UFO problems

[Bernie Benz]

Peter,

I'd rule out rotors first.

Do you have access to a dial indicator?  If so, check your rotor runout
first.  If not, jurry rig a pointer attached to the caliper mounting to
eyeball rotor run out.  While doing this check for wheel bearing looseness
which can contribute to apparent rotor run out.

I don't know about aftermarket rotors, but OE rotors had the actual new
runout measurement etched into the mounting surface.
Make sure that the hub and rotor interface surfaces are clean.

Have you tried the "80/20 warp 'em back straight" technique touted by some
on the list?  I'm skeptical about this one working, but have never had a
reason to try it.

Here is another technique that I've used sucessfully on a 5K and other cars
with badly warped rotors.  Shim them true.  If you can quantify the high and
low points of the runout and the total runout with the dial indicator, you
can calculate and cut paper shims of the approperate thicknesses for 3 or 4
of the bolt holes, install and remeasure.  Maybe a little more work on UFOs
than conv rotors, but you can get them dead on if persistant.

I looked into lower CA bushings and ball joints when I was tracking down
excessive negative camber.  Went so far as to remove the apparently perfect
inner bushing and reinstall it flipped and rotated 180d, which should have
altered camber sugnifficantly, it they were the problem. No change, so not
problem there, and I find it difficult to believe that these are problem
areas at the low mileage that Bentley claims, was their suggestion 50K +,
replace?

Bernie

> From: Peter Schulz <peschulz at cisco.com>
> Date: Thu, 13 Jun 2002 13:52:06 -0400
> To: "Freed, David (Exchange)" <dfreed at bear.com>
> Cc: "'200q20v at audifans.com'" <200q20v at audifans.com>
> Subject: Re: New Member, Not a new Audi owner
>
> Dave, et al:
>
> The Bentley manual has a few pages that discuss dealing with UFO braking
> issues.
>
> Both the wagons display opposite ends of the UFO performance spectrum
> - the 168 kmile Indigo Mica wagon's UFOs work wonderfully, not pulsing
> whatsoever.
>
> -the 170 kmile Titan grey wagon has brand spankin' new UFOS and pads,
> courtesy of the previous owner
> (I have the invoice $448 for rotors.  OUCH!)
> Braking behavior is best described as violent - the steering wheel moves
> back and forth with great prejudice.
>
> My next move is to try a spare set of front lower control arms with new
> bushings
> - an area which Bentley and Audi advised as being a potential problem.
>
> -Peter
>
> At 01:03 PM 6/13/2002 -0400, Freed, David (Exchange) wrote: