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> Myth Busting: Crossdrilled Rotors
But she looked 18 of..
    Posted: May 15 2005, 03:52 PM


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QUOTE
(Taken from a sticky at Celicatech)
Since I know folks will be eventually asking about this I figured it
would be better to head off this disaster before it gets ugly. Here is
the response I made to a different forum a few months ago after
collecting some information:

===========
First, lets get some physics. Tell me how a heatsink with less mass will
cool better? You do realize that a brake rotor acts as a large heatsink
to transfer heat from the brake pads to the rotor. The heat generated
from pads has to go somewhere and so it transfers to the rotor and
caliper.

Porsche claims: "Discs are cross-drilled to enhance braking in the wet.
The brakes respond faster because the water vapour pressure that builds
up during braking can be released more easily."
They have said nothing about enhancing normal braking circumstances and
the larger diameter rotors probably make up for the lack of material
present in a smaller cross drilled rotor.

From Wilwood's website:
QUOTE
Q:  Why are some rotors drilled or slotted?
A: Rotors are drilled to reduce rotating weight, an issue near and dear
to racers searching for ways to minimize unsprung weight. Drilling
diminishes a rotor's durability and cooling capacity.

Slots or grooves in rotor faces are partly a carryover from the days of
asbestos pads. Asbestos and other organic pads were prone to "glazing"
and the slots tended to help "scrape or de-glaze" them.  Drilling and
slotting rotors has become popular in street applications for their pure
aesthetic value. Wilwood has a large selection of drilled and slotted
rotors for a wide range of applications

As for the Porsche rotors..
QUOTE

1) The holes are cast in giving a dense boundary layer-type crystalline
grain structure around the hole at the microscopic level as opposed to
drilling which cuts holes in the existing grain pattern leaving open
endgrains, etc, just begging for cracks.
2) The holes are only 1/2 the diameter of the holes in most drilled
rotors. This reduces the stress concentration factor due to hole
interaction which is a function (not linear) of hole diameters and the
distance between them.
3) Since the holes are only 1/2 as big they remove only 1/4 as much
surface area and mass from the rotor faces as a larger hole. This does a
couple of things:
It increases effective pad area compared with larger holes. The larger
the pad area the cooler they will run, all else being equal. If the same
amount of heat is generated over a larger surface area it will result in
a lower temperature for both surfaces.
It increases the mass the rotor has to absorb heat with. If the same
amount of heat is put into a rotor with a larger mass, it will result in
a lower temperature.
3) The holes are placed along the vanes, actually cutting into them
giving the vane a "half moon" cut along its width. You can see that
here:
user posted image

This does a couple of things:
First, it greatly increases the surface area of the vanes which allows
the entire rotors to run cooler which helps prevent cracks by itself.

Second, it effectively stops cracking on that side of the hole which
makes it very difficult to get "hole to hole" cracks that go all the way
through the face rotor (you'll get tiny surface "spider cracks" on any
rotor, blank included if you look hard enough).

That's why Porsche rotors are the only "crossdrilled" rotors I would
ever consider putting on my car.

BTW, many of the above features are not present in older Porsche brakes.
The above is for "Big Reds" and newer.


This is quite different from the standard drilled rotors you get from
brembo/kvr/powerslot/"insert random ricer parts brand name here" brake
rotors.

Further proof of the uselessness of cross drilled rotors are found here:
http://www.teamscr.com/rotors.htm


QUOTE
Crossdrilling your rotors might look neat, but what is it really
doing for you? Well, unless your car is using brake pads from the 40’s
and 50’s, not a whole lot. Rotors were first ‘drilled’ because early
brake pad materials gave off gasses when heated to racing temperatures –
a process known as ‘gassing out’. These gasses then formed a thin layer
between the brake pad face and the rotor, acting as a lubricant and

effectively lowering the coefficient of friction. The holes were
implemented to give the gasses ‘somewhere to go’. It was an effective
solution, but today’s friction materials do not exhibit the same gassing
out phenomenon as the early pads.

