This is garbage and not appropriate for street (m) (archive)

I don't normally flame people who post to public message boards, but the advertisement for cross drilled rotors was particularly galling to me since it advertises a product that is unsafe for street cars and it falsely claims that Porsche uses them. I should probably wait an hour before I post this but ...

Let's be very clear about this. Porsche uses stainless steel rotors that have 4mm holes cast in them. They are NOT crossdrilled. This prevents the buildup of stress risers at the sharp edges of the holes and does not disturb the metal grain flow. Thus Porsche "crossdrilled" rotors are not prone to cracking.

The advertised rotors are OEM cast iron rotors with 8mm (or larger) holes drilled in them. That makes them prone to cracking.

The advertisement claims longer rotor and caliper life. That is a FALSE claim. Drilled rotors have shorter lives and there should be no impact on the caliper life. What the ad fails to mention is that the pad life will be shortened slightly.

The add claims up to three times the life of a standard rotor. Again, that is simply crap. Drilling a rotor will SHORTEN its life. Not prolong it.

Improved stopping power is claimed. Again FALSE. The only time there may be improved stopping power is in wet driving conditions for that brief moment when you first apply the brakes. Drilled rotors (or Porsche cast rotors) do have better initial braking power in the wet because the water and the evaporating gasses have someplace to go.

Greater safety is claimed. FALSE! Unless you plan to take your wheels off every morning and inspect the drilled rotors for hairline cracks before driving, then you have no business installing these on your street car.

Dave Z.

Follow Ups:

Dave, Do you know... MarkM5FtLauderdale 17:40 12/29/2000 (3)
- Are MOVITs cast or drilled? SteveB 18:35 12/29/2000 (2)
  - The MOV'IT kits use OEM Porsche cast rotors David Zeckhausen 20:05 12/29/2000 (1)
    - Porsche rotors have bosses cast in to reinforce (M JEM 11:45 12/30/2000 (0)

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