Read these articles first (Below) - some great articles on Brakes and the technology
Technical Support
OE Brake Spec's
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OE Caliper Piston and Master Cylinder Diameters Courtesy of OhondaU
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Si: Fr - 54.00mm
Rr - 33.96mm
MC - 19.05mm
EX/LX: Fr - 53.97mm
Rr - 33.96mm
MC - 19.05mm
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OE Rotor Specs
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Front Si rotor specs
-11.8" Diameter (300 mm)
-24.95mm Thickness new
-23mm Thickness Minimum Worn
-46.7mm Overall thickness (Hat to oposite rotor face)
-27.965mm from hub face to center of rotor
Front Rotor Spec's from "Zaret"
25.61 mm disc thickness
8.49 mm cooling vane width, so there is more internal cooling surface area with the TL rotor
47.49 mm Overall thickness, hat to opposite rotor face
28.45 mm inside hat face (that mates with hub) to rotor (clamping part) centerline
64.21 Hub bore, for a 64.1mm hub
Si / EX Rear Rotor Specs
260mm x 9mm (10.2" x 0.4")
EX's - 10.3"x21mm (F) and 10.2"x0.4" rotors (R)
LX/DX - 10.3" x 21mm(F) rotors and rear drums.
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OE Pad Surface Area
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Si's Front
33.8 Square CM or 5.24 square inches for each pad
EX/LX/DX Front
37.5 Square CM or 5.81 square inches for each pad
EX/Si Rear
40.2" mm x 71.1mm
20.6 Square CM or 8.93 square inches for each pad
LX/DX Drum
57.6 square CM or 8.93 Square inches
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OE Brake Pedal Lever ratio
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OE Si Master Cylinder dimentions
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M/C PIston Diameter 16mm OD, 13mm ID
Piston legth extended - 51MM
81mm O/C bolt spacing
9” vacuum booster.
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OE Service limits
Si Front disk Brake rotor thickness new : 24.9-25.1 mm
Si Front disk Brake rotor thickness max worn : 23mm
LX/DX/EX Front disk Brake rotor thickness new : 20.9-21.1 mm
LX?DX?EX Front disk Brake thickness max worn : 19mm
Si/EX Rear disk Brake rotor thickness new : 8.9-9.1 mm
Si Rear disk Brake rotor thickness max worn :8.0 mm
Rotor Runnout Service limit - 0.04 mm
Rotor Parralleism service limit - 0.015 mm
Si Front Pad New thickness : 9.0-9.7 .1 mm
Si Front pad Service limit thickness : 1.6 mm
EX/LX/DX Front Pad New thickness : 9.6-10.2 mm
EX/LX/DX Front pad Service limit thickness : 1.6 mm
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Performance Brake options for 2006+ Civics
In my quest to find some information on HP Street and Track pads for my New Si, I gathered a fair bit of info that I will share here.
Bare with me ... this is a work in progress as I dig up more info and refine the formatting. If you come across some more information or products, post here and I will update the list.
This information is as accurate as I can make it - but I am depending on web vendors information to be accurate as well.
Do NOT depend on the part-numbers here (Transcription errors will occur), these are here for reference only, please confirm with your dealer before ordering
Further note: I am not listing OE replacement pads -ie pads you can buy at PEP Boys etc ... this is purely OE upgrade or better options.