For this reason, the holes have carried over more as a design feature
than a performance feature. Contrary to popular belief they don’t lower
temperatures (in fact, by removing weight from the rotor, the
temperatures can actually increase a little), they create stress risers
allowing the rotor to crack sooner, and make a mess of brake pads – sort
of like a cheese grater rubbing against them at every stop. (Want more
evidence? Look at NASCAR or F1. You would think that if drilling holes
in the rotor was the hot ticket, these teams would be doing it.)

The one glaring exception here is in the rare situation where the rotors
are so oversized (look at any performance motorcycle or lighter formula
car) that the rotors are drilled like Swiss cheese. While the issues of
stress risers and brake pad wear are still present, drilling is used to
reduce the mass of the parts in spite of these concerns. Remember –
nothing comes for free. If these teams switched to non-drilled rotors,
they would see lower operating temperatures and longer brake pad life –
at the expense of higher weight. It’s all about trade-offs.


From Stoptech
QUOTE
Which is better, slotted or drilled rotors?
StopTech provides rotors slotted, drilled or plain. For most performance
applications slotted is the preferred choice. Slotting helps wipe away
debris from between the pad and rotor as well as increasing the "bite"
characteristics of the pad. A drilled rotor provides the same type of
benefit, but is more susceptible to cracking under severe usage. Many
customers prefer the look of a drilled rotor and for street and
occasional light duty track use they will work fine. For more severe
applications, we recommend slotted rotors.


That almost sounds like an excuse to use cross drilled rotors, and for
your street car which probably is never driven on the track, the drilled
rotors are fine, but as Stoptech states, they will crack and are not
good for severe applications.

From Baer:
QUOTE
"What are the benefits to Crossdrilling, Slotting, and
Zinc-Washing my rotors?

In years past, crossdrilling and/or Slotting the rotor for racing
purposes was beneficial by providing a way to expel the gasses created
when the bonding agents employed to manufacture the pads...However, with
today’s race pad technology, ‘outgassing’ is no longer much of a
concern...Slotted surfaces are what Baer recommends for track only use.
Slotted only rotors are offered as an option for any of Baer’s
offerings."


Then from Grassroots Motorsports:
QUOTE
"Crossdrilling your rotors might look neat, but what is it really
doing for you? Well, unless your car is using brake pads from the '40s
and 50s, not a whole lot. Rotors were first drilled because early brake
pad materials gave off gasses when heated to racing temperatures, a
process known as "gassing out." ...It was an effective solution, but
today's friction materials do not exhibit the some gassing out
phenomenon as the early pads. Contrary to popular belief, they don't
lower temperatures. (In fact, by removing weight from the rotor, they
can actually cause temperatures to increase a little.)
These holes
create stress risers that allow the rotor to crack sooner, and make a
mess of brake pads--sort of like a cheese grater rubbing against them at
every stop. Want more evidence? Look at NASCAR or F1. You would think
that if drilling holes in the rotor was the hot ticket, these teams
would be doing it...Slotting rotors, on the other hand, might be a
consideration if your sanctioning body allows for it. Cutting thin slots
across the face of the rotor can actually help to clean the face of the
brake pads over time, helping to reduce the glazing often found during
high-speed use which can lower the coefficient of friction. While there
may still be a small concern over creating stress risers in the face of
the rotor, if the slots are shallow and cut properly, the trade-off
appears to be worth the risk. (Have you looked at a NASCAR rotor
lately?)


And then, let's check out what was said on the aforementioned Altima
thread (Long thread at altimas.net that was deleted by that server. it
is hosted here)

QUOTE
Here is how it works. The friction between the pad and rotor is
what causes you to stop. This friction converts your forward energy into
heat (remember Einstein: Energy is neither created nor destroyed, it is
converted). Now that heat is a bad thing. Yes it is bad for the rotors
but it is a lot worse for the pads. A warped rotor will still stop the
car - it will just feel like shit. Overheated pads however WILL NOT stop
the car. It is here where the rotors secondary responsibility comes in.
Its job now is to DISSIPATE the heat away from the pads and DISPERSE it
through itself. Notice that DISSIPATE and DISPERSE are interchangeable?
Once the heat is removed from the pad/surface area it is then removed.
Notice where the removal falls on the list of duties? That's right -
number 3. Here is the list again. Memorize it because I will be using it
a lot in this post:

#1 Maintains a coefficient of friction with the pad to slow the forward
inertia of the vehicle

#2 DISSIPATE the heat

#3 REMOVE the heat from the brake system

Let's look more in-depth at each step now shall we? No? Too bad assclown
we are doing it anyway.

