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Brakes adequate Enough for 270
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mld22
Martin
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As Tama said earlier, upgrading the brakes should be done before any power increasing mods. Its common sense.
It may not be necessary but can only benefit the car.
Recently installed EP3 brakes on my standard EK9 and it has transformed the car. If the car is being used on track a brake upgrade will make a massive difference. Lap times will be boosted more by better brakes than minimal increases in power.
It may not be necessary but can only benefit the car.
Recently installed EP3 brakes on my standard EK9 and it has transformed the car. If the car is being used on track a brake upgrade will make a massive difference. Lap times will be boosted more by better brakes than minimal increases in power.
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question:
why is this thread in the wheel tire section?
if you have heavy wheels, then yes you should upgrade the brakes to slow that rotating weight.
if you have heavy tires and heavy wheels you should upgrade the brakes to slow that rotating weight.
Kozy, did you account for the weight of the wheels/tires in your calculations? If so what weight did you use per wheel/tire?
why is this thread in the wheel tire section?
if you have heavy wheels, then yes you should upgrade the brakes to slow that rotating weight.
if you have heavy tires and heavy wheels you should upgrade the brakes to slow that rotating weight.
Kozy, did you account for the weight of the wheels/tires in your calculations? If so what weight did you use per wheel/tire?
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That seems so not right Kozy.
19lbs of metal per wheel vs 11lbs is a huge difference in stopping distance, huge.
My ITR OEM 15s are very heavy with the RE11's
The TE37 with RA1's are very light...
The stopping distance between the two are very noticeable which also translates to heat at the disk.
But I also guess that different pads would do the same on heavy wheels or light wheels...so maybe it makes no difference? Then then again, how many heat cycles can each pad handle comes into play. This could go on forever with all the variables going around...lol get it? going around?
19lbs of metal per wheel vs 11lbs is a huge difference in stopping distance, huge.
My ITR OEM 15s are very heavy with the RE11's
The TE37 with RA1's are very light...
The stopping distance between the two are very noticeable which also translates to heat at the disk.
But I also guess that different pads would do the same on heavy wheels or light wheels...so maybe it makes no difference? Then then again, how many heat cycles can each pad handle comes into play. This could go on forever with all the variables going around...lol get it? going around?
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Rich777
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Does wheel weight actually make that much of a difference on it's own ? I'm looking at it more as the total mass of the whole systerm. I.e. the car. If I add 20kg extra wheel mass vs 20kg added onto the car's body why should the wheels make more of a difference ? The total momentum/KE will be the same for both won't it ?? P=mv KE= 0.5mv2 ?? Or am I being dumb again ? 
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What does a rotating mass actually do?
A rotating mass does not really consume energy. The mass just stores energy and eventually returns energy to the system or converts it to some other form of energy. The energy storage can be helpful, not do anything at all, or be harmful. With a little time and thought, we can understand how changes in rotating mass will affect available horsepower in a vehicle. Available horsepower in turn affects acceleration in a very predictable manner.
Four things determine the effect of rotating mass on our vehicles:
How quickly and often a rotating mass speeds up or slow down
How heavy the rotating mass is
The rotating weight's distance outwards from the centerline
How fast the weight spins
Here are the important things to worry about:
If we push energy into the rotating mass and pull energy out several times, obviously we move more power around than if we made a slow smooth change in speed.
The amount of weight is the least important thing! If we double the weight we only double the stored energy.
Distance weight is from the center line is very important, because it determines the weight's circular velocity (speed)! Stored energy goes up by the SQUARE of the radius change. If we replace a 4 inch diameter hollow driveshaft with an eight inch diameter tube of exactly the same weight, it has four times the stored energy!
The faster we spin the weight, the more energy it takes to move it and the more energy we must remove from that weight to slow it down. If we double the RPM, we multiply stored energy four times. Again it is a square of the change, just like number 1 was a square.
If we reduce mass from twenty pounds to ten pounds keeping the same distance out and same peak RPM, we reduce stored energy to half the original amount. Reducing weight is a one-for-one change.
If we reduce diameter by half while keeping the same weight and RPM, stored energy will be 1/4 the original stored energy. This change is a square. Twice is a "four times" effect. 2*2=4. Four times is a sixteen time effect on stored energy. 4*4=16
If we cut RPM in half, we would reduce stored energy to 1/4 the original amount. Once again this is a squared change. Change RPM three times, and the stored energy changes nine times. 3*3=9
We should carefully think about what this means when we change things. Some changes are worthwhile, some are not.