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Si Coupe Front (2.0) Brake Pads - FMSI# 829
Same as S2000(00-06) RSX-S(02-05)
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Axis / PBR 45-08290U
-Ultimates (Ceramics) - performance street / autoX
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Project Mu
- B-Force - performance streetautoX
- Type NS - performance street
- Titan Kai (HC+) Street / Track / HDPE
- Type N1/777/999 - Track only - various temp ranges
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Akebono
-ACT829 (OE Upgrade)
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Hawk HB-361
-HPS (Street - OE Upgrade)
-Ceramic (Performance Street)
-HP+ (High Performance Street/AutoX)
-Blue (Track/HDPE)
-DTC60 / HT10 / DTC70 (Track, various heat ranges)
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Mintex
-D829MX (Performance - street)
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Stillen
-D829M (OE Upgrade)
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Carbotech CT829
-Bobcat (HP street)
-X6 (Street / Auto-X)
-XP8 (HDPE/Track)
-XP10 (Race)
-XP12 (Race Endurance)
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Cobalt Friction CBR829
-XTR / -XR1 / XR2 /XR3 / XR4 (Race - Various heat ranges)
-XR5 (HDPE/Track)
-GT-Sport(AutoX)
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EBC
-Green - DP2891 (Street)
-Red - DP3891C (Street/track)
-Yellow - DP4891R (Track/HDPE)
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Ferodo
-FDS1444 (perf street)
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Gransport
-GS5 - GS5D829 (Street/track)
-GS6 - GS6D829 (HP Street)
-Pro Ceramic OE Upgrade
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Porterfield AP829
-R4 (Race/HDPE)
-R4E (Race / Endurance)
-R4S (Street/Track)
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LX/DX/EX-Front (1.8L) Brake Pads - FMSI# 465 / 764
Same as 01-05 Coupe EX, 01-3 Hatch, 95-02 Accord Sedan (4cyl)
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Carbotech
-XTR / -XR1 / XR2 /XR3 / XR4 (Race - Various heat ranges)
-XR5 (HDPE/Track)
-GT-Sport(AutoX)
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Porterfield
-R4 (Race/HDPE)
-R4E (Race / Endurance)
-R4S (Street/Track)
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EBC
-Green - DP2812/2 (Street)
-Red - DP3812C (Street/track)
-Yellow - DP4812R (Track/HDPE)
---------------------------------
Grandsport
-GS5 - (Street/track)
-GS6 -(HP Street)
-Pro Ceramic OE Upgrade
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Hawk
-HPS (Performance Street)
-Ceramic (Performance Street)
-HP+ (Street/Track/AutoX)
-Blue (Track/HDPE)
-DTC60 / HT10 / DTC70 (Track, varius heat ranges)
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PBR/AXIS 45-04650U
-Ultimates (Ceramics) - performance street / autoX
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Si / EX Coupe Rear Pads (Disk) - FMSI# 537
Same As EP3(02-05) S2000(02-04) Prelude (92-01) ITR(97-01) TSX(04-05) RSX (04-07)
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Axis / PBR 45-05370U
-Ultimates (Ceramics) -Performance Street - AutoX
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Project Mu
-B-Force - performance street, autoX
-Type NS - performance street
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Akebono
-ACT537 (OE Upgrade)
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Hawk HB-145
-HPS (Performance street)
-Ceramic (Performance street)
-HP+ (Street/Track/AutoX)
-LTS
-Blue (Track/HDPE)
-Black / HT10 (Race - various heat ranges)
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STILLEN
-D537M (OE Upgrade)
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Carbotech - CT537
-Bobcat(HP street)
-AX6 ((HP street / Auto-X)
-XP8 (HDPE)
-XP10 (Race)
-XP12 (Race Endurance)
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Cobalt Friction -CBR537
-XTR / -XR1 / XR2 /XR3 / XR4 (Race - Various heat ranges)
-XR5 (HDPE/Track)
-GT-Sport(High Performance Street AutoX)
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EBC
-Green DP21193 (Street)
-Red-DP31193C (Street/track)
-Yellow- DP41193R (Track/HDPE)
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Gransport
-GS5 - GS5D537 (Street/Track)
-GS6 - GS6D537 (High Performance Street)
-GS3 - GS3D537 (HDPE / Track)
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KVR
-M7418 (OE upgrade)
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Performance Friction
-0537.20 (OE upgrade)
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Porterfield AP537