#1 Maintains a coefficient of friction with the pad to slow the
forward inertia of the vehicle:

This one is pretty simple and self-explanatory. The rotor's surface is
where the pads contact and generate friction to slow the vehicle down.
Since it is this friction that causes the conversion of forward
acceleration into deceleration (negative acceleration if you want) you
ideally want as much as possible right? The more friction you have the
better your stopping will be. This is reason #1 why BIGGER brakes are
the best way to improve a vehicle's stopping ability. More surface area
on the pad and the rotor = more friction = better stopping. Does that
make sense Ace? Good. Let's move on.
#2 DISSIPATE The Heat:
Let's assume for a second that the vehicle in question is running with
Hawk (Seiji) (Seiji) (Seiji) Blue pads on it. The brand doesn't really matter but that is what I
am using as my example. They have an operating range of 400 degrees to
1100 degrees. Once they exceed that 1100 degree mark they fade from
overheating. The pad material gets too soft to work effectively -
glazing occurs. This means that a layer of crude glass forms on the
surface of the pad. As we all know glass is very smooth and very hard.
It doesn't have a very high coefficient of friction. This is bad -
especially when I am coming down the back straight at VIR at 125MPH.
Lucky for us the rotor has a job to do here as well. The rotor, by way
of thermal tranfer DISSIPATES the heat throughout itself. This
DISSIPATION lessens the amount of heat at the contact area because it is
diluted throughout the whole rotor. The bigger the rotor the better here
as well. The more metal it has the more metal the heat can be diluted
into. Make sense? This isn't rocket science here d00d.
#3 REMOVE the heat from the brake system:
Now comes your favorite part of the process. This is what you thought
DISSIPATION was. It is ok. I will allow you to be wrong. This is the
step where the rotor takes the heat it DISSIPATED from the pads and gets
rid of it for good. How does it do this? By radiating it to the surface
- either the faces or inside the veins. It is here where cool air
interacts with the hot metal to cool it off and remove the heat. Once
again there is a reoccuring theme of "the bigger the better" here. The
bigger the rotor, the more surface area it will have which means more
contact with the cooling air surrounding it. Got it? Good.
Now let's look at why cross-drilling is a bad idea.
First - as we have already established, cross-drilling was never done to
aid in cooling. Its purpose was to remove the worn away pad material so
that the surfaces remained clean. As we all know this doesn't have much
of a purpose nowadays.
Next - In terms of cooling: Yes - x-drilling does create more areas for
air to go through but remember - this is step 3 on the list of tasks.
Let's look at how this affects steps 1 and 2. The drilling of the rotor
removes material from the unit. This removal means less surface area for
generating surface friction as well as less material to accept the
DISSIPATED heat that was generated by the friction. Now because of this
I want to optimize step one and 2 since those are the immediate needs.
If it takes longer for the rotor to get rid of the heat it is ok. You
will have a straight at some point where you can rest the brakes and let
your cooling ducts do their job. My PRIMARY concern is making sure that
my car slows down at the end of the straight. This means that the rotor
needs to have as much surface as possible to generate as much friction
as possible and it needs to DISSIPATE the resulting heat AWAY from the
pads as quick as possible so they continue to work. In both cases
x-drilling does nothing to help the cause.
Now let's talk about strength - and how x-drilled rotors lack it. This
one is simple. Explain again just how drilling away material/structure
from a CAST product DOES NOT weaken it? Since you are obviously a man of
great knowledge and experience surely you have seen what can happen to a
x-drilled rotor on track right? Yes it can happen to a non-drilled rotor
as well but the odds are in your favor when pimpin' bling-bling drilled
y0! Since you are also an expert on thermodynamics why not explain to
the group what happens to a cast iron molecule when it is overheated. I
will give you a little hint - the covalence bonds weaken. These bonds
are what hold the molecules together boys and girls. You do the math -
it adds up to fractures.
So why don't race teams use them if they are so much better?
Consistency? Hmmmm . . . no. I am gonna go with the real reason her
chodeboy. It is because of several factors actually. They are as follows
but in no particular order:

- Less usable surface area for generating friction
- Less material to DISSIPATE the heat away from the pads
- Less reliable and they are a safety risk because of fatigue and stress
resulting from the reduced material

And what are the benefits? Removal of particulate matter and enhanced
heat removal. I gotta tell ya - it is a tough choice but I think I am
going to stick with the safe, reliable, effective-for-my-stopping needs
solution Tex.


Thank you, please drive through.

======================

So basically, buy them if you think they look cool, but not if you think
this will be an acceptable performance upgrade.


This post has been edited by Nick on May 15 2005, 04:07 PM
sideways
Posted: May 15 2005, 05:43 PM


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Pin worthy cool.gif but this should probably be in the Tech section, ill let it get some attention here then pin her up in the tech

This post has been edited by sidewaysgts on May 15 2005, 05:43 PM
WRX DEMON Type R
Posted: May 15 2005, 05:59 PM


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im too lazy to read all that.

i am looking to completely replace my car's pads and rotors...

Suggestion please?
But she looked 18 of..
  Posted: May 15 2005, 06:24 PM


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I will suggest you quit being lazy and do some research. There is a LOT more to getting the right braket setup then what many people go by which is "bigger is better".
Think about exactly what it is about your current brakes that you are not satisfied with and what type of driving will your car be experiencing.
FWIW When Brad Bedell's mk2 mr2 won the Sport Compact Car Magazine, Ultimate Street Car Challenge, he was using 94/95turbo mr2 brakes with real good pads and had the lowest stopping distance of any car they had ever tested.
A good set of brake pads can do wonders for your car.
Also remember, brakes dont stop the car, the tires do.

*edit: If your really set on spending money I would suggest going with STi brake setup. They have had a lot of testing done for those cars. You could probably get a good set of 2nd hand brakes from someone with out too much money.

This post has been edited by Nick on May 15 2005, 06:36 PM
Nd4SpdSe
Posted: May 15 2005, 07:26 PM


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sideways
Posted: May 15 2005, 07:36 PM


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To keep it simple because they look good. Nicks post was dead on and used a number of resources, common sense with physics will also support the claims made. They want a car the looks and performs good.

As nick touched, hands down the BEST way to increase your braking ability are the pads. If your getting brake fade due to overheating you need to flush out your system and upgrade your fluid. If you want to upgrade your rotors, sloted is the best path to go. Any thing that builds up between the rotor and the pad has a place to go, plus the egde gives the slicing effect should the pads start to glaze. They suppoedly bring the life of your pads down but its minimal, so no worries- small price to pay for the advantage imo.

NFS i still suggest you upgrade your fluid as well, its not a sin to mix fluid, and as long as you flush it properly youll do fine. Bleed the rear passenger until your getting the new fluid going through, rear driver, front passenger, then front driver (from the furthest to closest).
WRX DEMON Type R
Posted: May 15 2005, 08:25 PM


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my brake rotors are rusted (what i get for keeping the car locked up for nearly 3 moths) and the car makes noises when i press the brakes.

hey, anyone know if Monroe brakes are any good? www.monroebrakes.com

I can grab these at Canadian Tire. Rotors and pads.
ATM the car is just for transportation. No fancy NAWZ or drifting for me. LOL.
Cubits
Posted: May 15 2005, 09:10 PM


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Slots-b-good. Even the most uber-modern pads will glaze from light pedal use etc, and slots don't really diminish the pad life much. The slots may weaken the disc slightly, but it is quite an insignificant amount in most cases.

Drilled are pretty bad. If you don't get hole-cast discs, it will create issues. If you say, got the brakes nice and hot on a mountain road, then hit a puddle, you'd probably warp or even crack the discs (badness).

I've seen semi-drilled discs (EBC make em) that are slotted too. Pretty sure the hemispherical dents are only for street appeal, but at least they'll be stronger than fully-drilled discs. They're cast holes.
Jabberwocky
Posted: May 15 2005, 10:21 PM


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Let me start off by saying that what nick posted was true.

