OEM Brembo Brakes updated for the RC F
08-27-14 | 10:41 PM
#16
But they are NOT using steel rotors, so heat is less if an issue. In every brake pad there is the friction material which is held together with some sort of resin. Once brake pads starts to get too hot, the resin holding the pad material together starts to vaporize, forming a gas. That gas has to have somewhere to go, because it can't stay between the pad and the rotor, so it forms a thin layer between the two trying to escape. The result is very similar to aquaplaning while going too fast in the rain; the pads lose contact with the rotor, thus reducing the amount of friction. Hence the use of slots, cross drilling, etc.
Hopefully, that puts the issue to bed.
Hopefully, that puts the issue to bed.
08-28-14 | 05:32 AM
#17
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From: PA
But they are NOT using steel rotors, so heat is less if an issue. In every brake pad there is the friction material which is held together with some sort of resin. Once brake pads starts to get too hot, the resin holding the pad material together starts to vaporize, forming a gas. That gas has to have somewhere to go, because it can't stay between the pad and the rotor, so it forms a thin layer between the two trying to escape. The result is very similar to aquaplaning while going too fast in the rain; the pads lose contact with the rotor, thus reducing the amount of friction. Hence the use of slots, cross drilling, etc.
Hopefully, that puts the issue to bed.
Hopefully, that puts the issue to bed.
08-28-14 | 07:44 AM
#18
Gassing isn't much of an issue, especially with today's pad. When you reach the point of 'too hot', it's usually the brake fluid that boils prior to the resin vaporizing in large amounts. Boiling brake fluid will encourage brake fade long before gas in between the rotor and pad.
08-28-14 | 01:59 PM
#19
But they are NOT using steel rotors, so heat is less if an issue. In every brake pad there is the friction material which is held together with some sort of resin. Once brake pads starts to get too hot, the resin holding the pad material together starts to vaporize, forming a gas. That gas has to have somewhere to go, because it can't stay between the pad and the rotor, so it forms a thin layer between the two trying to escape. The result is very similar to aquaplaning while going too fast in the rain; the pads lose contact with the rotor, thus reducing the amount of friction. Hence the use of slots, cross drilling, etc.
Hopefully, that puts the issue to bed.
Hopefully, that puts the issue to bed.
BTW, no production car has ever used steel rotors. They are gray cast iron. Only motorcycles use steel because it looks prettier naked and doesn't corrode the way cast iron does. Cast iron has a much higher surface coefficient of friction and is preferred in all cases where carbon fiber is illegal or too expensive.
08-28-14 | 02:05 PM
#20
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Joined: Aug 2005
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From: ƒ(x)
If it were 1965 and we were still using asbestos for brake linings, I would agree with you. Unfortunately, this is complete misinformation about modern brake systems. They do not outgas and do not need holes, slots, or grooves in the rotors to produce maximum friction. Let's focus on technology from 2008 when they started working on this project. No modern pad does this.
BTW, no production car has ever used steel rotors. They are gray cast iron. Only motorcycles use steel because it looks prettier naked and doesn't corrode the way cast iron does. Cast iron has a much higher surface coefficient of friction and is preferred in all cases where carbon fiber is illegal or too expensive.
BTW, no production car has ever used steel rotors. They are gray cast iron. Only motorcycles use steel because it looks prettier naked and doesn't corrode the way cast iron does. Cast iron has a much higher surface coefficient of friction and is preferred in all cases where carbon fiber is illegal or too expensive.
08-28-14 | 02:10 PM
#21
Who is F1? How about James Walker, a world renowned brake engineer who designs and builds braking and stability control systems for OEMs? He says the holes do nothing of the sort.
http://www.scirocco.org/faq/brakes/p...oorrotors.html
http://training.sae.org/seminars/c0718/ Scroll down for his bio.
Crossdrilling your rotors might look neat, but what is it really doing for you? Well, unless your car is using brake pads from the '40s and 50s, not a whole lot. Rotors were first drilled because early brake pad materials gave off gasses when heated to racing temperatures, a process known as "gassing out." These gasses then formed a thin layer between the brake pad face and the rotor, acting as a lubricant and effectively lowering the coefficient of friction. The holes were implemented to give the gasses somewhere to go. It was an effective solution, but today's friction materials do not exhibit the some gassing out phenomenon as the early pads.
For this reason, the holes have carried over more as a design feature than a performance feature. Contrary to popular belief, they don't lower temperatures. (In fact, by removing weight from the rotor, they can actually cause temperatures to increase a little.) These holes create stress risers that allow the rotor to crack sooner, and make a mess of brake pads--sort of like a cheese grater rubbing against them at every stop. Want more evidence? Look at NASCAR or F1. You would think that if drilling holes in the rotor was the hot ticket, these teams would be doing it.
For this reason, the holes have carried over more as a design feature than a performance feature. Contrary to popular belief, they don't lower temperatures. (In fact, by removing weight from the rotor, they can actually cause temperatures to increase a little.) These holes create stress risers that allow the rotor to crack sooner, and make a mess of brake pads--sort of like a cheese grater rubbing against them at every stop. Want more evidence? Look at NASCAR or F1. You would think that if drilling holes in the rotor was the hot ticket, these teams would be doing it.
http://training.sae.org/seminars/c0718/ Scroll down for his bio.
Last edited by lobuxracer; 08-28-14 at 02:28 PM.
09-04-14 | 09:34 PM
#22
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From: Under an IS F since 2008
Originally Posted by 2015 Lexus RC F Press Kit
Braking Good
The Lexus RC F driver will know the car is going to deliver on the track from the first run through the gears. The first stop will instill equal confidence in the brakes.
The RC F gets an exclusive brake package featuring 15-inch diameter spiral-fin front rotors, improved brake cooling and a vertical g-sensor as part of the anti-lock brake system control. The vertical g-sensor came as a result of extensive testing at the Nürburgring. It allows for changes in vertical loads, and hence optimizes control of braking force the instant load returns to the tires after jumping a crest.
Testing on the Nürburgring has also ensured that RC F brakes offer the ultimate in sports performance, direct feel, cooling and durability.
Compared with the IS F, front-rotor diameter has been increased by 0.8-inch and rear rotor thickness by 0.2-inch The RC F’s 15-inch by 1.3-inch ventilated front rotors are slotted rather than drilled, with six-piston opposed calipers. The rear brake rotors are 13.6-inch by 1.1-inch ventilated, with four-piston opposed calipers.
The new, larger rotors help ensure linear controllability in all g-force ranges during continuous track driving, while providing a direct feeling during everyday driving. The pads are designed to ensure long life and reduced chance of uneven wear. The new RC F brakes also reduce booming noise during high-speed braking.
The hardware also includes a new brake booster and master cylinder design and a new high-rigidity pedal, to enhance response and shorten pedal stroke, with g-force generated aligning with pedal stroke.
Exclusive RC F hydraulic control circuitry optimizes brake control and the interaction with the new ABS/VDIM Mode Select feature. The improved ABS operates in harmony with RC F’s optional Torque-Vectoring Differential, to suitably control drive force and braking force at each of the four wheels.
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