-R4 (Race/HDPE)
-R4E (Race / Endurance)
-R4S (Street/Track/AutoX)
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LX/DX/ rear Rear Shoes (Drum) - FMSI# 913
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Porterfield Shoe 913 R4/R4S/R4E
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Si Coupe Front Rotor Options (Same as RSX Type-S, 05-06 CRV)
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Stoptech
- Front Slotted
- Front Drilled
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Racing Brake
- Front Slotted i pc
- Front Slotted 2 pc
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Mugen
-Slotted
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PowerSlot
- Cryo-treated and slotted - 912CSL/912CSR
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Brembo - 25831
-OE replacement
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DBA
-1 pcs Front Rotors
-2 Pcs Front Rotors
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LX/DX/EX Front Rotor Options (Same as 02-05 RSX(Base/Prem) / 04-05 Hatch Si )
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EBC -Slotted (Ultimates) - USR7126
EBC -Drilled / Slotted - GD7126
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Racing Brake -Drilled/Slotted
Racing Brake -OE
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Powerslot - Slotted
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Brembo - 25830
OE
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Si/Ex Coupe Rear Rotor Options
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Stoptech
- Rear Slotted
- Rear Drilled
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Mugen
-Slotted
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PowerSlot
- slotted
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Brembo
-OE replacement
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EBC Slotted/Drilled
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Coupe Si / EX with rear disk SS Lines
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-Stoptech
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-Russell
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-Goodridge
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Corsport
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Si Coupe OE Front brake upgrade - 2006 TSX
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Brake options
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Si Coupe Big Brake Kits - For the Extra bit of Performance or Bling - what ever rocks your boat
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FYI - 06 TSX front Calipers and rotors bolt up with only a minor trimming / bending of the dust sheilds. The Rotors are the same diameter, but 3 mm thicker, and the calipers / pads are substatially larger. This provides much better heart dissapation, making this an excellent OE upgrade. Combine these with a good track pads and you have a capable HPDE Lapping / Track combination.
FastBrake -
-12.2" rotor 4 piston (sm caliper) - (Front)
-12.2" rotor 4 piston (lrg caliper) - (Front)
-13" rotor, 4 piston caliper - (Front)
-13" rotor 6 piston caliper - (Front)
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Powerslot Plus
-Larger rotor + stock caliper with relocation bracket (Front)
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Rotora
-13" 1 pc rotor 4-piston caliper (Front)
-13" 2pc rotor, 4-piston caliper (Front)
-14" 2pc rotor, 4-piston caliper (Front)
-Replacement 4-piston Caliper to be used with OE rotor (Front)
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Brembo Grand Sport
-328mm 2 pcs slotted rotor with 4-piston calipers - (Front) 1A2.6022A
-328mm 2 pcs drilled rotor with 4-piston calipers - (Front) 1A1.6022A
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Ksport
13" rotor / 8-piston front
14" rotor / 8-piston front
13" rotor / 6-piston Rear
14" rotor / 6-piston Rear
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LX/DX/EX Big Brake Kits - For the Extra bit of Performance or Bling - what ever rocks your boat
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FastBrakes - various
11" Front
12" Front
13" Front
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Ksport
13" rotor / 8-piston front
14" rotor / 8-piston front
13" rotor / 6-piston Rear
14" rotor / 6-piston Rear
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High Temperature Brake fluid options
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DOT Brake Fluid Minimum Specifications