Cross drilled rotors are not without their application. It is a viable way to reduce unsprung weight/rotational mass. Usually a cross drilled rotor of the same thickness will have less mass. Thus be a worst heatsink. In some cases, this trade off is worth it, especially is the car already has more than adequate braking. Eg. if the car can lock all 4 wheels at any time.

The other way to reduce the rotational mass of the rotor is to make it thinner. Which can make it more prone to warping. Or decrease the size of the rotor. Which also reduces the surface area. Reducing the mass of the rotor usually involves some kind of trade off no matter how you look at it.

From what I've seen, high price cars with drilled rotors usually also have massively powerful braking systems. A slight reduction in unsprung weight could very well be worth the tradeoff since the braking system far exceeds the traction of the tires anyways.

I think only cheap pads glaze. The good ones aren't suppose to.

This post has been edited by Jabberwocky on May 15 2005, 10:28 PM
Cubits
Posted: May 15 2005, 11:47 PM


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If i had more than sufficient braking, i would rather go to a smaller disc than have holes drilled in them. The saving in rotational inertia is worth a buttload more than the saving in unsprung mass.
Jabberwocky
Posted: May 16 2005, 06:49 PM


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I dont want to get too deeply into it, but going with a smaller diameter usually means a small pad. Also the braking force depends partially on the velocity of the rotor relative to the pad. There are tradeoffs to everything. I'm not saying that crossdrilling is better or worse, but that it is another valid way to lowering rotational mass.

This post has been edited by Jabberwocky on May 16 2005, 06:54 PM
MidnightViper88
Posted: May 16 2005, 07:18 PM


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I like the drag racing cue of parachutes...
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Posted: May 16 2005, 07:18 PM


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so sloted rotors are better than having crossed-drilled rotors------In heavy racing i think.........
and Having Bigger rotors and Bigger Brake pads, give u better braking........

crossed-drilled rotors look nice, but are more for street/light racing........

and

i dont think having a smaller rotor and smaller pads would help u brake better.......well from what i read in the first post.......Having a bigger rotor surface, will dissipate and dispense heat faster.........

you would have less surface for heat to dissipate into the rotors and heat wont dispense as fast as a bigger one would......i think

correct me if im wrong, im still trying to figure it out, trying to make it easy for others........got to learn this stuff.....its interesting....... cool.gif
Jabberwocky
Posted: May 16 2005, 08:18 PM


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It can't be oversimplified too much. I'd just wanted to point out that crossdrill rotors arent complete junk. I use regular blanks myself because they are cheaper and work just as well.

Here's a bunch of factors to consider (generally true):
With larger diameter rotors, you have more rotational inertia, which is very bad.
With larger diameter rotors, you also generally have more mass to resist fad, good.
With larger diameter rotors, you generally have a the pad engage the rotor at a higher velocity, good.
With larger diameter rotors, you generally have the air vanes in the rotor working at a higher velocity to dissapate heat, good.
With holes/slot drilled in, you generally have less pad to rotor contact, bad.
With holes/slot drilled in, you generally have less rotational inertia, good.
With holes/slot drilled in, you generally have less mass to resist fade, bad.
With holes/slot drilled in, you generally have a weaker rotor prone to cracking, bad.
With thinner rotors, you generally have less rotational inertia, good.
With thinner rotors, you generally have less mass to resist fade, bad.
With thinner rotors, you generally have a weaker rotor prone to warping, bad.

That barely scratches the surface. Then there's the tires effect on braking, the caliper design, the brake pad material, the rotor's material, rotor vane design, antisquat and antidive and their effect on weight transfer during braking and more.

I know that I'm not that knowledgeable on brakes either. There is probably plenty of stuff that I haven't even mentioned.

For those looking for more braking power, I'll say this. The biggest factor IMO is brake pad, the difference between el cheapo autozone pads and something like HP+ is just astounding.

This post has been edited by Jabberwocky on May 16 2005, 08:33 PM
vhsfootball_82
Posted: May 16 2005, 08:36 PM


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QUOTE (Jabberwocky @ May 16 2005, 08:18 PM)
It can't be oversimplified too much. I'd just wanted to point out that crossdrill rotors arent complete junk. I use regular blanks myself because they are cheaper and work just as well.

