[s-cars] Front brake research continues...

[Greg Johnson]

Greetings!

It's the west coast Greg of BIRA.   I hope I've remembered all the
questions.

 In short, the dimensions of bracket designs are dictated by the rotors.
Where we had the need for lots of material, we used a hunk of anodized
aircraft grade aluminum with steel inserts.  Where we had to go narrow, (e.g.
Sys 6 for the A8 and the UFO Sys) we used steel.  Weight and strength were
additional considerations.

For urS4 and urS6 cars there was Sys1, which used the Boxster Monobloc over
the 312x25mm A8 Rotor.  The learned "problem" with Sys1 was that the rotor
"hat" is narrow and it put the monobloc too close the wheel "spokes."
Without spacers, it did not fit as many wheels as we had hoped.  This led us
to Sys3 which places the Boxster S/996 Monobloc over the EuroA8 314x30mm
rotor.  The multiple advantages to Sys3 have obsoleted Sys1.  First, the
rotor "hat" is wider, so it moved everything away from the wheel spokes and
as a result, it fits more 16in wheels.  In fact, I cannot remember anyone
having to run spacers with Sys3 but someone may correct me.  Second, the
Boxster S/996 Monobloc caliper is a bit bigger than the Boxster monobloc so
one gets more brake.  Third, the rotor is slightly taller ,which provides a
better mechanical advantage and it's 5mm wider which means it breathes
better and runs a bit cooler.  Rotors are heat sinks and the more rotor one
has have the more heat it can absorb.   For the street and general track
use, Sys3 is the ticket.  I ran slotted rotors and used the sound dampeners
and brake goop (CRC?) since day one and the pads never squealed.   The track
pads, without the goop or dampeners squeal like a pig until they warm up.
So much so my instructor said - "what is that noise?  Which eventually led
to "jeez, what kind of brakes are on this car?"  Sys3 performs well on the
track.  Really, it's as much as most folks ever need for the street or the
track.  If one is patient, one can find used Boxster S/996 monoblocs on the
'Net.  I bought mine used for $300 but that was a few years ago.

BIRA Sys6 was designed by GregA and a certain unnamed crazed Audi driver
from Colorado.  GregA drives race cars and the CL Audi driver may as well
drive race cars.  They wanted a track braking system.  Sys6 puts the 996TT
monobloc over the GT3 rotor.  It's expensive because it requires rotor hats
and caliper brackets and depending on quantity and what the machine shop is
quoting, all of that costs about $650.   I'm currently running Sys6 on my
urS4 with stock pads and they do not squeal.  I've not been the track yet
but will do this summer.  Given what Sys3 does on the track with track pads,
I'm really looking foward to Sys6.  A pleasant surprise was that Sys6 just
does fit under the stock 16in urS4 5 spoke wheels  If I had to travel gravel
roads I would probably avoid this combination.  I use the 5 spokes in the
winter and run 17 in OZ superlegs in the summer.  I recommend these wheels.
Pictures of Sys3 and Sys6 can be seen on our website.

Sys6 was designed so that when it came time to rebuild a 993 split caliper,
one would have the option of upgrading to the 996tt monobloc and one could
use the existing hats and rotors. This led to the discovery that our Sys6
hats also allow persons to use the RS2 brackets with a 993 caliper, over an
Audi S8? rotor.  We did not create this design and don't support it but we
do provide Sys6 hats for those BIRA members who want to go this route.
Again, depending on quantity and what the machine shop is quoting, the hats
usually cost about $450.

As to the differences between split, bolt-through 993 and monobloc, our
stiffness and weight claims are based purely upon what Porsche/Brembo have
stated.  From a practical perspective, when we were creating BIRA brakes,
the monoblocs had just come out and Porsche said they were lighter and
stiffer, so why design for Porsche's old tech when the new tech was
available?

We currently have a limited quantity of Sys 6 parts (hats and brackets) in
stock.  Anything else would have to be built.  If folks want brakes for the
spring, now is the time to get the ball rolling, because the lead time is
based upon herding all of the cats and then getting the machine shop going.
Unfortunately, the law of supply and demand is alive and well at machine
shops.  They love $100K contracts; thus $5K contracts get done during the
slow times.  We have found a new machine shop, but the game hasn't changed
much and there's not a whole lot we can do about it.

HTH,

Greg J
BIRA.ORG