caliper & rotor weight = major or minor difference?
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caliper & rotor weight = major or minor difference?
Questions:
1) For auto-x is it better (more efficent & good enough) to go with the lightest rotor/pad combo and spend money highend pads (carbotech, cobalt)?
2) The difference between ITR calipers, 11.1" rotors & HF calipers/9" rotors is 28 LBS
How much does that matter on the track in terms of performance?
To keep it simple for arugment sate...lets ssuming the car:
2200-2500 lbs
under 250 whp
I know that the caliper is no considered to be "rotoating mass" but still mass non the less.
FACTS:
Weight for PAIR "Loaded Calipers" :
ITR = 28 lbs
GSR/EX = 18 lbs
DX/LX = 15 lbs
HF = 13 lbs
*note all are different in pad suraface area & piston size
Weight for PAIR of front rotors:
Prelude 11.1" rotors = 27 lbs
GSR/EX 10.3" rotors = 22 lbs
DX/LX 9.4" rotors = 20 lbs
HF 9" rotors = 14 lbs
Weight of front calipers & rotors:
ITR calipers + 11.1" = 55 lbs
GSR calipers + 10.3" = 40 lbs
DX/LX calipers + 9.4" = 35 lbs
HF calipers + 9" = 27 lbs
ITR calipers + 10.3" =50lbs *hybrid combo
..... Thoughts?
1) For auto-x is it better (more efficent & good enough) to go with the lightest rotor/pad combo and spend money highend pads (carbotech, cobalt)?
2) The difference between ITR calipers, 11.1" rotors & HF calipers/9" rotors is 28 LBS
How much does that matter on the track in terms of performance?
To keep it simple for arugment sate...lets ssuming the car:
2200-2500 lbs
under 250 whp
I know that the caliper is no considered to be "rotoating mass" but still mass non the less.
FACTS:
Weight for PAIR "Loaded Calipers" :
ITR = 28 lbs
GSR/EX = 18 lbs
DX/LX = 15 lbs
HF = 13 lbs
*note all are different in pad suraface area & piston size
Weight for PAIR of front rotors:
Prelude 11.1" rotors = 27 lbs
GSR/EX 10.3" rotors = 22 lbs
DX/LX 9.4" rotors = 20 lbs
HF 9" rotors = 14 lbs
Weight of front calipers & rotors:
ITR calipers + 11.1" = 55 lbs
GSR calipers + 10.3" = 40 lbs
DX/LX calipers + 9.4" = 35 lbs
HF calipers + 9" = 27 lbs
ITR calipers + 10.3" =50lbs *hybrid combo
..... Thoughts?
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Re: caliper & rotor weight = major or minor difference?
Keep it light for autox!!!!!! All brake are, are heat sinks and you will not build enough heat in a 60 sec run to need a larger rotor. If you can lock them up with smaller brakes.... big wont be better. Just make sure you are using a more agressive ft pad. I have a CRX that is CSP prepped and I can lock up V710's all over the place with stock brakes if I'm not carfull. And becuase weigh is important I'll be replacing my ITR brakes on my H2 car with Spoon janks as soon as I can get my hand on a set.
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Re: caliper & rotor weight = major or minor difference?
That's my thoughts exactly but just wanted to know for sure.
In that case would 9" HF rotors be optimal (granted I'm using a much more aggressive pad)
In that case would 9" HF rotors be optimal (granted I'm using a much more aggressive pad)
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Re: caliper & rotor weight = major or minor difference?
Don't forget the aluminum rear drums. Not sure how much weight they save though.
Edit: For 2.) The tiny brakes will be destroyed on a big track, so performance is...finishing the session/race vs. not. The brakes are sort of enough for a stock-motor car (IT cars are doing it), but for anything else they just aren't enough.
Edit: For 2.) The tiny brakes will be destroyed on a big track, so performance is...finishing the session/race vs. not. The brakes are sort of enough for a stock-motor car (IT cars are doing it), but for anything else they just aren't enough.
#7
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Re: caliper & rotor weight = major or minor difference?
1986-87 CRX HF rear drums (aluminum body with iron braking surface/liner) are 4 lbs each versus the all steel version from the other models at 7 lbs each.
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#8
Re: caliper & rotor weight = major or minor difference?
I did the HP loss calculations a few days ago. Please understand this is only an estimate. The only way I can get a more accurate number is if someone wants to cut their rotor into three pieces and weigh them for me, I have to pretend the rotor is a uniform disc.
0-90 mph in 15.5s:
ITR Rotor 11.1" 14lbs: 38.57Watts - 0.0517HP
LS Rotor 10" 12lbs: 27.38Watts - 0.0367HP
These numbers are per rotor, so it would be double those numbers per axle.
Also, just for fun I put in the 1/4 mile time for my brother's cavalier (12.2 @ 124 mph) and for the ITR Rotors it worked out to 93 watts or 0.1245 HP and for he LS Rotors it was 66.011 Watts or 0.08849 HP.
