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'07 Exige S
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Discussion Starter · #1 ·
The last part of my brake upgrade has been completed. I did the two pot (38.10mm) rear conversion with Frank Jacko's awesome e-brake mod this winter.
Last night the new BOE two piece fixed hat rotors went on. Can't wait to get some time on these. Rotor weight savings for all four is claimed to be 11lbs.

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Hi Henry, did you weigh the rotors?? I have the same ones and they are pretty much the same weight as the stock item. Very disappointed after spending a fair bit of $$$ for lighter rotors.
 

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07 Aspen White Exige S - MT
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Hi Henry, did you weigh the rotors?? I have the same ones and they are pretty much the same weight as the stock item. Very disappointed after spending a fair bit of $$$ for lighter rotors.
Concur, there is hardly any weight savings when I weighed mine this winter.
 

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This is copied straight from the Boe website, can you say false advertising. They are talking 5lbs/corner for the Elise, total BS.

Save Weight with a full set of Evora rotors saving about 11lbs of rotational mass and a full set of Elise/Exige rotors saving about 20lbs of rotating mass!
 

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Not to derail the OP's thread, but it should come as no surprise that the rotors aren't substantially lighter. Conversely, BOE and others shouldn't be advertising incorrect mass savings - that's just embarrassing for them.

If the rotors were substantially lighter, they would overheat during track events or even during one stop from top speed. The brakes are heat sinks to convert kinetic energy into thermal heat. In order to stay within thermal limits of cast iron, you have to have enough mass of iron to absorb the energy. If you don't have enough mass, you overheat the cast iron and start to rupture the surfaces of the rotor. The only real mass savings opportunity is converting the rotor hub material from iron to aluminum, iron being about 2.5-3 times greater density than aluminum. .... or you switch to carbon-carbon or carbon ceramic rotors that can handle higher temperatures.
 

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07 Aspen White Exige S - MT
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Not to derail the OP's thread, but it should come as no surprise that the rotors aren't substantially lighter. Conversely, BOE and others shouldn't be advertising incorrect mass savings - that's just embarrassing for them.

If the rotors were substantially lighter, they would overheat during track events or even during one stop from top speed. The brakes are heat sinks to convert kinetic energy into thermal heat. In order to stay within thermal limits of cast iron, you have to have enough mass of iron to absorb the energy. If you don't have enough mass, you overheat the cast iron and start to rupture the surfaces of the rotor. The only real mass savings opportunity is converting the rotor hub material from iron to aluminum, iron being about 2.5-3 times greater density than aluminum. .... or you switch to carbon-carbon or carbon ceramic rotors that can handle higher temperatures.
Not to derail even further but @jdawson hows that build coming? I miss reading your progress :)
 

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'07 Exige S
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Discussion Starter · #9 ·
Hi Henry, did you weigh the rotors?? I have the same ones and they are pretty much the same weight as the stock item. Very disappointed after spending a fair bit of $$$ for lighter rotors.
dummy me, no!! every night they were sitting on the blanket in the garage I kept saying "get the scale" and I forgot. BOE claims 11lbs. You found zero??
 

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dummy me, no!! every night they were sitting on the blanket in the garage I kept saying "get the scale" and I forgot. BOE claims 11lbs. You found zero??
Boe claims 20lbs for Elige, 11lbs for Evora
There was a very small difference, somewhere around 0.5lbs, definitely nowhere near 5lbs. 🤨🤬
 

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Discussion Starter · #12 ·
Boe claims 20lbs for Elige, 11lbs for Evora
There was a very small difference, somewhere around 0.5lbs, definitely nowhere near 5lbs. 🤨🤬
as previously stated the only weight savings are in the hats. Steel vs. aluminum. I was dubious of 11lbs. 20lbs, fat chance.
 

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I think I found about 1.0-1.5lb or so per corner. But I think this can vary depending on previous rotor wear and the amount of material that was eaten off the old rotor I removed.
 

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2006 Exige
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I think I found about 1.0-1.5lb or so per corner. But I think this can vary depending on previous rotor wear and the amount of material that was eaten off the old rotor I removed.
Good point about rotor wear. It would be hard to believe a rotor with an aluminum hat doesn’t save weight.Stock rotors weigh 13#2oz
Inokinetic ultra disk is 11#7oz,so about 1.5#saving.
Don’t have boe rotors to weigh.
Performance friction rotor is 10# 8oz the lightest rotor I am aware of.Saves 2#10oz per wheel.As a small bonus it’s 295mm dia. so it has a little more surface area to get rid of heat.
 

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I weighed my fixed 2-piece 288 mm rotors from BOE at 11.5 lb when they were new. That is consistent with the slightly heavier floating style (but same generation) shown above at 11.6 lb.

Therefore a realistic weight saving expectation is 6 to 7 pounds for a set of four BOE 288 mm rotors. Those that found less likely compared to worn originals. Keep in mind each rotor will have lost about a full pound at the wear limit.
 

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We use a larger hat in the rear on our ULTRAdisc to create additional weights savings. We've been selling the same design since 2005 with legit weight savings.

 

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Good point about rotor wear. It would be hard to believe a rotor with an aluminum hat doesn’t save weight.Stock rotors weigh 13#2oz
Inokinetic ultra disk is 11#7oz,so about 1.5#saving.
Don’t have boe rotors to weigh.
Performance friction rotor is 10# 8oz the lightest rotor I am aware of.Saves 2#10oz per wheel.As a small bonus it’s 295mm dia. so it has a little more surface area to get rid of heat.
Do the PFC 295mm rotors fit with the OEM and APR CP5316 calipers (I assume so from your post but just checking)?
 

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2006 Exige
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Do the PFC 295mm rotors fit with the OEM and APR CP5316 calipers (I assume so from your post but just checking)?
Yes they work with APR calipers they do require a 3.5mm spacer between caliper and upright due to there larger OD.Besides being the lightest they are
an alloy that doesn’t seem to wear. I brake hard enough that I don’t use ds2500 pads anymore. I cooked them but didn’t even wear the rotors.
 

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Yes they work with APR calipers they do require a 3.5mm spacer between caliper and upright due to there larger OD.Besides being the lightest they are
an alloy that doesn’t seem to wear. I brake hard enough that I don’t use ds2500 pads anymore. I cooked them but didn’t even wear the rotors.
Many thanks, nice to hear similar experiences. I use Shinoo's Ultradiscs and get loooong service from them!

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