Blue Hybrid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">No. You are not going to have nuclear fission in your brakes. Ever.</TD></TR></TABLE>

lol, i didnt say that, but you agree that the gasses need to be removed to cool the brakes, and the heat is caused by the molecular vibration of the gas.

but how cool would that be, evertime i see someone i dont like, i brake real hard, and kaboom! theyre vaporized

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">
No. Removing heat with air is convection. There are other kinds of energy transfer, like conduction (through the rotor surface itself, through the caliper, etc) and radiation. </TD></TR></TABLE>

yeah convection is the transfer of heat from a solid to a gas therefore, still requiring a gas. conduction is only within the matter itself, it never transfers, so the heat is never dissipated

drdisco69

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gold EF &raquo;</TD></TR><TR><TD CLASS="quote">yeah convection is the transfer of heat from a solid to a gas therefore, still requiring a gas</TD></TR></TABLE>

Yes, that's true. But that's not how heat is transferred from the pad to the rotor. It is transferred through conduction, because they are touching. No air/liquid/anything is required.

It is true that heat is the molecular vibrations of atoms, and that with sufficient heat, you can experience a phase change from solid to liquid, and liquid to gas. But the pad must reach it's melting point through the absorption of thermal energy from the transfer of kinetic energy to thermal energy that the brakes perform. Just having "vibrating gas molecules" next to the pad doesn't mean it's going to melt. The bottom line is that whatever you want to melt the pad with has to be above the melting point of the pad, and have enough energy to transfer to the pad to perform that melting without falling below that melting point right away.

I sense a small review of thermodynamics is in order.

Blue Hybrid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">Yes, that's true. But that's not how heat is transferred from the pad to the rotor. It is transferred through conduction, because they are touching. No air/liquid/anything is required.</TD></TR></TABLE>

the heat isnt in the pad, its in the rotor and the pad. you want to get the heat away from both, and even if the heat is transfered to the pad, if it never dissipates, it will continuously heat the pad forever

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">Just having "vibrating gas molecules" next to the pad doesn't mean it's going to melt</TD></TR></TABLE>

i didnt say that the melting pad is caused by vibrating gas molecules... i said that the energy or heat that is causing the molecules needs to be removed

all im trying to say is, drilled rotors dissipate heat better because it has more surface area and more places for gasses to escape

i give up

who needs the review in thermal dynamics? i know it aint me

drdisco69

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gold EF &raquo;</TD></TR><TR><TD CLASS="quote">i didnt say that the melting pad is caused by vibrating gas molecules</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gold EF &raquo;</TD></TR><TR><TD CLASS="quote">the molecular vibrations in heated oxygen are enuf to melt the brake pad.</TD></TR></TABLE>

Oh.

Like I always say, I don't make this **** up.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gold EF &raquo;</TD></TR><TR><TD CLASS="quote">all im trying to say is, drilled rotors dissipate heat better because it has more surface area and more places for gasses to escape</TD></TR></TABLE>

I never argued that. It's obvious that it's true. It's not the question, the question is if crossdrilled rotors are better. There is more than one consideration when it comes to making that decision, and heat dissipation is only one.

Blue Hybrid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">
I never argued that. It's obvious that it's true. It's not the question, the question is if crossdrilled rotors are better. There is more than one consideration when it comes to making that decision, and heat dissipation is only one.</TD></TR></TABLE>

yes but what began our discussion was whether or not the holes in drilled rotors trapped heat.

do you notice we are the only 2 dumbasses on here

drdisco69

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gold EF &raquo;</TD></TR><TR><TD CLASS="quote">do you notice we are the only 2 dumbasses on here </TD></TR></TABLE>

Friday night and all we can do is argue about thermodynamics. We're cool.

Blue Hybrid

i should call you up next time in nc, maybe you can show me where the ricers go cause last time i was there, all i saw was trees

Blue Hybrid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote"> Friday night and all we can do is argue about thermodynamics. We're cool.</TD></TR></TABLE>

discuss, not argue, discuss haha

drdisco69

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gold EF &raquo;</TD></TR><TR><TD CLASS="quote">i should call you up next time in nc, maybe you can show me where the ricers go cause last time i was there, all i saw was trees</TD></TR></TABLE>

Ricers go to hell! And you're right, there's a poopload of trees where there should be more racetracks.

We have kept it pretty civic, actually. Discuss is a better word.

Redline96LX

To regard the issue of expanding gas.

Ok, suppose a tiny air bubble got between the pad and rotor. Now your car is going like 60mph, so the rotor is making a full rotation many times per second. The brake pad covers maybe 1/6 of the surface area of the contact area between rotor/pad. A tiny air bubble gets between the rotor and pad, and heat is added, so it wants to expand. The air bubble, very tiny, would be out of the pad so fast, and theres also that line in the brake pad (if you get anything half decent). That tiny possibility of air heating isnt gonna really affect anything, its not even an issue. But...if you had drilled rotors, well there are still parts between the rotor and pad that do not use the holes, so unless your holes would touch ALL of the brake pad, that idea is shot to ****. And if you want to get picky about the possiblity of introducing air in that tiny crack between the pad and rotor, the holes could also encourage this, as would slots.

