[Es2] 996 caliper weight?

[Miller, Chris]

See below. The Carrera brakes are a bit larger than the Boxster brakes
that were weighed, but you get the gist.
Chris

>From Eric Fluhr's post to the Quattro List, 06/06/00

Ok, I finally finished upgrading to the BIRA System 1 on my Urquattro,
replacing the G60 brakes I had installed last year (and toasted at
several track events since then). Hopefully this will be a reasonably
objective comparison of the BIRA versus the G60 brakes on my car.

First, an overview of the different Urq brake systems and my concerns.
Back in early 1999, I replaced the factory 54mm single-piston brakes and
280mm rotors with set of G60 dual-piston calipers (affectionately called
"Boat Anchors") and 276mm Ate Powerdisc rotors with KVR Carbon Fibre
brake pads. With those "new" brakes, I noticed an increase in pedal
travel needed to stop the car, but the brakes grabbed well once hot. On
the track the G60 system worked nicely, but after 3 events the pad
surface had disintegrated (chunked?). So, I begin investigating other
bigger brake kits, and decided to try the BIRA System 1. This kit uses
314mmx25mm factory rotors from the U.S. Audi A8 and the [smaller than
Big Red] 4-piston caliper from the Porsche Boxster.

I had several concerns about this kit, when I decided to use it:

How heavy it is compared to a true big-brake kit?
The rotor is only 25mm versus 30-32mm for a big-brake kit, which means
less mass and smaller vents for cooling. Would the rotor warp from
overheating?
Would it fit under my 16" wheels?
What would happen to pedal travel and pedal feel?
How will braking be affected?
To answer question (1), I took the BIRA kit, my G60 brakes, and a set of
A4 brakes (which will fit a G60 car) to my local Post Office at midnight
in true Jeff-Goggin-School-Of-Measurements fashion. :-) I list the
results in the table below. Please note that the A4 brakes were severely
worn (the owner replaced them with Big Brembos), the G60 brakes were
slightly worn, and the BIRA kit was brand new. Also, the BIRA caliper
was weighed with the bracket, since the bracket is effectively its
carrier.

 1 Rotor         1 Caliper, 1 Carrier and pads               Total for
one side
------------------------------------------------------------------------
---------------------------
G60, 276mm rotor, dual-piston caliper 

15lbs 1oz              14lbs 14.4oz
29lbs 15.4oz
A4, 288mm rotor, 57mm single-piston caliper 

15lbs 12.8oz          12lbs 10.2oz
28lbs 7oz
BIRA, 314mm rotor, 4-piston monobloc Boxster caliper 

18lbs 15oz              8lbs 12.0oz
27lbs 11oz

Not surprisingly, the A8 rotor weighs 3-4lbs more than the other brake
rotors. The extremely light Porsche caliper helps make up for it,
though. Overall, I drop 2lbs per side by going with the BIRA kit,
however more of the brake mass is rotating mass. In comparison, a true
big-brake kit with two-piece rotors and aluminum hats would probably
lose ~8-10lbs per side, and the rotating mass would be part of that
reduction. So, one of the trade-offs of the BIRA kit is a smaller
reduction of unsprung weight than a true big-brake kit would afford.
Since I am still losing weight overall while gaining a significant
increase in braking power, I am satisfied with this cost-performance
trade-off.


-----Original Message-----
From: es2-bounces at audifans.com [mailto:es2-bounces at audifans.com] On
Behalf Of Ben Klumper
Sent: Tuesday, April 12, 2005 3:48 PM
To: eS2 List
Subject: [Es2] 996 caliper weight?

Anyone know how much a 996 (non turbo) front caliper weighs, vs the
stock G60 caliper?

Ben
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