Exploding Rotors: why you do not drill

[Bob Rossato]

Not to start a thread on pros and cons of drilled rotors but, it is
obvious that these rotors were a home made job.  There is a rudimentary
pattern to the holes but the spacing is all over the place and the holes
look bigger than anything else I've seen.  I'm not defending drilled
rotors but the reason these exploded has a lot more to do with the fact
that some clueless individual just went to town on them with a drill
press without any regard to the size of the holes, amount of material
removed, or balance of the rotor.  If someone is actually selling these
things in this condition then that is downright criminal.

Bob

> -----Original Message-----
> From: quattro-admin at audifans.com
> [mailto:quattro-admin at audifans.com] On Behalf Of Brett Dikeman
> Sent: Friday, June 20, 2003 12:55 AM
> To: quattro at audifans.com
> Subject: Exploding Rotors: why you do not drill
>
>
> I just got back from working a club event at Lime Rock- a little wet
> yesterday, little on the hot side today(in both cases, for workers),
> but as usual a rewarding experience.  Certainly kept busy, save this
> afternoon when I took a ride with an instructor every chance I could
> get(incidentally, thanks to Carter, who gave the fastest ride of the
> set.)
>
> One of the things I help out with is tech'ing cars. It's not exactly
> mind-taxing work, nor do you need strong mechanical skills- you're
> checking over a dozen plus simple things, to basically make sure
> nothing has happened to the car since the student had a pre-tech done
> by a certified mechanic(which is at least 2 dozen lines long, and is
> required- if you don't have it done, you don't run.)  Is anything
> leaking, is the suspension about to fall off, battery bouncing
> around, brake fluid 1+ year old, any caps about to come off, yadda
> yadda.
>
> So the night before, when we open tech for a couple of hours, up
> pulls a TT.  I start going down the checklist, talking with the
> student...and get to the wheels/tires/brakes part.  I explained to
> the student my personal feelings about cross-drilled rotors, and the
> student said something about just wanting to give 'em a try, etc...
>
> Fast forward to today- day #2 of the event.  I'm riding with a
> friend/instructor in his UrQ, and after a few laps, we get a yellow
> at the Uphill station.  Mike comments on what he thinks are chunks of
> rubber on the track- and as we zip by- there's a blue TT sitting off
> on the right in the chicane, with the driver+passenger on the hill
> waiting for the end of the session.  Mike has some trouble with the
> UrQ, so we pack it in a lap or two later, and I resume working the
> pit lane for the rest of the session.  In comes the rungroup, and
> then- at the tail end, very slowly, the TT on the spare tire.
> Thusfar, it looks like he's had a blowout.
>
> Not quite.  The carnage:
>
> -rotor exploded into about at least a half dozen chunks.  All chunks
> had fairly clean breaks centered on the centers of the holes.
>
> -the entire caliper was ripped off the car.  One guide pin mount
> gone, other intact- guide pin probably sheared.  Pads nowhere to be
> found.  Outer bracket, nowhere to be found, only the piston half was
> recovered- and it looked like it had been in a cement mixer with some
> boulders.  Bleeder nipple and brake hose fitting were unrecognizable.
>
> -the rim disintegrated.  There's no better word for what happened.
> Almost the entire inner area was broken into dozens of various sized
> chunks- only the spokes were intact.
>
> -the tire had at least one large puncture in the middle of the tread
>
> -brake line obviously severed
>
> Damage was rather well-contained; the wheel well liner was only
> lightly cut in a few places and there was zero damage to the
> body/paint- with all that metal flying around, kind of amazing.
>
> Thankfully, the failure was on the right front, not left front- if it
> had been the left front, it could have put him head-on into some
> armco.  It would have been a very ugly collision.  Instead, the right
> wheel failure probably pulled him into the turn, and saved his bacon.
>
> Pictures of the carnage:
>
http://frank.mercea.net/~brett/pics/car/rotor_carnage/

Of particular note are the pictures of the left rotor- I saw at least
two cracks, which I took photos of.  They were deep in places, and
extended almost the entire width of the rotor surface.


Brett
--
----
"They that give up essential liberty to obtain temporary
safety deserve neither liberty nor safety." - Ben Franklin
http://www.users.cloud9.net/~brett/