Front wave rotors
06-01-2002, 05:35 AM
#111
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Here's a (stupid?) question...
How about the best of both worlds? Why not make the wave rotors out of iron? You'd still get the better cooling and some of the weight savings of the wave design AND the added heat resistance and lower cost of an iron rotor, right? Would the weight savings be so negligible that it'd be a waste of time? Just curious...
By the way, I love the design...very innovative and unique (until the ricers find out about it anyway
). The only thing keeping these brakes off by car is my lack of funding
.
One other thing...how about a dyno pull with the lightweight rear rotors? I bet you could get a couple rwhp just from the weight savings. Just a thought.
How about the best of both worlds? Why not make the wave rotors out of iron? You'd still get the better cooling and some of the weight savings of the wave design AND the added heat resistance and lower cost of an iron rotor, right? Would the weight savings be so negligible that it'd be a waste of time? Just curious...
By the way, I love the design...very innovative and unique (until the ricers find out about it anyway
). The only thing keeping these brakes off by car is my lack of funding . One other thing...how about a dyno pull with the lightweight rear rotors? I bet you could get a couple rwhp just from the weight savings. Just a thought.
06-01-2002, 12:51 PM
#112
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dave22,
You can actually run some numbers estimates for power losses from rotating mass in the drivetrain. For something like a wheel, a loss of 5 lbs or so (depending on where you lose the 5 lbs) is good for about 3-5 hp in 1st gear, and less in each higher gear thereafter - the amount of loss actually depends upon acceleration rates and is actually calculated as a torque. As a brake rotor has a much smaller moment of inertia (MoI) it will have a smaller benefit, especially if the primary weight loss is coming from the hat, which by itself has a smaller MoI than the actual rotor (basically, look at how far the mass is from the center of rotation to get an idea about the magnitude of MoI). I would expect taht you would see less than 1 hp gain on a chassis dyno. However, weight loss is good, and rotating weight loss is better. Plus, there could be a benefit in suspension performance - although not a major one.
UL
You can actually run some numbers estimates for power losses from rotating mass in the drivetrain. For something like a wheel, a loss of 5 lbs or so (depending on where you lose the 5 lbs) is good for about 3-5 hp in 1st gear, and less in each higher gear thereafter - the amount of loss actually depends upon acceleration rates and is actually calculated as a torque. As a brake rotor has a much smaller moment of inertia (MoI) it will have a smaller benefit, especially if the primary weight loss is coming from the hat, which by itself has a smaller MoI than the actual rotor (basically, look at how far the mass is from the center of rotation to get an idea about the magnitude of MoI). I would expect taht you would see less than 1 hp gain on a chassis dyno. However, weight loss is good, and rotating weight loss is better. Plus, there could be a benefit in suspension performance - although not a major one.
UL
06-01-2002, 03:24 PM
#114
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UL, right on! Couldn't have typed it better. Mind if I cut and paste this for all the ricers that say they are getting cross-drilled rotors for lower weight so they can have better acceleration??
06-01-2002, 03:31 PM
#115
Besides cost, is there a trade off of getting cross-drilled rotors?
I like the wave design. Very unique.
I noticed while riding my Brother's motorcycle that the brakes make a whining sound, it's very faint, but really cool.
That would be cool to have on my car.
I like the wave design. Very unique.
I noticed while riding my Brother's motorcycle that the brakes make a whining sound, it's very faint, but really cool.
That would be cool to have on my car.
06-01-2002, 07:46 PM
#116
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The reason that we don't use a cast iron rotor of this design , is the material is not strong enough to survive . Companies have tried to produce this style of rotor from cast iron with very bad results . When the cast iron fails the pieces explode and fly every where. Steel is a much stronger material than cast iron , it wasn't until the design and the thermal treating process was perfected that this type of rotor could take the abuse and not warp.
Most of the performance advantage in reducing the weight of the components is handling . The shocks and springs must handle the weight of the standard components . Removing 9 Lbs. of unsprung weight per wheel is a huge reduction.
The ability of the steel rotor to provide a friction surface , the same as cast iron , is not a problem .They are so close that you would have a hard time measuring the difference.
