brake mod?
07-13-05, 11:59 AM
#2
Originally Posted by JDMHARRIER
has anyone done a brake mod on the rx300? looking to upgrade to something better.
07-13-05, 02:40 PM
#3
No one makes a BBK for RX300. Rotora makes slotted rotors. I have Brembo blank in front and Rotora slotted at rear (see pic). I have Akebono's ceramic pads, less dust, more bite, with moderate friction coefficient. Lexus designed rear pads to NOT cover the inside of rotor, I thought it was Rotora's design flaw until I saw stock RX300s have the same look.
Last edited by TunedRX300; 07-13-05 at 02:43 PM.
07-13-05, 09:08 PM
#4
Moderator
Originally Posted by JDMHARRIER
hey ... has anyone done a brake mod on the rx300? looking to upgrade to something better. the brake on the rx300 isnt that great..
There are couple of assumptions I made in the above statement [1. Your brakes are in good working order. 2. The tire to pavement patch remains the samebefore and after any mod].
Counter-intutive right? If we ignore the effect of ABS ... it will be the same in before and after mod... Assuming that you can lock the wheel from spinning before and after the mod the real slow down will be due to the friction of the tire with pavement.
Salim
07-13-05, 09:49 PM
#5
Brake pads have a lot to do with stopping distance. Higher(average) friction coefficient means it requires smaller amount of force to make a stop. Brake fade due to heat is not the only reason that braking is ineffective and nothing else can be improved.
Here is the formula - given the same F, higher Mue means less W.
COEFFICIENT OF FRICTION
The scientific definition for coefficient of friction is the ratio of force required to move or stop one surface, with a given perpendicular force applied to it, as it drags across another surface. The layman can think of coefficient as the slippage of the pad as it clamps down on the rotor. The coefficient measurement ranges from zero to infinity, but most racing pad's range from .15 to .65. The mathematical formula for coefficient of friction is:
Mue = F/W
Where:
Mue = coefficient of friction
F = force required to move one surface over the other
W = perpendicular force
Brake dusts do not affect braking distance directly but most people do not like the look of a black or pink layer on their rims. Brake dusts are also corrosive - see the bubble near the top of my picture. It is left by dusts came from OEM semi-metallic pads.
Here is the formula - given the same F, higher Mue means less W.
COEFFICIENT OF FRICTION
The scientific definition for coefficient of friction is the ratio of force required to move or stop one surface, with a given perpendicular force applied to it, as it drags across another surface. The layman can think of coefficient as the slippage of the pad as it clamps down on the rotor. The coefficient measurement ranges from zero to infinity, but most racing pad's range from .15 to .65. The mathematical formula for coefficient of friction is:
Mue = F/W
Where:
Mue = coefficient of friction
F = force required to move one surface over the other
W = perpendicular force
Brake dusts do not affect braking distance directly but most people do not like the look of a black or pink layer on their rims. Brake dusts are also corrosive - see the bubble near the top of my picture. It is left by dusts came from OEM semi-metallic pads.
Last edited by TunedRX300; 07-14-05 at 01:22 AM.
07-13-05, 10:35 PM
#6
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my brake is working fine ... there no problem with it at all ... i m just looking for upgrade ... something better ... cause i did a grade on my girlfriend SC...just feeling the differences on it after the upgrade was done and the way it look...
07-14-05, 01:18 AM
#7
Bleed your brake lines, let air come out . It is the cheapest mod that will allow you to transfer pressure. Again, brake fluid bleed or flush restore your braking independent of fade due to heat.
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07-14-05, 06:26 AM
#8
Moderator
Originally Posted by TunedRX300
Brake pads have a lot to do with stopping distance. Higher friction coefficient means it requires smaller amount of force to make a stop.
Here is the formula - given the same F, higher Mue means less W.
COEFFICIENT OF FRICTION
The scientific definition for coefficient of friction is the ratio of force required to move or stop one surface, with a given perpendicular force applied to it, as it drags across another surface. The layman can think of coefficient as the slippage of the pad as it clamps down on the rotor. The coefficient measurement ranges from zero to infinity, but most racing pad's range from .15 to .65. The mathematical formula for coefficient of friction is:
Mue = F/W
Where:
Mue = coefficient of friction
F = force required to move one surface over the other
W = perpendicular force
Brake dusts do not affect braking distance directly but most people do not like the look of a black or pink layer on their rims. Brake dusts are also corrosive - see the bubble near the top of my picture. It is left by dusts came from OEM semi-metallic pads.
Here is the formula - given the same F, higher Mue means less W.
