Re: Cross-drill = cracked rotors?

["Pat Martin" <mardkins@email.msn.com>]

Luckily I have some real world data to discuss this issue.  On my 4kqt I
have had the (stock size) cross drilled ATE rotors on with Porterfeild R
compounds.  I switched to the R compounds from slagmasters and drove these
particular rotors for ~35000 miles and probably 15 track days.   The Ate
rotors were even cross drilled improperly so they tended to groove very
quickly.  It was only after turning them down to the minimum spec and
running another 10000 miles that they finally cracked.

I just bought some Brembo cross drilled rotors and still running the r
compound pads and Sean Upchurch just bought (stock size) slotted rotors with
the same pads in his 4kqt.  We just did a track day and I had the
opportunity to drive his car for a few laps.  Neither car had any fade, even
after several hard 115-40 slowdowns in a row. But his car's brakes requires
much more effort than mine did to make that stop.  They had similar power
but it still feels like mine stopped harder.  He felt the same way.

Not the same as street driving but for what it is worth the peddle feel is
better with the drilled rotors on the track and the street.  As far as non
drilled rotors stopping the same as drilled that is NOT the case. BTDT

I will agree the pads make the biggest difference.

Pat Martin
86 4000csq turbo, 2 1/2 cat back, H&R-Boge, MC and loving it.  Drilled and
stopping it. Koenig Cobra 16x7 with Yokohama A520's turning it,  K&N and
uh.. Chromeless
84 4000sq  AKA: The beater.  Which still has very faded chrome
95 subaru legacy
Bothell, Wa


 >I got some nice brembo rotors and when installing them, my mech. said
> >that
> >they will crack.  "Its not IF they will crack, its WHEN it will
> >crack?"  This
> >kinda scared me a bit.  Q-list confirm this?
>
> Not with a BTDT, but have heard the same stories.  I currently have
x-drilled Brembo rotors,
> and must say I noticed zero performance difference from stock.  I expected
to see much
> less fading, that did not happen.  OTOH, switching different pads has made
a much greater
> difference.  Stock -> Rofren = no difference.  Rofren -> Westons (AFT/ -3
compound)
> = amazing difference.
> Next set of rotors will be stock undrilled.  We'll see if that is a step
backwards now that
> I've found some pads that rock.  Even if that happens I doubt I will go
with x-drilleds
> again, given the anecdotal stories of cracking.  Slotted rotors may be a
better alternative,
> but I think that this may also have some cracking exposure, as it is also
a machining process
> done to the rotors which inherently disturbs the metalurgy.
> And I can confirm the other comments about improved feel and response with
SS lines.
> But there are also horror stories about these failing, so I intend to
replace mine every 2
> years.
>
> Matt Rooke
> '91cq
>
>
>