Brake Rotors, Pads, Lines, Fluids, and Ducts – Oh my!
By MG (Smike).
Everything you wanted to know about brakes and upgrading them for street, autocross, and track specifications.
This thread will cover:
—-Slotted, Drilled, Dimpled, Blank
—-1-piece v. 2-piece
—-Material and Treatment
—-Pad Material Transfer (aka “Warping”)
–Brake Pads (when/why/tires)
—- Street Pads
—- Track Pads
—- Street Tire
–Brake Duct Cooling Kits
Slotted, Drilled, Dimpled, Blank.
Rotors have slotted CNC machined into the rotor’s face. Dimpled have, well, dimples – just like a golfball.
Pros: This helps with de-gassing that brake pads under hard use and high speeds. A thin layer of gas can form that can interfere with pad contact to the rotor. The idea here is the vein/slot/dimple will give an exit for the gas to escape/go.
Cons: If you ever have pad material transfer (warping) on the rotor face you will not be able to mill the rotor surface (take off a thin amount of material to clear up pad transfer)*. Creates fissure points for the rotor to crack from. De-gassing is not often heard of anymore. And doing 200 mph to zero runs — not common.
*True for about 95% of the world. Some higher end shops (race shops) will be able to mill slotted rotors. Check area for availably.
Recommendations: street use, autocross use, track use**.
**Note: pad transfer can occur, not turning means wobbly braking. Use at your own discretion.
Two variations – holes are a part of the rotors mold and holes where drilled into the rotor after it was molded. Typically, the molded with holes is more expensive, but it is better than having the rotors drilled after molding.
Pros: Supposedly helps with rotor cooling. However, today’s, modern rotors, have internal venting vanes in between the rotor faces.
Cons: Rotors that are drilled after being molded can be weakened, structurally. Many HPDE event organizers will not allow cars with such rotors on the track.
Recommendations: street use and autocross use.
Just like the OE rotors. No modifications to the rotor face.
Pros: Lots of contact in terms of rotor face to pad.
Cons: If you think you are gassing the pads – no where for gasses to go.
Recommendations: street use, autocross use, track use.
1-piece: Rotors/hat are molded as one complete piece.
2-piece: Rotors and hats are two separate pieces.
1-piece v. 2-piece:
2-piece rotors do a better job of heat transferring, specifically, not transferring the heat back into the hat. They do carry a higher upfront cost over 1-piece rotors, but the benefit is that when a new rotor face is called for, you just have to change the rotor ring and not the whole assembly. 2-piece are also lighter by 3-4lbs thanks to hat material used. They also can expand and contract without interfering with the hat.
1-piece Pros: Cheaper, work well. Cons: Heat transferring at the limit.
2-piece Pros: Heat transferring control, weight savings. Cons: Costs.
There are a few variations on the internal vane construction – straight, curved, island. Straight vane are generally the standard. Cheap and non-directional. Curved vanes are directional and must be installed correctly for them to be effective. Island (DBA) is a mixture between straight and curved. Islands are mini-vanes that direct air like a pinball machine.
Material and Treatment
Stay away from low end rotors. Metal used is less pure and typically not as durable. Another option is cryogenic treatment. Similar to forging steel. Cryogenic treatments (PowerSlot) adjust the internal molecular structure of the rotor material to relieve the internal residual processing stresses from manufacturing. Result is often a rotor that wears better and longer. Resistant to pad material transfer (“warping”).
Pad Material Transfer (Warping)
Brake jitter, which may people commonly call “warping”, is not true warping. It is pad material transfer from the pad surface to the rotor surface. Creating a high/low environment on the rotor surface. That high/low is the jitter that is transferred back to your brake pedal and steering wheel. Pad material transfer happens when the pad got too hot or pad type used is too far outside of its operating range. When a pad is beyond its maximum operating temperature (MOT) it will start to breakdown. Not only will this significantly decrease the pad material, but it can lead to catastrophic failures (pad separating from backing plate). Inversely, when a pad is used below its operating range (like many race pads), can lay an uneven layer of material film on the rotor.
