[s-cars] The front brake upgrade grinds forward

Theodore Chen tedebearp at yahoo.com
Sat Mar 25 04:03:58 EST 2006


they have patent applications on those rotor designs.  when i saw
the application serial numbers, i suspected that they might have
been published because those serial numbers are from a couple of years
back.  sure enough, i found them on the US patent office's website; e.g.
http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1&f=G&l=50&co1=AND&d=PG01&s1=10%2F861213&OS=10/861213&RS=10/861213

of course, just because they have applications doesn't mean patents
will be granted, and just because they're patented doesn't mean they're
any good.

i think the jury is out on those rotors.  they have a lot of claims on
their website, but i'd want to see actual test data showing that the rotors
are running cooler, warping less, etc.  i can tell you right now that i
think the open slot design is a very bad idea, because it severely weakens
the rotor.  you have to beef up the structure to make up for the open slots.

remember that the rotors are under tremendous mechanical and thermal
stress - compressive stress from the calipers clamping the rotors,
friction loading from the pads against the rotors, and centrifugal (OK,
centripetal) forces from spinning the rotors.  cutting a large slot
all the way through the surface is even worse than drilling little holes
in it.  cutting the slots removes material, increasing stress concentrations,
and imperfections in the process creates stress risers right where you
just concentrated stress.  i'm getting deja vu - i must have ranted about
this before:

http://www.audifans.com/pipermail/s-car-list/2005-May/040967.html

but this is worse than cross-drilling, because the holes are so large.
you're just asking for catastrophic rotor failure.  to make up for the
open slots, you'd have to do a lot of work to reinforce the structure
and add more metal to it.

the jury is out on whether these rotors actually cool better, but i'd
also ask how it might affect the strength of the rotor.  the vanes on
normal vented rotors are part of the structure of the rotor.  by changing
the arrangement and configuration of the vanes, they've likely compromised
the strength of the rotor, and that's why they added the stiffening ribs
that they're claiming as a feature.

i'm not saying that these rotors are no good, but i would need to have
them prove to me that these rotors work better and are strong enough to
withstand the rigors of track use.  i suspect they're not going to be
good for more than bling on the street, at least not judging by the 
pictures.  look at those open slots running almost the entire width of
the friction surface.  that scares the crap out of me.  as for the
testimonials, if you read in the forum you'll see the people giving
testimonials are sponsored by the company.

of all the features they cite, the center mount seems like the most viable,
but i also have to wonder about how it might affect the strength of the
mounting tabs.  the center mount design means all of the tabs have two
bends in them, and a bend is a potential failure point.  this problem can
likely be fixed by adding enough metal to the tabs.

i'd wait for audi to put these things on the R10.  in the meantime, i'll
stick with brembo and wilwood rotors for my race car.  i don't like to
be first on the block when it comes to mission-critical parts.  nobody's
paying for my parts and car, and i'm not getting any money out of it.

well, you asked.

-teddy

--- mlp on D530 <mlped at qwest.net> wrote:

> Teddy, just curious if you or Taka have any thoughts or opinions on
> RacingBrake's two piece rotor/hat design?
> 
> 	http://www.racingbrake.com/main/technology.asp 
> 
> They seem to have a pretty unique hat mounting system and slotting design
> for which they make a lot of claims. 
> 
> >-----Original Message-----
> >From: s-car-list On Behalf Of Theodore Chen
> 
> >--- Taka Mizutani <t44tqtro at gmail.com> wrote:
> >
> >> Evan-
> >> Thanks.
> >> 
> >> I meant, what are the advantages of a floating 2-piece rotor 
> >versus a fixed 2-piece rotor? 
> ....
> 
> >the advantage of a floating rotor is mostly theoretical. .....
> >
> >> As for brake ducting, yes, it does matter to me.   ..... 
> >
> >brake ducting can only help, and it's relatively cheap.  
> >
> >> As for track use, I faded the Porsche 996 caliper / MBZ 
> >320x30mm rotor 
> 
> FWLIW, I concur.  If you're planning on doing track, the extra 2mm in the
> 322x32mm Porsche 993tt rotors is well worth the extra costs of those setups.
> This is a case of Pound (as in English �) wise, penny, �, foolish IMO.
> 
> Cheers
> Mike 
> 
> 
> 


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