DOT 3 205°C/401°F(Dry) 140°C/284°F(Wet)
DOT 4 230°C/446°F(Dry) 155°C/311°F(Wet)
DOT 5 260°C/500°F(Dry) 180°C/356°F(Wet)
DOT 5.1 270°C/518°F(Dry) 191°C/375°F(Wet)
An independant comparasin of High Perpormance Brake fluids and what the "Wet" Rating means from one of the Volvo Forums ... a good/short read
Brake Fluid Comparison
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ATE
http://www.ate.de/generator/www/com/.../index_en.html
Super Blue
280C/536F (Dry) 204C/400F (Wet)
Type 200
280C/536F (Dry) 204C/400F (Wet)
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Pentosin
Deutsche Pentosin-Werke GmbH 550cc61
Racing Brake Fluid
300C/572F (Dry) 200C/473F (Wet)
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Motul
Motul
RBF 660
325C/617°F (Dry) 204C/400°F (Wet)
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Motul
Motul
RBF 600
311C/593F (Dry) 215C/411F (Wet)
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Motul
Motul
DOT 5.1
275C/527F (Dry) 185C/365F (Wet)
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Castrol
Castrol Motor Oils and Lubricants
SRF
310C/590F (Dry) 270C/519F (Wet)
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Project Mu
Project Mu Home page
G/Four 335
335C/635F (Dry) 221C/494F (Wet)
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NEO
Home
Super Dot 610
320C/610F (Dry) 210C/410F (Wet)
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Willwood Wilwood Engineering: High Performance Disc Brakes
570 Race
299C/570F (Dry)
EXP 600
330C/626F (Dry) 213C/417F (Wet)
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Ferodo
Ferodo UK - the first name in brakes and friction products
Dot-4
300C/572F (Dry)
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AP Racing Brakes, Calipers, Cylinders, Discs, Pads, Clutches from AP Racing
550 Racing
275C/527F (Dry) 150C/303F (Wet)
600 Racing
300C/572F (Dry) 210C/410F (Wet)
PRF
320C/608F (Dry) 199C/390F (Wet)
----------------------------------------------------
Brembo
Brembo - Brake systems
LCF 600
316C/601F (Dry) 204C/399F (Wet)
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Brake Manufacturers Web-Sites
.:WELCOME TO AXXIS BRAKES:.
Brembo - Brake systems
Carbotech Order
Cobalt Friction Technologies USA
EBC Brakes - Home of the worlds largest range of brake products
FastBrake Enterprises, LLC - Intro
GOODRIDGE GLOBAL | Home
Hawk Performance Brake Pads: Race Proven, Street Legal
KVR Performance Brakes
Performance Friction
Porterfield Racing Brake Pads - Brake Pads for your auto, van and truck. The original Carbon Kevlar Racing Brake Pad. Racing Rotors, Calipers, Fuel Cells, Drum Brakes, Disc Brakes.
POWERSLOT - Faster Stops Made Easier
Project Mu Home page
Rotora: Prodigy of Performance
Russell Performance
Satisfied Performance Brakes
StopTech : Balanced Brake Upgrades
Wilwood Engineering: High Performance Disc Brakes
Performance Brake Parts, Rotors, Calipers, Discs & more! - RacingBrake.com
Ksport USA - Performance Suspension
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Brake technology overview and related thoughts
I have been Auto-Xing and running on the track (HDPE, Solo-1, etc) for a number of years in a couple different Civics (EG/EK), plus I have co-built a couple of Road-race cars. I have done alot of work on brakes, tried numerous setups, as a result I have a fair bit of experience with them ... When you race, you break S**T - when you break S**T you got to fix it ... fixing S**T sucks and cost $$$ ... so you learn real quick what works and what does not.
These are my PERSONAL thoughts on the Following
Drilled and or Slotted rotors.
Not necessary for most street driven cars ... and rarely required for track cars, except at the highest levels. The biggest single problem with MOST slotted / drilled rotors, is that 99% of them started as plain cast rotors, that were drilled / slotted after the fact, and not cast into the rotor. These machined "divots" create potential area's of stress, that can AND will be the starting point for stress cracks, caused by the wide-range heat-cycling of a street driven, or track driven cars.
I cannot count how many times at some track event, I have seen some poor dooffus sitting in the paddock with cracked or worse drilled/slotted rotors - while I am driving home on my plain jane Brembo Blanks which I have beaten the crap out of for hours.
A good thread on the Cross-drilling myths
Cross drilled rotor myths dissolved
You need THREE things for good, consistent, and safe braking.