Here's a bunch of factors to consider (generally true):
With larger diameter rotors, you have more rotational inertia, which is very bad.
With larger diameter rotors, you also generally have more mass to resist fad, good.
With larger diameter rotors, you generally have a the pad engage the rotor at a higher velocity, good.
With larger diameter rotors, you generally have the air vanes in the rotor working at a higher velocity to dissapate heat, good.
With holes/slot drilled in, you generally have less pad to rotor contact, bad.
With holes/slot drilled in, you generally have less rotational inertia, good.
With holes/slot drilled in, you generally have less mass to resist fade, bad.
With holes/slot drilled in, you generally have a weaker rotor prone to cracking, bad.
With thinner rotors, you generally have less rotational inertia, good.
With thinner rotors, you generally have less mass to resist fade, bad.
With thinner rotors, you generally have a weaker rotor prone to warping, bad.

That barely scratches the surface. Then there's the tires effect on braking, the caliper design, the brake pad material, the rotor's material, rotor vane design, antisquat and antidive and their effect on weight transfer during braking and more.

I know that I'm not that knowledgeable on brakes either. There is probably plenty of stuff that I haven't even mentioned.

For those looking for more braking power, I'll say this. The biggest factor IMO is brake pad, the difference between el cheapo autozone pads and something like HP+ is just astounding.

very true..........
autozone pads,,,,,,cheapo.......brake pads do make a difference in braking.......big time
TaksPandaHatch
Posted: Sep 10 2005, 12:26 AM


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Alright.
The bigger the rotor, the more heat you will disipate, which means less brake fade and not having to turn your rotors because of warpage.
Pads do make a difference. I heard some dumb a$$ at Kragen say that ceramic pads will stop squeeking. BS The squeeking is the brake pads moving in the caliper while braking causing a high pitch sound. Ceramic work better at a high heat range and that is why more cars are using them. While Semi Metallic pads work better at a low heat range.
Now, cross drilled rotors and slotted rotors. Prectically the same.
Cross drilled CAN disipate heat better because the air hits them, but they are taking away metal mass and brake surface area they cannot disipate heat as well because its NOT there. SO you can stop better but you can't either. YOU GAIN and lose.
Some Slotted rotors have more pad surface area, some have less,but for the most part, but you have more metal to help disipate the heat than drilled rotors.

They also BOTH help remove gasses that build up on the pad surface.
Better braking can be achieved by removing the heat, that is the goal of the rotors. You can also increase the rotor size to achieve better braking because you have more brake pad surface area.

This post has been edited by TaksPandaHatch on Sep 10 2005, 12:32 AM
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Posted: Sep 12 2005, 08:50 AM


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QUOTE
First, lets get some physics. Tell me how a heatsink with less mass will cool better?


Greater surface area.

Not neccessarily true in regards to drilled rotors where you're not getting any more surface area, but true in a general sense.

Look at the heatsink in your computer. A heavily vaned chunk of aluminum. A solid lump of aluminum would have greater mass and a better ability to absorb heat but far less ability to dissipate that heat since the air flowing over it would pass over a far smaller surface area.

I want rotors with a fractal surface. To the pads it would be just like a normal solid disk. To the air though the surface area would be simply immense. Orders of magnitude greater than the flat surface of the rotor.
Pearce
Posted: Sep 19 2005, 08:36 AM


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someone mighta said this...that's too much to read...but i heard hey warp more easier when they're crossed drilled because they heat up really hot and then cool so quickly...heard it from some street racer...not to sure on the validity of his statement, but it does kinda make since
MidnightViper88
Posted: Sep 19 2005, 03:01 PM


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QUOTE (Nd4SpdSe @ May 15 2005, 07:26 PM)
I've always wondered then, why do high-performance cars have them?