COEFFICIENT OF FRICTION
The scientific definition for coefficient of friction is the ratio of force required to move or stop one surface, with a given perpendicular force applied to it, as it drags across another surface. The layman can think of coefficient as the slippage of the pad as it clamps down on the rotor. The coefficient measurement ranges from zero to infinity, but most racing pad's range from .15 to .65. The mathematical formula for coefficient of friction is:
Mue = F/W
Where:
Mue = coefficient of friction
F = force required to move one surface over the other
W = perpendicular force
Brake dusts do not affect braking distance directly but most people do not like the look of a black or pink layer on their rims. Brake dusts are also corrosive - see the bubble near the top of my picture. It is left by dusts came from OEM semi-metallic pads.
Overall I see we agree with each other ... brake mod may make a difference in the feel and with any pad worth its name the driver can lock the rotating wheel (again abs may release it). The difference will be in the amount of force.
The science in brake pads is in how they dissipate heat and how much of the heat is passed on to the brake fluid. This is where a good pad would shine by minimizing the fade. The friction during fade goes so low that any amount of reasonable force will not be able to lock the wheel and also the brake fluid might change from a non-compressable liquid to vapors.
<removed>. Payload lbs affect the stopping distance more than the pads itself.
Salim
Salim
Last edited by salimshah; 07-16-05 at 05:40 PM.
07-14-05, 07:57 AM
#9
Super Moderator
I also painted my calipers and have experimented with some different pads (Hawk Performance and EBC). The newer Lexus pads work just fine for me even in the hilly terrain and awful drivers here in Mexico City. Listen to TunedRX300 on rotors and pads. 
I also use Valvoline Powersyn Brake Fluid. Some of the Castrol Brake Fluids are also very good, especially the SRF, but expensive. Valvoline fluids can be found in virtually any Autozone. I also use their Powersyn Power Steering Fluid, though Mobil 1 ATF (have friend with 2001 RX300 down here using it) will work along with Redline ATF (which may be the best stuff but for sports cars).
I also use Valvoline Powersyn Brake Fluid. Some of the Castrol Brake Fluids are also very good, especially the SRF, but expensive. Valvoline fluids can be found in virtually any Autozone. I also use their Powersyn Power Steering Fluid, though Mobil 1 ATF (have friend with 2001 RX300 down here using it) will work along with Redline ATF (which may be the best stuff but for sports cars).
07-14-05, 11:58 AM
#10
Originally Posted by salimshah
Overall I see we agree with each other ... brake mod may make a difference in the feel and with any pad worth its name the driver can lock the rotating wheel (again abs may release it). The difference will be in the amount of force.
The science in brake pads is in how they dissipate heat and how much of the heat is passed on to the brake fluid. This is where a good pad would shine by minimizing the fade. The friction during fade goes so low that any amount of reasonable force will not be able to lock the wheel and also the brake fluid might change from a non-compressable liquid to vapors.
It's your $$ and your choice to spend it as you like, but dont expect that change in stopping difference. Payload lbs affect the stopping distance more than the pads itself.
Salim
Salim
The science in brake pads is in how they dissipate heat and how much of the heat is passed on to the brake fluid. This is where a good pad would shine by minimizing the fade. The friction during fade goes so low that any amount of reasonable force will not be able to lock the wheel and also the brake fluid might change from a non-compressable liquid to vapors.
It's your $$ and your choice to spend it as you like, but dont expect that change in stopping difference. Payload lbs affect the stopping distance more than the pads itself.
Salim
Salim
Bigger rotor also helps indepedent of heat fade, for same amount of force applied, bigger rotor diameter yields higher torque. I am sure everyone understand the principle - such as breaker bar - nandle length is purposely made longer than a regular socket wrench so you can break a tight plug with same or less amount of force.
Lexus pads are expensive, for the same $ ($45 for front Akebono pair) I can always find a much better pads with better thermal recovery and higher stopping. If you still wish to use your OEM pad, you can always wait until they wear out to go for better replacement pads.
Last edited by TunedRX300; 07-14-05 at 01:56 PM.
07-14-05, 12:16 PM
#11
Originally Posted by Lexmex
I also painted my calipers and have experimented with some different pads (Hawk Performance and EBC). The newer Lexus pads work just fine for me even in the hilly terrain and awful drivers here in Mexico City. Listen to TunedRX300 on rotors and pads.
I also use Valvoline Powersyn Brake Fluid. Some of the Castrol Brake Fluids are also very good, especially the SRF, but expensive. Valvoline fluids can be found in virtually any Autozone. I also use their Powersyn Power Steering Fluid, though Mobil 1 ATF (have friend with 2001 RX300 down here using it) will work along with Redline ATF (which may be the best stuff but for sports cars).
