Front Rotor Question

Bernie Benz b.benz at
Sun Apr 13 23:04:21 EDT 2003

Any good/acceptable brake rotor should measure >.002" runout on the hub.  If
it measures more than that on the turning lathe, don't assume that the
problem is with the hub!  Most probably it is not!  It must be measured on
the hub before removing, for an absolute determination.  All Audi UFO rotors
have the original runout ingraved on the hub area for your reference.

Most brake lathes are never calibrated nor checked for accuracy, (BTDT), and
their owners get pissed if questioned about this.  So, don't machine your
rotors on a untrue lathe, demand a calibration before any maching!
Owner/wrench won't know what you are talking about, nor how to do it.

Further, all rotors tend to wear true, and therefore used rotors are always
better than new or machined rotors, assuming that they haven't been
subjected to warping circumstances and abuse.  I've not experienced such
circumstances with my UFOs nor conventional G60s.  But either type rotor can
be shimmed to bring it within the >.002 spec, without machining, BTDT.

Good brakes are an inexpensive and beautiful experience!


> From: Kneale Brownson <knotnook at>
> Date: Sun, 13 Apr 2003 19:26:22 -0400
> To: "adelphia" <g_dion at>, <200q20v at>
> Subject: Re: Front Rotor Question
> At 04:02 PM 04/13/2003 -0600, adelphia wrote:
>> Hello
>> I am wondering if the UFO type front rotors for GIRLING brakes can be
>> turned. I can't see how a standard brake machine could get it down.  I am
>> not in a hurry, brakes work just fine, but am curious, and was quoted $272 a
>> piece for new rotors
> Here's one approach:
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