Re: Drilling Break Rotors

[Porsray@aol.com]

>From my experience with the drilled rotors on a Porsche Turbo and 
from reading some tech discussions in the Porsche archives, might
want to be cautious.

1) While drilling increases brake cooling, it also decreases rotor
and pad life.  The drilling causes increase stress in the rotors, especially
at the drilled holes.  I went through a few rotors due to cracks starting
and progressing from one hole to the other.

2) Holes must be drilled so that you avoid the webbing.  Actual pattern
as far as I can tell varies with the webbing design; the Porsche had the 
holes equidistant form each rib.

3) Holes must be chamfered to reduce stress buildup.  Also, there 
must not be any burrs in the surface from the drilling.

4) I would also think that the heat buildup from the drill bit would change
the metal properties at each hole, potentially inducing a prestressed
condition at each hole.

5) From what I have heard, the drilled and solid factory Porsche rotors are 
NOT the same material.

ope this helps, Good Luck!

Ray calvo (porsray@aol.com)
1990 Coupe Quattro


In a message dated 97-04-02 21:53:39 EST, you write:

<< 
  
 I have the capability to drill my own break rotors at home (Brother is as
 psycho as me, he is building a fairly large working steam locomotive so he
 has a lathe and mill).   What I want to know is other than cad-plating is
 there any magic that manufactorers of drilled break rotors use.  Looking at
 pictures in various magazines it looks like most use a 30 degree spacing.
  are they carefull of the webbing inside vented disks?  Thanks for any
 insight anybody might have out there.
 
 Jim
 '87 5KTq (IA stage II, Fuchs Wheels, Euro Lights)
 '84 Ur-q (TAP BOX, 8" Wheels, Big Exhaust,Springs, Bushings) in need of a
 clutch
  >>