[Shotimes] Re: Shotimes digest, Vol 1 #4450 - 12 msgs

[MonsieurBoo@aol.com]

> The secret as I see it to drilled rotors lasting for street or  competition 
is to chamfer 
> the hole and make the holes smaller... The Chamfer relieves the  stress 
that builds 
> up around the opening that is what creates cracks in most drilled  rotors.
>
>Don Mallinson
 
=============

 

I second that one Don, us old-racing-cycle buffs drill out the stock  plain 
rotors for lightness and we always put nice broad chamfers on  'em precisely to 
avoid those stress cracks.  Also, stagger the holes  like you mentioned so 
the same stress vector doesn't line up through 2 - 3  adjacent holes, but goes 
through "meat" on each side of a hole.  It's not  ALL about how kewl the 
pattern looks <grin>
 
Beats me if any rotors get cast with the holes already in them, but if  so, I 
bet there would be less danger of cracking because the metal grain will  
naturally flow around the holes as it cools.  I'm not so positive you'd  have to 
finish the *cooling/venting* holes either, the roughness would  increase 
surface area and turbulence, might even cool better that way, though  it would 
probably be a brake dust magnet too...
 
Mark LaBarre
94 atx 130k