ONE-A Quality Virgin Metal Cast rotor - IE Brembo Blank. A quality cast rotor, because it has minimal, to no impurities, and because it is cast properly with no micro-voids, will NOT warp or crack under any sort of normal conditions ... however a cheap, off-shore rotor made of god-knows-what scrap metal, can and will warp or worse when heat cycled aggressively
TWO-A quality brake pad MATCHED to the heat range of your intended usage. You need to pick a pad based upon what you intend to do with it. Pads are designed to work within a specific, fairly narrow heat range.
A street pad will warm up quickly to operating temperature, and will grab even when cold, however will fade, quickly stop working at track temps, and will wear out VERY quickly, you can easily go thru a set of OE front pads in 1/2 a day at the track if you are not careful ...driving home with only the backing plates left on the pads sucks !
A higher heat range Track pad, when cold will not stop well, and will eat your rotors. The Same race pad, when used in its recommended heat range, running at optimal temperature, will NOT fade, or eat rotors, and will last a long long time.
THREE-A quality brake fluid, MATCHED to the heat range that you are intending the brakes to be working at. If you are only street driving your car, OE is fine, however if you are doing canyon runs, HDPE, AutoX or live in the mountains, then a brake fluid with a higher heat range is required. For 90% of the users on here, a quality inexpensive dual purpose fluid like Motul RBF or ATE Super Blue is more then sufficient.
Brake Pads.
FACT - ALL brake pads produce dust - PERIOD.
FACT - All high performance brake pads will dust more than OE brake pads ... Deal with it - wash your car more often.
-If they ain't dusting, they ain't working-
Another point - Your brake pads are ONLY AS GOOD AS YOUR TIRES. Your tires are what is actually applying the stopping force (via friction) to the ground ... you could have a $4000 BBK and stop worse than OE if you are running on Michelin XGT's or similar Sh**e tires. You have four VERY small contact points with the ground - make sure those contact patches are good .. upgrade your tires before brakes if you want to stop better.
Brake fade is caused by the pads running outside their heat range, not being able to shed the excess heat, and transferring it to the fluid via the calipers. The pads start to LOOSE grip (like tires will when overheated) - causing you to push harder and longer - transferring even MORE heat to the rotors, calipers and fluid ... and eventually your brake-pedal hits the floor when your brake fluid boils ... normally at the end of a straightaway - This sucks and can get expensive to remove tires or worse from your hood ... been there, done that - bought the T-shirt
Last Point about brake pads ... More aggressive pads do NOT allow you to stop faster or better (Tires do) ... they allow you to CONSISTENTLY stop better when driven aggressively with minimal to no Fade.
Related to the above, a more aggressive pad, IE higher coefficient of friction, will allow you to use less pressure, and brake for a shorter duration of time, to obtain a specific amount of de-acceleration (assuming the de-acceleration rate is within the grip of the tires) ... this means less heat build-up and less potential to fade.
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PERSONAL favorite brake pads.
High performance street / AutoX
-Hawk HP+ Good initial bite, low fade in street conditions, work well, cold ...BUT tend to squeal a bit when cold, and dust a fair bit
-PBR/Axis Ultimates, My new favorite - Cheaper than the Hawks, dust a bit less, do not squeal, and while they do not have the absolute bite, or power of the Hawks, they are close
-Porterfield R4S - Similar to the Hawk HP+ .. good all round performance performance brake pad.
-I tried the Project Mu Titan kAI's (HC+) ...they work fairly well, but are inconsisitant in the grip levels on both the street and track.
PERSONAL favorite pads for Track and HDPE ONLY - these will kill your rotors on the street, make bad noises, and stop worse than OE cold.
Hawk Blues ... Excellent initial Bite, DO NOT fade under normal conditions, wear really well when hot, and when run at optimal temps, are VERY rotor friendly - I could go an entire race season on one set of Blues and one set of Brembo blanks in my EG hatch race beast NOTE: The dust from these is corrosive, and eats into paint when wet - so you have to wash the dust off right away.
Hawk DTC-60/70 ... These pads work very well, are easy to modulate, and take lots of abuse. Plus they dust less than the blues ...BONUS !!!