However, the moment of inertia for the rotors are not 100% Accurate. Brake rotors have most of their mass on the outer part, but I don't have enough data about the rotors to accurately model that it. Therefore I used the moment of inertia calculation for a uniform disc.
All calculations were done with a tire size of 205/50-15 as well. With a larger tire, the hp loss due to the rotor would be less. (HP loss due to the tire would increase.)
Also, this is based on average HP over an entire 1/4 Mile run.
0-90 mph in 15.5s:
ITR Rotor 11.1" 14lbs: 38.57Watts - 0.0517HP
LS Rotor 10" 12lbs: 27.38Watts - 0.0367HP
These numbers are per rotor, so it would be double those numbers per axle.
Also, just for fun I put in the 1/4 mile time for my brother's cavalier (12.2 @ 124 mph) and for the ITR Rotors it worked out to 93 watts or 0.1245 HP and for he LS Rotors it was 66.011 Watts or 0.08849 HP.
However, the moment of inertia for the rotors are not 100% Accurate. Brake rotors have most of their mass on the outer part, but I don't have enough data about the rotors to accurately model that it. Therefore I used the moment of inertia calculation for a uniform disc.
All calculations were done with a tire size of 205/50-15 as well. With a larger tire, the hp loss due to the rotor would be less. (HP loss due to the tire would increase.)
Also, this is based on average HP over an entire 1/4 Mile run.
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Re: caliper & rotor weight = major or minor difference?
Interesting calculation d1ck. I remember one from years ago about unsprung weight, where Xlbs of unsprung weight (calipers, rotors, wheel, etc.) = Ylbs of sprung weight, and Y would be a higher number. Basically, it would be equivalent to taking out so much weight from the interior or whatever, and basing speeds/times off that. The hp angle is a new one though
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Re: caliper & rotor weight = major or minor difference?
I couldn't image that there would be that much big difference between 9.0" & 9.4"
it's not like going from 9.4" civic to 10.3" gsr setup....
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Re: caliper & rotor weight = major or minor difference?
I'd also be surprised at that, knowing that some ~200hp SM cars have used the lesser base-model Integra brakes just fine with the right pad selection (which would be sort of equivalent to the comparison above).
#14
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Re: caliper & rotor weight = major or minor difference?
great post OP! have you hardcore ax'er found brake ducting to be worth while on ax? i would imagine true even on a short course... can't hurt right?
#15
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Re: caliper & rotor weight = major or minor difference?
some people run non-vented disks upfront, basically what is normally a rear setup on the front. they claim the unsprung weight saving is more important for autox, but where we race there is very little braking involved, so i would have to agree. this annoys the hell out of me because i run rsx-s brakes all around lol, but on the street or road course nothing compares to massive brakes on a light car
the majority of autox courses are too short and there is too much wait time between runs to really worry about heat soaking the braking system. that being said because speeds are relatively low the small hit you take to aero is mostly negligible.
the majority of autox courses are too short and there is too much wait time between runs to really worry about heat soaking the braking system. that being said because speeds are relatively low the small hit you take to aero is mostly negligible.
#17
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Re: caliper & rotor weight = major or minor difference?
IMO if you can't lock your tires you don't have enough braking power. But you shouldn't be able to lock your tires instantly or easily. I really don't think 15lbs is substantial in brakes because most of that is caliper weight and not rotating. Also the benefits far exceed the minimal weight increase.
#18
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Re: caliper & rotor weight = major or minor difference?
I can tell you that running a lighter caliper does make a big difference. The steering feel is lighter and makes it feel more effortless. That was actually the first thing I noticed after installing aluminum calipers.
#19
Re: caliper & rotor weight = major or minor difference?
Rotating unprung weight (rotors) is by far the best place to lose weight in a car. Static unsprung weight (calipers) is the second best place to lose it.
As small as you can go whilst being able to comfortably lock the brakes and have them not fade on you is the way to go. I swapped back from 11.1" to 10.3" rotors as the bigger ones made the car worse in a variety of ways.
As small as you can go whilst being able to comfortably lock the brakes and have them not fade on you is the way to go. I swapped back from 11.1" to 10.3" rotors as the bigger ones made the car worse in a variety of ways.
#20
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Re: caliper & rotor weight = major or minor difference?
Easiest place to shave weight... I agree. It's also the most expensive place. 2 piece rotors and forged billet calipers are incredibly high in price. Take Spoon calipers for example, they use the same pads as an ITR caliper but are 5 times the price of brand new ITR calipers from Honda. Better stopping power? No, simply lighter weight and maybe better modulation. 2 piece rotors now initial cost is high because of the hat but replacement rotors are about the same. I like the Wilwood brake kits but I do think they are a waste for gaining more stopping power over a 11.1 or 11.8 OEM brake upgrade. Brembo, Stoptech, AP Racing... those will put you through the windshield if your tires can handle them.
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02-14-2002 10:37 AM