Regarding cross drilling , see above . This weight saving for the ability of providing faster acceleration , no way ! You could never measure the slight weight savings difference between cross drilled and non-drilled rotors . Keep in mind that these rotors are steel and the holes don't create problems with the rotors , like cast iron rotors do.
I don't know if it is "cool " or not but the rear rotors do make this noise . Our guess is the air that is trapped under the pads , in the holes , and then heated creates , this phenomenon.
I was sent a White Paper that Warren Gilliland wrote years ago , regarding rotor selection . I will contact Rick and we will post it on his site and will put link in this forum.
BBSpoon
If your rear rotors and front rotors are running 900 degrees F you have a problem , the rears should not be running that hot . The day at Button Willow all three cars that we tested , none of the rear rotors were over 500F and my car at Nelson Ledges was just reaching 400F.
As for rotor temperatures you are correct that certain pads do require temperatures in a range to be effective and out of this range they are hard to predict their performance . We recommend a #3 racing pad that has a range of 150F to 1200F with very little change in CF over its entire operating range. This means that if your rears are running 400 and your fronts are running 850 the CF at both ends of the car is the same .
I will through out one more item that some of you will have to live with . Some racing pads require a certain level of temperature to be reached ( hot) or they become grinding pads wearing your rotors . Race cars that are only used on the track and driven only at speed don't have a problem delivering this heat . But a car driven on the street or to and from the track can find problems with high rotor wear .
One other problem with a sliding caliper ( stock one ) is the ability of the caliper to back away from the rotor , creating heat ( and slowing the car ) when the brake petal is released ,between corners . By using a four piston design you eliminate the friction of the sliding pins and the twisting of the caliper . The four piston design also spreads the load from the pistons on the pad better , eliminating any bent backer plates . If the caliper is very stiff , the pistons retract back into the caliper bores , creating very little drag. The only item resisting retraction , is the o-rings in the caliper.
brad
Most of the performance advantage in reducing the weight of the components is handling . The shocks and springs must handle the weight of the standard components . Removing 9 Lbs. of unsprung weight per wheel is a huge reduction.
The ability of the steel rotor to provide a friction surface , the same as cast iron , is not a problem .They are so close that you would have a hard time measuring the difference.
Regarding cross drilling , see above . This weight saving for the ability of providing faster acceleration , no way ! You could never measure the slight weight savings difference between cross drilled and non-drilled rotors . Keep in mind that these rotors are steel and the holes don't create problems with the rotors , like cast iron rotors do.
I don't know if it is "cool " or not but the rear rotors do make this noise . Our guess is the air that is trapped under the pads , in the holes , and then heated creates , this phenomenon.
I was sent a White Paper that Warren Gilliland wrote years ago , regarding rotor selection . I will contact Rick and we will post it on his site and will put link in this forum.
BBSpoon
If your rear rotors and front rotors are running 900 degrees F you have a problem , the rears should not be running that hot . The day at Button Willow all three cars that we tested , none of the rear rotors were over 500F and my car at Nelson Ledges was just reaching 400F.
As for rotor temperatures you are correct that certain pads do require temperatures in a range to be effective and out of this range they are hard to predict their performance . We recommend a #3 racing pad that has a range of 150F to 1200F with very little change in CF over its entire operating range. This means that if your rears are running 400 and your fronts are running 850 the CF at both ends of the car is the same .
I will through out one more item that some of you will have to live with . Some racing pads require a certain level of temperature to be reached ( hot) or they become grinding pads wearing your rotors . Race cars that are only used on the track and driven only at speed don't have a problem delivering this heat . But a car driven on the street or to and from the track can find problems with high rotor wear .