NOTE: in long trackseeions even these will fade .. highlighting a basic weakness in the OE Brakes heat dissapating characteristics.
****One Key point, For Street use ... if you are upgrading your pads, do fronts and backs at the same time, with same pad material ... this is critical with EBD, because if you have aggressive pads up front, and OE out back, the fronts will grab harder, and EBD will back off the front pressure and add more to the rear to compensate ... so you actually do not gain anything. HOWEVER with the same pad front and back, both will grab equally and the car's EBD will not have to compensate, and the more aggressive pads will stop you properly. This is the same reason why most (front only) BBK's do not work well ... to much brake up front = more braking power dialed to the back brakes by the EBD system.
For Track Use ... a more aggressive front pad with a higher temp range is preferable (with our cars) due to the front heavy nature of these cars. You will not get enough heat into a full race pad in the rear. Something along the lines of a Hawk DTC-60 upfront and HP+ out back should work well. This allows you to run HP+ all arround on the street,and swap out only the fronts to DTC-60 (and matched rotors) or similar compound when you are at the track.
Oh Yeah - I keep remembering new points - The KEY to proper performance and life of a NEW rotor / pad setup is the break-in process. Aggressive pads MUST be properly bedded in to get a consistent transfer layer onto the rotors ... without the proper initial bed-in process you will never get consistent braking performance. In reality ALLOT of the "warped" rotor problems are not from a warped rotor, but from a inconsistent transfer layer or pad material on the rotor (which causes shake under braking), caused by improper/no initial bedding
One Final point - these cars (8th Gen Si's) have excellent brakes from the factory ... the 11.8" fronts and 10.2" rears have more than enough swept area and heat dissipation characteristics for anything but full on track requirements.
Tracking your Si (HDPE / lapping etc)
IF you are tracking your car regularily then the limitations of your OE front brakes will become apparent ... they just do NOT have enough thermal mass to dissapate teh heat generated by long track sessions ... the pads overheat and fade. The easiest / cheapest up grade is to sweap on an set of 04-08 TSX front rotors and pads, combined with a set of dedicated "race" pads such as the Hawk DTC-60 or similar.
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OK, Lets talk about BBK's (Big Brake Kits) ...the Good points
As I mentioned above, they are overkill for pretty much all street applications, however they do have their applications.
The Si's come with 11.8(F) and 10.2(R), rotors the EX's with 10.3"(f) and 10.2" rotors rear, and the rest come with 10.8"(f) rotors and rear drums. These rotor / pad combinations have more than enough ability to lock up the tires and cause the ABS to come on ... what is a BBK going to do? ....allow you to lock up the tires for longer ...make the ABS chatter longer? .... In a nutshell YES ...
The limiting factor in ANY MODERN braking system is not the brake components, it is the Grip/Traction/Friction provided by the tires. If you want to stop faster / shorter ... put wider / sticker tires on the car. Tires will ALWAYS be the limiting factor in absolute braking performance.
OK ... so what does a BBK or a similar OE brake upgrade offer?
Basically it allows for more CONSISTENT braking when you are using the braking system (Pads/Rotors/Calipers) in an extreme situation, where they are operating at or near maximum temperature. The only place thus really shows up is in two area's ... on the Track and in the Mountains(doing canyon runs etc)
So what is happening in these situations that "stress" a OE setup? Well you are doing a coupe of things ....
-Applying the brakes for a longer duration (higher speed = longer braking distances)
-You are applying them harder (You are trying to stop in the shortest distance possible within the grip of the tires)
-You are using them more often within a short period of time (multiple corners you are having to brake for in short duration, MANY MANY TIMES) with out much opportunity to cool down
This is a situation you do not see on the street ... at least not consistently. .
OK ... so what does the three effects (above) for track/canyon specific driving do to your brakes ... One word ... HEAT, LOTS OF HEAT. Brakes work by squeezing the moving rotor between two abrasive pads. These pads use friction to slow down the rotation of the rotor. This friction creates heat ... there is nothing you can do about this ..it is physics
You can deal with this heat in a number of ways.