FRONT ROTOR WEIGHT (each, lbs)
REAR ROTOR WEIGHT (each, lbs)
Two sections here – street and track. I am a big proponent to separating the two. Brakes are the line between you on the track and you flying off the track at the end of a straightaway. On the tracks, massive amounts of heat is generated. Street pads are just not designed to handle those levels of heat.
These are pads that are only meant to be run on the street or in autocross events. Again, they should never be taken out on the track. Their drag coefficients fall off quickly when past their operating temperature.
Acceptable street only pads:
Satisfied GranSport GS: 100-700F, .42 drag coefficient
Ferodo DS2500: 100-1000F, .50 drag coefficient
Porterfield R4-S: 0-1000F (0-600F optimal), .4 drag coefficient
Performance Friction OEM
Hawk HPS: 0-600F, low/no bite (glazed over on my street setup) PIC HERE
Hawk HP+: 0-700F, better bite can be noisy on street good for autocrossing
EBC RedStuff: 200-1400F, .50 drag coefficient
CL RC5+: 0-1300F, 0.4 drag coefficient
CL RC6E: 0-1800F, 0.46 drag coefficient
These are pads that are only meant to be run on the track. Again, they should not be taken out on the street.* They take some temperature to work right, without that temperature they might not work or have much stopping bite. *Some pads are now blending those lines. Enough cold bite to work on the street. Might make noise or wear rotors faster.
Two levels to track pads – street tires and r-comp/slicked type tires. Generally, stickier tires (r-comps) means you will need more brake due to the increased levels of grip the tires will give you. They can and will overpower your pads. Also, more power equals more speed means the same ruling as r-comps.
How much power or weight? On a previous car, 3200 lbs with 340whp, trapped 116-117 in the quarter mile. I was at the edge of street tire type pads (HT10). If you make over 350whp or weigh in at over 3200 lbs – a beefer pad might be wise.
Acceptable track only pads – Street tires
Hawk HT10: 300-1300F, intermediate to high torque
Hawk HT14: 300-1400F, high torque
Porterfield R4: 100-1200F (100-900F optimal), .52 drag coefficient
Racing Brake ET700: 100-1200F, intermediate torque
Racing Brake ET800: 100-1400F, intermediate to high torque
Performance Friction 97’s: 167-2000F, intermediate to high torque
EBC YellowStuff: 300-1750F, intermediate to high torque
CL RC5+: 0-1300F, 0.4 drag coefficient
CL RC6E: 0-1800F, 0.46 drag coefficient
Acceptable track only pads – R-comp tires or high hp or heavy car
Hawk DTC60: 400-1600F, high torque
Hawk DTC70: 400-1600F, higher torque than 60’s
Racing Brake ET900: 300-1600F, high torque
Performance Friction 01: 167-2000F, high torque
Carbotech XP12: 250 to 2000F, high torque
Raybestos ST43: ? to 1400F, high torque
EBC BlueStuff: 300-1750F, high torque
CL RC6: 0-1800F, 0.5 drag coefficient (intermediate to high torque)
CL RC8: 0-1800F, 0.6 drag coefficient (high torque)
Bedding Pads and Rotors
Most quality pads have been burnished in the factory. Subjected to a heat cycle and cool down. This molecularly fortifies the pad material for application use. A final bedding once on car will finish the installation process. Another heat cycle and transfer a thin working layer of material to the rotor surface.
If installing new rotors with current pads. Bed as below to apply thin working layer of material to the new rotor surface. *With new rotors be sure to clean with soap and water to remove oil on metal. Oil is there to keep them from rusting from factory to you.
