not
> have access to a dial indicator, A post-it is about .0025", so if stuck to
> the low runout side of the outer breaking dia on the inboard rotor
surface,
> it should not go under a pointer fixed to just touch the high side of the
> runout.  Simple test, I'll bet you'll find no runout problem.  Or, if
> necessary, they can be shimmed into spec with paper shims at the hub
> interface, BTDT on G60s.
>
> But do overhaul your calipers and caliper slides!  A dirty but zero cost
> job, and may well be the cause of your problem.
>
> DFI if IAB,
>
> Bernie Benz
> Gardnerville, NV
>
> '90 90Q-20V  140K
> '91 200Q-20V 140K
> Ford "Quatro" Tractor
> Other Misc. Toys
> > From: "Tom Mullane" <tmullane at snet.net>
> > Date: Thu, 1 May 2003 13:07:02 -0400
> > To: <200q20v at audifans.com>
> > Subject: UFO Rotors - $$
> >
> > This is a multi-part message in MIME format.
> > --
> > [ Picked text/plain from multipart/alternative ]
> > My UFO rotors are suffering from Northeast rust syndrome, causing the
brake
> > pedal to pulsate.  The rotors on the car now are original equipment at
155K,
> > so I have doubts about the feasibility of turning the rotors.  I also
tend to
> > be more of a "while I'm in there anyway I may as well..." preventative
> > maintenance type of guy rather than a BFI if IAB guy.  So will I have
decided
> > to change both pads and rotors, and possibly rebuilding the calipers.
> >
> > After much deliberation, I have decided keep my existing UFO brakes
rather
> > than upgrading.  The factors influencing my decision included some
uncertainty
> > about the length of time that I will own the car, my choice not to use
the car
> > for any track events, and the fact I would like to be able to continue
to run
> > the stock wheels.  (I would like to do some track events, but I am
hoping to
> > acquire a 944 turbo at some point in the future for this purpose.)
>
> > Anyhow, I was surprised at the price of the new UFO's (this was a large
part
> > of my choice to retain the UFO's).  Audi quoted me $272 each for
> > new...surprisingly cheap.  Northside Imports in New Jersey (Bill Maas)
quoted
> > me $198 each for new.  I have dealt with Maas/Northside for years and I
would
> > imagine that their rotors will be identical to the Audi rotors.  Anyone
have a
> > problems with aftermarket versus dealer?  Anyone find a cheaper source
for
> > UFO's?
> >
> > TIA.
> >
> > Tom Mullane
> > 91 200Q
> > 91 CQ
> > 99 A6Q
> > etc.
> >
>
>