Lamborghini Murcielago
http://www.swisscarsightings.com/lamborghi...elago%20340.jpg

Porsche 911 GT3
http://images.automotive.com/cob/factory_a..._GT3_wheels.jpg

2006 Corvette
http://www.canadiandriver.com/discus/messages/1490/24053.jpg

Enzo Ferrari
http://www-personal.engin.umich.edu/~dixit...03/P1180880.jpg

It's taken quite a few months for me to ponder over this post, but sports and supercars have more than just large-ass brakes...They also have large-ass pads to go with them, large-ass wheels, and wide/sticky-ass tires, so their braking capabilities are not soley on brakes alone...
InitialE
Posted: Sep 19 2005, 03:17 PM


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Tire compound/size are more or just as important as brakes when it comes to stopping power, it's the only thing that touches the road surface
sideways
Posted: Sep 19 2005, 03:25 PM


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Exotics drill their rotors for one reason. It looks nice, how often do u think those owners are REALLY pushing those cars aroudn tracks? (granted some of them actually DO). That and then of course they dont use the same material to make their rotors.

Wheels84ss
Posted: Sep 21 2005, 06:22 PM


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QUOTE (Nd4SpdSe @ May 15 2005, 10:26 PM)
I've always wondered then, why do high-performance cars have them?

Lamborghini Murcielago
http://www.swisscarsightings.com/lamborghi...elago%20340.jpg

Porsche 911 GT3
http://images.automotive.com/cob/factory_a..._GT3_wheels.jpg

2006 Corvette
http://www.canadiandriver.com/discus/messages/1490/24053.jpg

Enzo Ferrari
http://www-personal.engin.umich.edu/~dixit...03/P1180880.jpg

Unfortunately anti-rice is down so i can't get the link to the actual reason because we did one of these threads a while ago... But it was explained something like this....

The exotics use crossdrilled for astetics and less rotational mass.... Usually exotic setups have more braking capacity then is actually required for the vehicle.... So you can crossdrill the rotors to lighten the load and appeal to the eye without actually decreasing the max braking the car can do... (because the system itself far surpasses what the tires and the suspension will allow)

So short answer, it looks cool....
Nd4SpdSe
Posted: Sep 23 2005, 05:09 AM


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Well, I've been runing Brembo Cross-Drilled and Slotted with PBR ULX Ceramic pads. I kept the Dot3 Fluid (cause I would need to change all the parts to make sure the system is clean) and want with new steel lines, although I wanted to get stainless steel/teflon braided lines, a miscommunication between me and the guy ordering the lines would have put them beyond my available timeframe, fortunately I found out that they are not DOT approved in Canada, so I don't feel do bad

Although I can&!39;t give a blank rotor vs XD/S rotor comparison because of the upgrades in pads, I will say that the combo I'm working with is amazing and hasn't decreased in the several months I've ran them. It's neat, me and a friend were driving about on the highway and were playing around, I was behind him and he saw a cop way up ahead and slammed on the brakes. Now, I don't slam on them cause I know they would lock up, but I was pretty hard on them and not only did it feel like my heart was going to come out of my chest, but it almost felt like my rear wheels wanted to come off the ground.

We did some touge "crusing" with the Rx-7 club in spring and they performed great, even when my rear wheels were 2" off the ground (literally, as the Rx-8 driver behind me witnessed). I can't wait until next year biggrin.gif

I did a tune up and I was checking the rotors, they are acually worn in about 1-2mm, so there's some good friction going on, and I can't see the XD/S rotors being anything but beneficial at this point. I know last time I went on the Rx-7 cruise, that my rotors literally burned blue from overheating, how, my car, although it didn't have as much power, it didn't handle as well either do I was doing more braking, but even this year, it wasn't a walk-in-the-park either, although I'm happy that I kept up with the Turbo FD's no problem biggrin.gif And they were really impressed as well. My setup was only a few days old at the time, but next year, I'll push her alot more, I'll show them what my Mx-3 truely can do biggrin.gif
sideways
Posted: Sep 23 2005, 06:36 AM


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Braided lines often dont pass dot approval because they rarely pass the "spin" test (which has jack to do with braking anyways- so who gives a crap)
Batmanbeyon
Posted: Sep 28 2005, 10:55 PM


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i recomend the SS lines they will make the pedal more stiff and under extreme preasure they wont blow unlike the fatory lines.

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