Sorry If I'm not explaining this well enough, but gassing with modern brakes....just isnt an issue. Even F1 cars with ceramic brakes dont use holes or slots....and those brakes get RED hot!

Squelch

sometimes its more fun to learn things in h-t than in sch

theleftis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by factorviii &raquo;</TD></TR><TR><TD CLASS="quote">sometimes its more fun to learn things in h-t than in sch</TD></TR></TABLE> LOL, i'm still waiting for the continuation

Redline96LX

is there anything else you want me to say or teach you?

CoffeeBurner

Not saying I'm for or against drilled/slotted rotors, but I am pretty sure that I've never seen a rotor with any closed voids where gas could build up and cause problems. That aside I always assumed that they were slotted/drilled for heat dissipation... more surface area = better dissipation. If ya dont believe that... break all the veins off of your computers CPU heat sink or replace it with a plain block of metal and play some games... surface area good

Redline96LX

Sir, I understand what you mean, consider a 1" tube, then a small intestines, SO much more surface area. But those little holes, the surface area....i mean a bit more but when you do the math, it just isnt as good. You have the theory correct, but if you calculate the loss in surface area, and the gain from that little extra surface area, its negligable for cooling, and a lot worse for braking distances.


Modified by Redline96LX at 11:15 PM 2/7/2006

drdisco69

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Redline96LX &raquo;</TD></TR><TR><TD CLASS="quote">is there anything else you want me to say or teach you? </TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Redline96LX &raquo;</TD></TR><TR><TD CLASS="quote">if you calculate the loss in surface area, and the gain from that little extra surface area</TD></TR></TABLE>

Are you sure you're the right person to be teaching us?

Repeat after me: "Surface area of the pad doesn't matter. Friction force is independent of the surface area." Don't you feel smarter now?

Redline96LX

Shut up man you know what I mean.

The increase of surface area of the entire rotor may increase with the holes, but not by much, the vents do much more for cooling, and with the less surface area for the pad reduces the heat transfer from the pad to the rotor, the rotor being the main heatsink.

The holes and slots increase the surface area of the rotor, but not by that much, and it doesn't make a big enough or noticable difference, whereas the LOSS of area where the friction is made makes a larger difference.

De_tour

I was going to buy cross drilled rotors for my civic but i decided not to after asking a tooler at boeing about the drilling that most companies apply to the rotors.

This is the closest article that i could find that explains it best from what was explained to me.

Residual stresses are present in most materials as a result of thermal and mechanical loads applied during fabrication. For example metals are "forged" into a desired shape with large loads at high temperatures. But when the fabrication loads are removed and the outside surface is cooled faster at the surface, larger thermal contractions occur at the surface compared to the interior. Micro-structures are also different at the surface and upon further cooling stresses are frozen even after loads are removed. Hence the name residual stress. A similar process occurs in the formation of welds. Often these stresses are unknown but sufficiently large such that cracks initiate and grow causing unexpected failure. It is common practice to remove these "as-welded" residual stresses by "post heat treatment". In some cases residual stress can be controlled for a desired beneficial result, e.g. residual stresses are intentionally created in tempered glass where compressive stresses are created near the surface that prevents crack growth and raises the fracture strength. Residual stresses are associated with space gradients, e.g. again in tempered glass compressive stresses near the surface change to tension below the surface. Residual stress gradients are important in understanding and predicting matertial response

Heres the link for the rest of the article
http://www.sv.vt.edu/future/vt....html


So in the end, i didnt want to pay out that much money on post heat treated rotors.

STICK WITH OEM!

JDMs1eeper

Brembo Blanks + AXXIS Metalmaster pads here

Sic_DA_Nine

anyone have any input on kragen rotors....to be more precise, RAYBESTO

i was looking into slotted but the information given has got me to change my mind

HT Chaplain

all high performance motorcycles use drilled rotors so there must be something to it because braking for them is extremly important ,and nothing stops quicker than a sportbike
BTW i never seen a cracked rotor on a sportbike maybe because they are lighte than cars?

drdisco69

Bike rotors are "drilled" for weight, and they have enough brakes and so little weight that they don't get the brakes as hot. The rotors are also in open air, and I'm willing to be the holes are cast in, not drilled.

IGGY

Umm, F1 doesn't us slotted rotors?

http://www.atspeedimages.com/p...s.jpg

Those are metal transaxle brakes with slots, they don't use slots in the front because they are composit.

midniteweezer

Wanna go find out the age of that car? In the title of the link i see the word "historics" and the number "1972". Still, if you want to go do the actual math, slots and holes are not as good as blanks. Not saying your wrong, but 30 years ago is considered outdated.


Modified by midniteweezer at 8:03 PM 3/3/2006

IGGY

Your right all modern F1 and Indy cars use carbon pads.

Here is a shot of 2004 JGTC Mugen NSX.



I guess slots are bad.