Wheel Changes
Let's assume, just for an example, all of the weight in a wheel is at the outer edge and remains at the outer edge. If we reduce a wheel's diameter but keep the overall weight the same, the wheel is a spinning ring with smaller diameter. The smaller diameter increases the wheel's RPM at the same vehicle speed. The smaller diameter also moves the spinning weight closer to the center.
Let's say we cut diameter in half. Now think about how fast the wheel spins. RPM will be twice what it was at the same speed. The half size diameter reduction spins the wheel twice as fast, and that would increase stored energy to four times the original amount if the weight was the same distance out.
The weight isn't the same distance out. The spinning weight is now half size. This 1/2 size reduction decreases stored energy by four times!
Because the same weight got closer to the center, but the increase in RPM increased stored energy, and payback is the same for both nothing changed.
In this example, we gained nothing at all with this change. We also lost nothing by the size change.
Lightening the tire or wheel would reduce stored energy, especially if the weight reduction was at the maximum distance out from the center. Here is an example where we want to make something as light as possible on the OUTER edge, not near the (wheel) center. Spending money on smaller or lighter rotors to save rotating weight is not a good use of money, because the rotating weight is close to the hub of the wheel. Unless the rotors are huge and we take weight out of the outermost edges of the rotors, things will not change much. (A light rotor is good for reducing un-sprung weight, and that helps keep our tire's in contact with the road. It also reduces vehicle weight. But this is a different problem. Here we are talking about rotation, not the bounce inertia or "dead weight".)
If we spent money on the same weight reduction in the wheel, reducing weight out a little further away from the center, we would do much better. We would be removing weight further out from the center, where it does the most good.
Which brings up an important point we almost never hear mentioned, a lower weight part might not be lighter at the outside edge. It might be lighter in the center, where the weight reduction doesn't mean much.
If we spent our money on a lighter tire we would be getting the very most return for the weight change. The tire's weight change is mostly outside between the rim edge and the tread area. We get maximum effect from the change!
Think about this carefully. If we buy a lighter tire, we know for sure the weight comes off the most critical area. If we buy a lighter rotor, it is close to the center and for the same weight change the return is much less.
The wheels also speed up and slow down gradually. With an 11-second car, we have 11 seconds to speed the wheel up. Most of the horsepower pushed into the wheel is pushed in near the end, when acceleration is least. Since we have more time to push the bigger amount of energy into the wheel, it takes less horsepower than we might expect. A little ways down, I'll show you how to determine the power if you know the speed, weight, and time.
Rotating Mass, Available Horsepower, and Acceleration
A rotating mass does not really consume energy. The mass just stores energy and eventually returns energy to the system or converts it to some other form of energy. The energy storage can be helpful, not do anything at all, or be harmful. With a little time and thought, we can understand how changes in rotating mass will affect available horsepower in a vehicle. Available horsepower in turn affects acceleration in a very predictable manner.
Four things determine the effect of rotating mass on our vehicles:
How quickly and often a rotating mass speeds up or slow down
How heavy the rotating mass is
The rotating weight's distance outwards from the centerline
How fast the weight spins
Here are the important things to worry about:
If we push energy into the rotating mass and pull energy out several times, obviously we move more power around than if we made a slow smooth change in speed.
The amount of weight is the least important thing! If we double the weight we only double the stored energy.
Distance weight is from the center line is very important, because it determines the weight's circular velocity (speed)! Stored energy goes up by the SQUARE of the radius change. If we replace a 4 inch diameter hollow driveshaft with an eight inch diameter tube of exactly the same weight, it has four times the stored energy!
The faster we spin the weight, the more energy it takes to move it and the more energy we must remove from that weight to slow it down. If we double the RPM, we multiply stored energy four times. Again it is a square of the change, just like number 1 was a square.
If we reduce mass from twenty pounds to ten pounds keeping the same distance out and same peak RPM, we reduce stored energy to half the original amount. Reducing weight is a one-for-one change.
If we reduce diameter by half while keeping the same weight and RPM, stored energy will be 1/4 the original stored energy. This change is a square. Twice is a "four times" effect. 2*2=4. Four times is a sixteen time effect on stored energy. 4*4=16
If we cut RPM in half, we would reduce stored energy to 1/4 the original amount. Once again this is a squared change. Change RPM three times, and the stored energy changes nine times. 3*3=9
We should carefully think about what this means when we change things. Some changes are worthwhile, some are not.
Wheel Changes
Let's assume, just for an example, all of the weight in a wheel is at the outer edge and remains at the outer edge. If we reduce a wheel's diameter but keep the overall weight the same, the wheel is a spinning ring with smaller diameter. The smaller diameter increases the wheel's RPM at the same vehicle speed. The smaller diameter also moves the spinning weight closer to the center.
