Exotic-metal55

Very soon that is.. Will do a quck DIY and of course weigh everything as I go on my calibrated scales.

MRAMG1

Although they look GREAT, and should brake better

I'll take ANY bet that your times will remain the same, aka 1/4, and mile. Okay, you will be able to stop from 200+ MPH now

A 4400lb car minus 20 lbs?, just doesn't make a lot of difference.

Sorry Brad

PS: And I am well aware that this is unsprung weight boys and girls. Been doing that track thing now for over 20+ years

AND a BIG Good luck at the mile my friend

kamilclk430

Can't wait for the write up and your results from the MILE

Exotic-metal55

I am hoping for 34 lbs of un-sprung weight OFF but main thing is, I needed rotors! Mine are original, these look cool, great price, stop better and lighter. Every bit of weight helps IMO , especially in the 1/4 mile. Weight is not as big an issue in the mile as your drag coffeciant and frontal area become your weight. Stopping is an issue, so these rotors with Akebono pads and then there is NO FEAR.

E55Dimon

Curious as to why you got these just slotted? I also have these but drilled/slotted.

AgSilver

It does make complete physical sense. Reduce the rotational mass
and you release the HP needed to turn the object. As an example of how serious this is taken in the real world of performance, the reverse gear on every F1 gearbox has holes cut in it for lightness as strength is not required. As H.G. Wells wrote: It's the little things . . .

AgSilver

You'll like 'em. Your butt dyno will confirm it. Not to mention the improvement in handling as a result of the reduction of un-sprung weight.

AKnight55

Do you ever have anything positive to say?

MRAMG1

YES, when it actually works

Sorry guys, but I have been doing this for a LLLLOOONNNGGG time, and have wasted untolds amount of money on placebo effects.

I wish you, the OP the best at the mile and the drag

MRAMG1

Being an engineer myself, I must say that you are 100% correct in your example

However, and there is usually a however, think about total unsprung mass here. F1's are in a whole different ball park, by a factor of about maybe 1 or 2 decimals points. AKA Michael Schumacher would NOT see the difference in 20lbs in an E55 on a road circuit. Sorry, but physics never lie

AKnight55

I agree, but when you add it all up it WILL make a difference.. When your talking 20 lbs from the rotors and maybe 20 lbs from wheels of un-sprung weight and with a lighter battery and weight savings from the exhaust, your starting to talk about some serious weight savings.. Like another member said, It all adds up

Exotic-metal55

Here is how 20 lbs can make or break a year. You wait for the right day (cold , dry and ultra high barometer ) to go for your PB. Maybe it is a 10 second pass and you get one shot, as you dont have a roll cage. You make the run and it is an 11.02 and you explode with frustration and second guessing. Most anyone that 1/4 miles a lot, knows this scenario. You then say , damn! I should have emptied my glove box out, ran 1/8th tank of gas, lighter rotors, less or no wiper fluid, etc. etc.

I hate that frustration so bad, that not even a pair of sun glasses stay in the car. 20 lbs can easilly be worth 02. Either way, needed rotors, more braking and the lighter weight is a bonus in this case.

320 dreamer

exotic-metal55 did you check with brad about the akebono pads? if the brinnel hardness is above 250 you may not want ceramic pads. i have the r/b rotors and they wont warrenty them if ceramics are used. i went with hawk hos semi metallics and have no dust or noise and r/b approves. just dont want you to have any issues if the pads arent company approved

chiromikey

these are the pads evosport now recommends after the problems ebc reds caused...

320 dreamer

good to go then!! i know r/b had some issues with the ceramics on some subi's during a track day so now they only want semi metallics. i had akebonos on my last 32 and loved them but im really suprised how quiet the hawk hps pads are. and virtually no dust. rob at needswings got me a great price.

Zod

Just make sure you do the break pad pedding in process correctly

or be repaired for shaky ruff breaking when your pushing the car around..