One other problem with a sliding caliper ( stock one ) is the ability of the caliper to back away from the rotor , creating heat ( and slowing the car ) when the brake petal is released ,between corners . By using a four piston design you eliminate the friction of the sliding pins and the twisting of the caliper . The four piston design also spreads the load from the pistons on the pad better , eliminating any bent backer plates . If the caliper is very stiff , the pistons retract back into the caliper bores , creating very little drag. The only item resisting retraction , is the o-rings in the caliper.
brad
06-01-2002, 07:51 PM
#117
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PS
I dug out my material strengths tables :
7075-T6 aluminum
At 75 degrees =73,000 psi
At 212 =63,000
At 300 =31,000
At 400 =16,000
How hot do you think the attachment points of the rotor to hat get?
brad
I dug out my material strengths tables :
7075-T6 aluminum
At 75 degrees =73,000 psi
At 212 =63,000
At 300 =31,000
At 400 =16,000
How hot do you think the attachment points of the rotor to hat get?
brad
06-02-2002, 02:54 AM
#118
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dwb1,
As for the the temps. I have changed springs and during hard braking experience considerably less dive. I am also running and 205 front and 245 rear Toyo RA-1s. 7.7 inches wide and 9.5 inches wide, respectively. When I used XP fronts and Hawk Blue rears I got 900F fronts/1100F rears. I've also gotten 1100F rear with porterfield R4S installed. I use the "Smart-Temp" paint, one bottle paint temp kit. Color changes with temperature, accuracy is 100 degrees. Problem is the color chart, its only 5 distinct colors. You have to take a guess if the color you got is in between the colors of the chart. And 10 out of 10 the color you get an in-betweener. These temperatures were taken from Summit Point and Watkins Glen.
I'm aware of the corrosive and abrasive nature of pads. Fortunately, the pads I'm using now don't have these problems.
I also aware of the limitations of the single piston floating brake design. I'm considering the 4 piston Nissin caliper by Spoon. It uses the same pad as the stock calipers. However, doesn't fit the stock wheels, duh!
Does anybody know if these calipers fit the Volks CE28N wheels? Anyway, I'm far off from making a decision. I'll wait for your test results.
Thanks
As for the the temps. I have changed springs and during hard braking experience considerably less dive. I am also running and 205 front and 245 rear Toyo RA-1s. 7.7 inches wide and 9.5 inches wide, respectively. When I used XP fronts and Hawk Blue rears I got 900F fronts/1100F rears. I've also gotten 1100F rear with porterfield R4S installed. I use the "Smart-Temp" paint, one bottle paint temp kit. Color changes with temperature, accuracy is 100 degrees. Problem is the color chart, its only 5 distinct colors. You have to take a guess if the color you got is in between the colors of the chart. And 10 out of 10 the color you get an in-betweener. These temperatures were taken from Summit Point and Watkins Glen.
I'm aware of the corrosive and abrasive nature of pads. Fortunately, the pads I'm using now don't have these problems.
I also aware of the limitations of the single piston floating brake design. I'm considering the 4 piston Nissin caliper by Spoon. It uses the same pad as the stock calipers. However, doesn't fit the stock wheels, duh!
Does anybody know if these calipers fit the Volks CE28N wheels? Anyway, I'm far off from making a decision. I'll wait for your test results.Thanks
06-02-2002, 05:07 AM
#120
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dwb1,
Some afterthoughts,
Those temp readings are they from your brake kit or from the OE brake system?
Mikey was with me last year at Summit Point testing Panther Plus pads. I can't remember his rear temp readings but I remember that we had identical front temp readings and he uses stock springs and stock tires. I e-mailed him for some info. I remember getting 1200-1100F fronts and rears. Using the H&R springs, Toyo RA-1s and Panther Plus front, Porterfield R4S rears.
Hey Mikey!! If your around and reading this. Please post those number thanks.
BTW, we both had the dust/heat shield installed.
Are those tracks hard on brakes? I know that Summit and The Glen are both hard on brakes.
Some afterthoughts,
Those temp readings are they from your brake kit or from the OE brake system?
Mikey was with me last year at Summit Point testing Panther Plus pads. I can't remember his rear temp readings but I remember that we had identical front temp readings and he uses stock springs and stock tires. I e-mailed him for some info. I remember getting 1200-1100F fronts and rears. Using the H&R springs, Toyo RA-1s and Panther Plus front, Porterfield R4S rears.
Hey Mikey!! If your around and reading this. Please post those number thanks.
BTW, we both had the dust/heat shield installed.
Are those tracks hard on brakes? I know that Summit and The Glen are both hard on brakes.