1-Use appropriate brake pads that have a heat range that matches the application
2-Use a Brake fluid that has enough temperature range to match the heat range that you subjecting the brakes to.
3-A quality Rotor that can shed this heat effectively without warping or cracking
4-Put some sort of ducting in place to help cool the rotors/pads.
THIS is why by simply upgrading your pads, changing your fluid, and using quality cast rotors is all you will ever require for street and mild track use ...
OK ... we still have not talked about what a BBK/Upgrade provides above and beyond making sure the above is taken care of .. so lets look at What BBK's provide
BBK's have the following advantages over OE ...
Rotors:
Larger / thicker rotors have more surface area to help shed heat ...ie they are a bigger "radiator" allowing heat to more efficiently be removed by the cooling effect of the surrounding air. (Remember brakes are air-cooled devices)
Larger / thicker rotors have more thermal "mass" allowing them to resist sudden changes in temperature (which is a both good and bad thing) Thus as you heat cycle them aggressively they will have less tendency to deform and warp
A "good" BBK kit will have 2pc rotors. A Cast iron donut shaped outer ring (which the brake pads press against) , bolted to a aluminum center hat(which attach's the rotor to the hub). This type of rotor assembly is lighter than a full cast rotor, but more importantly it allows the rotor to "float" or expand and contract without warping or twisting against the center cap, thus not distorting under hard braking. What this does is allows more consistent braking pressure to be applied to the rotor.
Calipers:
A "good" BBK kit uses a Mono block Aluminum caliper, with 4 or more pistons. So why is this important?. Well most OE Calipers use a cast caliper that floats or slides on a couple of pins (sliders). As you apply the brakes, the brake fluid, pushes a single piston out against the inner brake pad, which causes the entire caliper to slide and center itself around the rotor, and eventually be "squeezed" between the inner and outer pads, slowing the rotor down. Because the caliper floats, it can and will move around under hard braking due to the extreme amounts of force involved.
Secondly, when you only have one piston pushing in the middle of a pad, on one side, the pad will warp a bit, even with the thick backing plate, not allowing full and even pressure across the entire pad surface, thus not full and even friction, thus less braking.
The third thing that happens under hard braking, is that as you push the the pad against a FAST spinning rotor, it is pushed back a bit AND the trailing edge of the pad "floats" a bit, putting more pressure on the front of the pad with less on th rear, thus reducing the overall friction a bit.
So a Floating OE style caliper will NOT provide AS consistant and even pad pressure as a Mono block when USED HARD. A Mono block Caliper is a solid chunk of machined aluminum that is rigidly bolted to the knuckle. Multiple pistons apply pressure to BOTH pads, equally squeezing the rotor between them. So there is minimal deflection of the pad and caliper under HARD braking and you get more even pad pressure. Even more cool is when you increase the number of pistons, you spread the pressure across more of the pad thus allowing for more even and CONSISTENT pad pressure. The final cool part about mono block calipers is that you can stagger the size of the pistons and the internal orifices that feed the brake fluid to the pistons, you can VARY the pressure that is applied across the pad, to compensate for the drift or twisting of the pad caused by the spinning rotor deflecting the pads, you can even out and maximize the pad pressure.
So at the end of the day a properly designed BBK will provide MORE CONSTANT Braking when the brakes are used at the limit ... however it will still not necessarily provide shorter stopping distances.
BBK's come at a cost ... Big Dollars (You can redo you Brakes with OE upgrade stuff for 1/5th the cost of a BBK kit) ... more unsprung weight (Big brakes are heavier -unless you go Carbon Carbon) , more rotational inertia to overcome (The larger mass of the rotor is harder to spin, thus eating up HP) ...and finally and probably most importantly they can and probably will throw off the Front-Rear Bias of the brake system, actually hurting the braking performance.
