Hanging rear caliper Bernie says:

[Bernie Benz]

From: SuffolkD at aol.com

Bernie:  Just like a dowell extended far out of its hole, or any cylindrical
object pushed far enough out of its bore: will droop, sag,
whatever....that's physics.  Period.
BS, Scott!   You must believe that gravity sucks it askew.  The piston will
always align itself perpendicular with the pad's backing plate, a large
contact area.

Furthermore, the quattro123.com link (
http://www.quattro123.com/200Brakes.htm) shows the internals of the caliper
and the coarse grooved "Thread" the piston winds in on.  No mystery
there......... Piston too far out and aligning the piston onto the "coarse
grooved "Thread"" is why the piston is hard to push back in, why its needed
to be "screwed" back in and why some people ake them off the car to a vise
for alignment during R&R.....................aligning the threads is a
challenge because its not a standard fine thread..........................
The metalnerd.com and similar Audi brake tools work well when the piston
isn't pushed too far out. Why DFI IAB isn't the best advice here IMHO.
Oh, Scott!  Believe what you wish, but the the E-brake nut within the
caliper piston is purposefully a floating nut relative to piston to bore
alignment, and thus it has no effect on this alignment.

Bernie
 
-Scott by BOSTON 

In a message dated 4/18/2005 12:01:14 AM Eastern Daylight Time,
b.benz at charter.net writes:
From: SuffolkD at aol.com
snip. 
Similarly, the piston when extended far out at near full travel will droop,
or cock out of alignment.  Seen that one.

Seen that one maybe, Scott, but IMO likely a wrong
conclusion on your part.  The piston is not guided by the caliper bore at
all, it is only suspended by the bore O-ring seal and its face contact with
the 
pad backing plate surface.  Therefore, the piston could only cock if the
pad were to wear out of parallel with the backing plate surface to a high
degree, i.e. a highly tapered pad.  A most unlikely and self correcting
condition, one sufficient to cause piston contact and jamming within the
caliper 
bore.  More likely, just a sludged up hydraulic system.  Fix it, it
ain't broke! 

Bernie