AgSilver

When it comes to reducing un-sprung weight by about 10-15% per wheel, that's quite a reduction of bound, re-bound inertia. Overwhelmingly noticeable by me. Add HP and go faster on the straights, add lightness and go fast everywhere . . . C. Chapman

Jon2007E63P30

In the application the OP notes, makes no difference. In a very severe track condition, drilled rotors crack. Slots do not. That is why i went with Racing Brake in the fronts, and I like the harder metal.

MRAMG1

Bottom line, on a 4400lb vehicle, your lap times are NOT going to change. Sorry, but true.

Been there, done that in the world challange series my friend. And that was in a 3400lb vehicle.

Can it hurt, obviously NOT, are you going to see a real world difference, well I'll just leave it at that

PS: In Exotic's quest for the Mile and draggin, ANY wieght reduction can only help. Besides as he stated he needed new rotors anyway, so why not.

But for road racing, I stand by my original statment for the E55.

MRAMG1

+1

Thericker

rotarynews.com

Unsprung weight and rotational inertia, as we know, is more important than sprung weight. The general rule of thumb says that 1 pound rotational or unsprung weight is approx equal to 10 pounds static

IE if he saves 20-30 lbs total in all 4 rotors = 200-300 Static or Sprung weight savings, rule of thumb every 10 lbs static weight savings worth 1 HP Brooks will FREE UP 20-30 HP very viable acceleration advantage. If Brooks adds lighter wheels & tires it'll compound these savings further hence MB vid below. I've personally seen up to 25-30 HP loss or gain on DynoJet DynoDynamic dynos w/16"-20" wheel setups etc

http://youtu.be/AaO40PRc69Y

MRAMG1

Just in case some of you have forgotten the last time this stuff came up:

Effects
Unsprung vs. sprung weight have no difference in their effect on acceleration or top speed. There is no “1-10” rule (or any other ratio) where 1 lb. removed from unsprung weight “has the same same effect as” a higher amount of sprung weight. Any benefit from weight reduction towards increased MPH or reduced ET will be exactly the same as if the weight were removed from the chassis. Weight removed from an unsprung component, such as a rear wheel or axle housing, may affect traction if the wheel is not under control during launch.
Lighter wheels & tires do have a very small additional benefit due to the lower amount of power required to rotate them (true of all rotating components), but this is not due to their classification as unsprung weight.
The unsprung vs. sprung weight percentage greatly affects wheel control, but its importance is almost entirely limited to un-even surfaces, or conditions where the attitude of the vehicle changes (such as through G forces). This is most important in off-road and pavement road racing, somewhat less important in dirt track, and has almost no value in drag racing. As the importance of suspension travel for proper wheel control diminishes, the value of reducing the unsprung proportion of the total car weight is lessened, and becomes zero if the suspension travel is zero.
Cars requiring precise control of wheel movement, where a low percentage of unsprung weight is an advantage, will have faster lap times and higher top speeds, not because unsprung weight reduction improves acceleration or top speed, but because traction is improved.
The unsprung vs. sprung weight percentage also affects ride comfort, since lighter springs are needed to maintain traction and control with lighter unsprung components (alloy wheels, independent rear suspension, alloy calipers, composite springs, in-board brakes, etc.), the chassis is less disturbed by wheel movement and road surface irregularities.

PS: Not my writing, do you own searchs for physics lessons please

MRAMG1

Rotainal mass IS very important, just as you said about wheel's. I am sure many here have seen it on a dyno, including myslef.
Bottom line, it is YOUR money, do with it whatever you want

But I will take the bet, that your 1/4 mile times and MPH don't change

Thericker

Tell that to SGC Renn Tech, those exact changes Ceramic rotors/lighter drag setup Carbon Fiber drive shaft led to their latest 1/4 mile records in E/T & MPH Trap speed increases.
IDK what or why you continue to argue these FACTS I'm done w/disscussing this believe what you wil.. Brooks cl will benefit in both aspects

1995E320Cab

I am NO expert in this matter, the only real experience that I have is this.....

I had the original Audi TT it was a fun little car on the forged stock wheels. I got a set of very lightweight wheels for it, they where the same size over all, but man could you feel the difference (it was night and day !) off the line and I would say in the 0-25MPH range. After that I was always sold on lightweight wheels / tires. I also noticed a better / smother ride.