I use this bedding process:
-Install pads. Clean rotor surface with brake cleaner very thoroughly
-Daily drive for 3-4 days
-Do 6 to 10 60-10 moderate pedal stops (might smell brake pad)
-Drive back to house trying my best to not use brakes
-Park car for a few hours to let cool off
*Noise: If you do the above and get a squeal or noise. Apply CRC Industries Disc Brake Quiet (orange glue type material) to backing plate where it touches the caliper piston and/or fork. Let dry. Install and drive. Noises come from a few places. One is pad lightly touching the rotor causing a squeal transmitted through the pad into the caliper.
Pad Reviews and Comparisons
Stainless Steel (SS) Braided Lines
These are brake lines that directly replace your original rubber/steel reinforced lines. The benefit here is not immediate, but consistency. In the past, OE rubber lines have been known to expand, leading to a squishy pedal, or worse, crack, leading to death. Most modern cars seem to have decent lines, less cracking events (bad for manufactures). But, hot lap after hot lap, the lines can start to get a heat transferred into them. The SS lines will not expand, this is where the consistency in pedal feel comes from. And now can be had for a reasonable cost.
Not all SS lines are created equal. SS lines must be DOT approved.
A must for any autocross or track car, and not a bad idea at all for a street car. DOT4 resists boiling over in extreme usage (racing). Higher the dry/wet temperatures the better, but cost is a factor here, some can be very expensive.
Fluids should be flushed at least every 2 years on a street only car. Brake fluid is hydrophilic – it literally loves water. Water becomes suspended within the fluid and lowers the temperature ranges.
For track or autocross cars, the fluid should be changed/bled much more often. Running the fluids at high temperatures does wear it out over time. This can be seen in its color. Most fluids are a clearish color, after track or heavy autocross use they will go to amber and even black.
As a reference, I flush the fluids every spring to 100% fresh. Then bleed before any track days and every couple of autocross events. 12 oz will do a bleeding, 24 oz for a flush, 36 oz for brakes and clutch lines. Power bleeders like the Motive units make it a very easy job.
DOT4 Fluid Ratings: Dry // Wet
Amsoil Series 600 DOT 4 (BF4) 580 // 410
Prestone HP DOT4 500 // 311
Castrol SRF 590 // 518
Neo Super DOT 610 610 // 421
Motul Racing 600 585 // 421
Motul Racing 660 610 // 400
ATE Super Blue Racing 536 // 392
ATE TYP 200 536 // 392
Valvoline Synpower 480 // 311
Castrol LMA DOT 3/4 446 // 311
Ford Heavy Duty DOT 3 550 // 290
Performance Friction 550 // 284
Brembo Sport 500 520 // 336
Endless RF650 622 // 424
Fuch’s Silkolene Pro-Race 2000 572 // 383
Chemistry Note: Look for something that contains boric acid or says it contains borates. These fluids will last longer because they keep the water from actually affecting the boiling point. These fluids scavenge water because they contain esters of boric acid. When water gets into the fluid, it hydrolyzes the ester into a long chain alcohol (normal brake fluid) and a boric acid unit (still has high boiling point). This will extend the life of the fluid in terms of water absorption.
Brake Duct Cooling Kits
Brake duct cooling kits do exactly what they sound like – they cool the brake rotors with direct cool air. These are very beneficial on the track and even useful in autocross situations. A ducting kit can lower rotor temperatures by 20 to 30%. Porsche 996 GT3 (2001-2005) Brake Duct Spoilers are around $30 new and a great starting point for cooling glides. Ford Racing makes a Boss 302 ducting kit. However, if you are clever a home repair store trip can net you most of the ducting and zip ties to DIY.
Big Brake Kits (BBK)
BBKs do not make the car stop better. BBKs are just better heat sinks. 99.9% of cars with BBKs do not need BBKs. Stopping comes from pad drag coefficient and temperature control comes from pad material and ducts.
The Brembo setup on the GT package is very similar to other OEM Brembo brake systems. Benefit is quick change pad access.
Thanks for reading and happy racing!