Let's say we cut diameter in half. Now think about how fast the wheel spins. RPM will be twice what it was at the same speed. The half size diameter reduction spins the wheel twice as fast, and that would increase stored energy to four times the original amount if the weight was the same distance out.
The weight isn't the same distance out. The spinning weight is now half size. This 1/2 size reduction decreases stored energy by four times!
Because the same weight got closer to the center, but the increase in RPM increased stored energy, and payback is the same for both nothing changed.
In this example, we gained nothing at all with this change. We also lost nothing by the size change.
Lightening the tire or wheel would reduce stored energy, especially if the weight reduction was at the maximum distance out from the center. Here is an example where we want to make something as light as possible on the OUTER edge, not near the (wheel) center. Spending money on smaller or lighter rotors to save rotating weight is not a good use of money, because the rotating weight is close to the hub of the wheel. Unless the rotors are huge and we take weight out of the outermost edges of the rotors, things will not change much. (A light rotor is good for reducing un-sprung weight, and that helps keep our tire's in contact with the road. It also reduces vehicle weight. But this is a different problem. Here we are talking about rotation, not the bounce inertia or "dead weight".)
If we spent money on the same weight reduction in the wheel, reducing weight out a little further away from the center, we would do much better. We would be removing weight further out from the center, where it does the most good.
Which brings up an important point we almost never hear mentioned, a lower weight part might not be lighter at the outside edge. It might be lighter in the center, where the weight reduction doesn't mean much.
If we spent our money on a lighter tire we would be getting the very most return for the weight change. The tire's weight change is mostly outside between the rim edge and the tread area. We get maximum effect from the change!
Think about this carefully. If we buy a lighter tire, we know for sure the weight comes off the most critical area. If we buy a lighter rotor, it is close to the center and for the same weight change the return is much less.
The wheels also speed up and slow down gradually. With an 11-second car, we have 11 seconds to speed the wheel up. Most of the horsepower pushed into the wheel is pushed in near the end, when acceleration is least. Since we have more time to push the bigger amount of energy into the wheel, it takes less horsepower than we might expect. A little ways down, I'll show you how to determine the power if you know the speed, weight, and time.
Rotating Mass, Available Horsepower, and Acceleration
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Interesting point about the smaller/larger diameter effect cancelling itself out. The calcs show that up anyway, but I didn't connect the dots.
Lightweight tyres are definitely a good investment, pity so few people pay any attention to that.
Still, none the wiser as to whether the RKE of the wheels should be added to the KE of the car itself for braking purposes...
Lightweight tyres are definitely a good investment, pity so few people pay any attention to that.
Still, none the wiser as to whether the RKE of the wheels should be added to the KE of the car itself for braking purposes...
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^^^and where the weight is at on the wheel, outter part of the rim, or at the hub, makes a difference...makes some sense to converting to heat/performance. But how does that factor in is beyond me, you are the scientist not me.
I pay attention to weight of tires and wheels, well because Autox days trained me well. I was using a d16y8 in the coupe and needed to use what little available power there was most efficiently. Yet another reason to start out small, good teaching at the lower levels of performance driving.
I pay attention to weight of tires and wheels, well because Autox days trained me well. I was using a d16y8 in the coupe and needed to use what little available power there was most efficiently. Yet another reason to start out small, good teaching at the lower levels of performance driving.
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Cool stuff, makes me think wheel companies should invest in making wheels following some of the rules above.. I.e. making them not only lighter but in the right places
but then ... maybe they do ? i don't know lol, enjoyed reading it though
but then ... maybe they do ? i don't know lol, enjoyed reading it though
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Cool stuff, makes me think wheel companies should invest in making wheels following some of the rules above.. I.e. making them not only lighter but in the right places
but then ... maybe they do ? i don't know lol, enjoyed reading it though
oh they do! see Rays!
).gif ":)) :))")
If you have ever raced road bike, bicycles, you can feel the differences in your legs going from one wheel/tire to another...as well as in the pads and how they grind down. anywho... there are a ton of variables which makes it fun for me getting the right combo for each setup on cars.
Rich777
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Same here, there must be something else obvious that will explain it. If we have a car with the total KE of 320,000 J, then no matter what it will always take 320,000 J (opposing/brakes) to stop it.
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That's the bit which is really interesting to me about this hobby. I'm not really all that fussed about buying and fitting all the parts or having a build thread (partly because I have no money, partly because I quite like standard cars) but the dynamics are of real interest.