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OK, Lets talk about BBK's (Big Brake Kits) ...the Bad points
Cost:
They are expensive, particularly for the "good ones" - you can install have a good set of street pads, a spare set or track pads and rotors plus a quality brake fluid for 1/4 or better the cost of a BBK
Unsprung weight:
When you are taking about big chunks of cast iron (rotors) and big calipers (Iron or Aluminum) - size matters ...big brakes are heavy, and this additional weight is the WORST type of weight, unsprung weight. This weight is acting directly on the suspension, and it has a far larger effect on traction, ride quality,and handling then weight that is "sprung" or supported by the springs. Basically this additional weight = additional inertia has to be overcome by the suspension. There is a really good description of unsprung weight right here ...Unsprung weight - Wikipedia, the free encyclopedia
Basically This additional weight hinders the ability of the cars suspension to follow the road surface when it is uneven ... you loose traction earlier.
Big brakes have more rotational inertia to overcome:
A bigger/thicker/taller rotor has more rotational inertia to overcome.
-The larger mass of the rotor is harder to spin, thus requiring more HP to overcome this mass.
-A Taller rotor moves the mass further away from the center point of the rotation, thus making it harder to spin, and requiring more HP to overcome this There is a really good description of rotational inertia and its effects here .... Moment of inertia - Wikipedia, the free encyclopedia
Case in point. On my prior race car (93 Si Hatch) I "Upgraded" from the stock 9.5" front rotors to 11" (Poor mans ITR) as the OE 9.5" were fading even with the proper pads and fluid .. I needed more thermal mass to shed the heat building up after multiple hot laps. This upgrade worked well except for one thing ...when I dynoed the car after the brake upgrade I lost close to 10 HP ... because a had taller heavier rotors and I had to stop running my 13" rims and started running taller and heavier `15" rims. All this additional rational initial "Consumed" more HP
Reliability over time:
OE brakes are DESIGNED to be very reliable over a long prior of time, requiring little maintenance, other than lubricating the sliders and replacing the fluids. One of the weak area's or many BBK's is that the calipers are designed mostly for race applications where they do not see the long life, salt, or corrosion that most daily driven cars do. In many cases True Race Calipers have little or no dust seals to protect the pistons. These Calipers may only last one winter before the internal components are pitted and permanently damaged. To be fair ... the aftermarket suppliers have got much better over the past few years and the caliper and seal design has improved allot, HOWEVER I wonder how long a nice set of "Insert BBK name here" will last two Michigan or Quebec Winters ?
So ...Botom line, BBK's require regular maintenance and inspections ...particularily when used in harsh environments.
Front to Rear Brake Bias and fluid pressure:
Finally and probably most importantly a BBK can and probably will throw off the Front to Rear Bias of the brake system, actually hurting the braking performance. The OE brakes are DESIGNED to use a specific amount or fluid pressure to exert a specific amount of pad pressure, with a specific front to rear pressure differential. When you add an aftermarket front brake package ... these big multi-piston calipers use a different fluid volume and pressure than OE to exert a specific pad pressure. This will cause the front brakes to either apply more or Less pressure then what the car was designed for ... thus you will either have to much front or rear brakes applied. This may cause at least, poor braking performance, and at worst a dangerous situation where this front to rear mismatch can cause your car to spin, or loose control. EBD or Electronic Brake distribution can manage small variations in front to rear pressure, but not the extremes that might be caused my a poorly designed BBK. Related to this, is the OE ABS system is calibrated to the OE brakes characteristics, a large change the characteristics can mess up the system, reducing performance as this could cause the ABS to kick in to early or late.
Here is a second opinion ...a Professional opinion and test of BBK's
Shedding Light on Fading Brakes - Features - Car and Driver September 2002
Final Word ... You are optimizing an already good setup. This sort of purchase is to find that last 5-10% of performance in the braking system.
There you go ... it is up to you to make an educated decision of what direction is best for you ... and is the additional cost of a BBK worth it for your needs.
