Exploding Rotors: why you do not drill

Brett Dikeman brett at cloud9.net
Mon Jun 23 20:51:27 EDT 2003

At 7:56 AM -0500 6/23/03, Steve Marinello wrote:

>People have run these things for years.  First time I have, preferring solid
>discs, except for the Porsche rotors on the avant.  This should be viewed as
>a single anomaly, for whatever reason it occurred.

The reason is not important- nor is it a "single anomaly"(since the
exact same thing happened to a TT at an event last year, and there
may be other less severe cases).  Two incidences sound like a low
number, until you realize that 95%+ of the people coming to these DE
events don't run cross-drilled rotors(having tech'd most of the
student cars for the NEQ event, I can say that with some certainty).
The failure rate is much higher than you think.

>   A dragging caliper and
>the lack of post/pre run inspection have both been raised as possible
>reasons for the occurence, and I concur.  Drilled rotors will crack,
>eventually, the time to do so varying with use and conditions.  Okay.   SO?

SO, solid rotors don't disintegrate!  Solid rotors are pretty
foolproof.  You can overheat them like crazy and they won't do much
except warp and glaze over, right?  They certainly won't explode in a
shower of metal and take out the caliper, wheel, tire, and brake

Everyone goes to a lot of effort to make sure people are safe
on-track.  A brake rotor that is intolerante of heat/abuse is
completely unsuitable for driver ed events, where many participants
are showing up with powerful cars, often chipped- and no clue on how
to drive them properly(ie, well within the vehicle's limits).

>You use them, you accept the responsibility to check them out.

...and people don't know to check, because vendors/manufacturers
aren't telling them to, because that would be admitting to
making/selling a defective product.

>..or you should stick to stock brake systems completely.


>One more thing.  Although the slotted rotors are appealing for the degassing
>advantage supposedly, most pads have slots that do that job.  And the other
>disadvantage of slotted or drilled rotors is the accelerated pad wear.

Uunless you get your brakes very, very hot-  "degassing" isn't
necessary.  It's a race technology. Race != use on street for better

It's like poly bushings and all manner of other little "race" parts-
they make so little difference it's not even funny- and besides, DE
events are about learning to drive, not going as fast as you can.

"They that give up essential liberty to obtain temporary
safety deserve neither liberty nor safety." - Ben Franklin

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