I also use Valvoline Powersyn Brake Fluid. Some of the Castrol Brake Fluids are also very good, especially the SRF, but expensive. Valvoline fluids can be found in virtually any Autozone. I also use their Powersyn Power Steering Fluid, though Mobil 1 ATF (have friend with 2001 RX300 down here using it) will work along with Redline ATF (which may be the best stuff but for sports cars).
I was looking for Power Steering Fluid, thanks for posting. I will probably go with Mobil 1 to replace my PS Fluid.
07-14-05, 07:51 PM
#13
Moderator
Folks:
I neither want to belabor the point nor want be misunderstood. Some how I have rolled a lot more in to the "feel". My defination of "feel" also includes brake-pedal travel, sponginess, break neck respose and much much more. Surly one set up can be better that the other. My viewpoint is that if you measure the stopping distance in an emergency braking dont expect much differnce. ... with the caveat of fading ... [we can split hair by adding msec it takes for the differene in foot travel].
So what is the big deal .... This issue is counter intutive and it did take me a while to accept it.
Increased torque means less effort (feel) but the work-done does not change... [If only I could relate it in in terms of braking]
For folks who are thinking about painting the caliper ... keep two things in mind..
1. Examine the wheel assembly and see how much of the caliper is visible .. no need to paint more than necessary.
2. Brake fluid is extreemly bad for paint. So keep the painted surface away from the bleed points.
Salim
I neither want to belabor the point nor want be misunderstood. Some how I have rolled a lot more in to the "feel". My defination of "feel" also includes brake-pedal travel, sponginess, break neck respose and much much more. Surly one set up can be better that the other. My viewpoint is that if you measure the stopping distance in an emergency braking dont expect much differnce. ... with the caveat of fading ... [we can split hair by adding msec it takes for the differene in foot travel].
So what is the big deal .... This issue is counter intutive and it did take me a while to accept it.
Increased torque means less effort (feel) but the work-done does not change... [If only I could relate it in in terms of braking]
For folks who are thinking about painting the caliper ... keep two things in mind..
1. Examine the wheel assembly and see how much of the caliper is visible .. no need to paint more than necessary.
2. Brake fluid is extreemly bad for paint. So keep the painted surface away from the bleed points.
Salim
07-14-05, 11:42 PM
#14
Check this link out
Brake System 101
Few quotes
"The job of the braking system is to change that kinetic energy to heat energy and dissipate this heat into the air"
"Braking performance: At lower speeds, the rate of energy delivered to the rotor is much less than the rate that energy can leave the rotor into the air. The brakes are overwhelming the tires. The only way to improve braking is to exert more force on the car, which means to install better tires. At higher speeds, the rate of energy delivered to the rotor is significantly larger. There is a speed where that rate is larger than the rate at which the rotor can dump heat into the air and at that point the tires start overwhelming the brakes. To improve braking at higher speeds one must install larger brakes and/or have air ducts to the brakes, etc. Basically anything to help the rotors dump the heat into the air faster."
"To increase the rate at which energy arrives at the rotor you can:
# increase the size of the rotor
# increase the size of the pad
# increase the friction of the pad by going to a different one.
# increase the friction of the pad by distributing the force more evenly (two or more piston calipers.)
# upgrade your tires
To increase the rate at which the energy leaves the rotor you can:
# increase the mass of the rotor
# improve the shape of the rotor (directional vanes, larger surface, etc.)
# improve the heat transfer properties of the rotor (ceramic brakes etc.)
# install air ducts."
Brake System 101
Few quotes
"The job of the braking system is to change that kinetic energy to heat energy and dissipate this heat into the air"
"Braking performance: At lower speeds, the rate of energy delivered to the rotor is much less than the rate that energy can leave the rotor into the air. The brakes are overwhelming the tires. The only way to improve braking is to exert more force on the car, which means to install better tires. At higher speeds, the rate of energy delivered to the rotor is significantly larger. There is a speed where that rate is larger than the rate at which the rotor can dump heat into the air and at that point the tires start overwhelming the brakes. To improve braking at higher speeds one must install larger brakes and/or have air ducts to the brakes, etc. Basically anything to help the rotors dump the heat into the air faster."
"To increase the rate at which energy arrives at the rotor you can:
# increase the size of the rotor
# increase the size of the pad
# increase the friction of the pad by going to a different one.
# increase the friction of the pad by distributing the force more evenly (two or more piston calipers.)
# upgrade your tires
To increase the rate at which the energy leaves the rotor you can:
# increase the mass of the rotor
# improve the shape of the rotor (directional vanes, larger surface, etc.)
# improve the heat transfer properties of the rotor (ceramic brakes etc.)
# install air ducts."
Last edited by TunedRX300; 07-14-05 at 11:48 PM.
