spiroh

Yesterday, I was driving aggressive. I get out of the car, because I smell something really bad. I look, and I see my rotors were cherry red!!!

Spiro

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Black/Black 2001 CL-S
Random Technology Cat
RED AEM CAI
APEXi V-AFC
Polarg M6 Roadlamps

fender4

sounds like a very personel problem, might bring this up at a different type of board.

SidVicious

Hmmm... what did you do about it? Is there any change in braking since then?

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SidVicious
2001 CL Type S w/ NAV in Silver | Wheel Locks | Front Plate (Mounted in the Trunk) | Mobil 1 | Polarg M6 | K&N Filter (Installed 6/19/01) | Comptech Sways (waiting to be installed) | Sungard Tint (30% Sides, 20% Back) | DOM 11/2000 |

1992 Ford Ranger XLT in Silver | F-150 Springs | 3" Body Lift | K&N Filter | Flowmaster Exhaust |

{insert "Green Box 4 Mod!" gif here}

spiroh

None that I have noticed. Just seems odd they would be that hot.

Spiro

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Black/Black 2001 CL-S
Comptech Headers
Random Technology Cat
RED AEM CAI
APEXi V-AFC
Polarg M6 Roadlamps

so cal type s_RENAMED

time for some slotted rotors. .

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LAKERS: BACK TO BACK!

Iridium130

Did you touch them? I wonder how hot they were...

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_-Phil-_! (a.k.a. 'Green Box')
2K1 #10,029 Satin Silver CL-S since 6/13/00 named Laetitia with Navi! Mods : XEPHYR PERFORMANCE CAI~3M Reflective Tint(37%) tint~Hiper Hibrid Plasma "Xenon" road lamps & high-beams~Uniden LRD 6599SWS Radar Detector~Shine by Meguiar's Gold Wax~Member of the Scratched Rims Club~Upgraded cupholder ~

http://www.postwhores.com

spiroh

So my finger can melt! =) They were red man.



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Black/Black 2001 CL-S
Comptech Headers
Random Technology Cat
RED AEM CAI
APEXi V-AFC
Polarg M6 Roadlamps

Chris

time for some cross drilled rotors...

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Acura 3.2CL Type-S w/ Navigation
Black/Ebony

H&R Sport Springs | Pirelli P7000 Supersport 235/40ZR17 on stock rims | Neuspeed Tower Strut Bar | Custom CAI | Cleared Headlights, PIAA 19169 | Tint all around | Mesh Grill | Dual 12'' Alpine Type-S Subs | Kenwood KAC-728S Amp | RÄZO real carbon pedals

Dan

Pigs fly! News at 11!

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You can never have too much horsepower!

DtEW

Time for another explanation...

Cross-drilled rotors do not aid much (if at all) in dissipating the heat of the rotor. In fact, they reduce the total braking surface of the rotor, which generates more heat-per-area for the same amount of braking.

OTOH, hot rotors in themselves are not the cause of decreased braking performance. Brake fade falls into two categories: fluid fade and pad fade. Slotted/cross-drilled rotors primarily address the latter.

When brake pads reach very high temperatures, it generates vapors (the fried-brake odor) that act like a cushion/lubricant against the brake rotor in much the way an air hockey table generates it's own layer of cushion/lubricant under the puck.

The slotted/cross-drilled rotors vent these vapors, vastly reducing the cushion/lubricant effect.

If you want cooler rotors (and relatedly, cooler pads and fluids) for the same amount of braking, you'll need bigger rotors and pads.

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051/LP/SR/LD/HH
Potenza S-02 Pole Position

The Reasonable Voice of Bias

[This message has been edited by DtEW (edited 06-20-2001).]

Technique

ROFLMAO!!!!!!!!!!

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Silver CL-S w/ Navi, Spoiler, Wheel Locks, Trunk Tray, 19169, 9005
Toyo 235/45ZR17-97W* T1-S Proxes on 17X8 SSR Competition Wheels (47.2 lbs lighter than stock wheel+tire setup)
Comptech Sways
G-Tech (Full tank of gas, 60F, VSA off, SS) - 5.94 seconds
V-1 Hardwired

EricL

Your explanation is very good. It is unfortunate that the entire subject of heat transfer, heat conduction, bulk heat storage properties of materials, and issues related to heat are not well explained and discussed for auto enthusiasts.

The rotors work to convert to kinetic energy of movement into "heat" via friction between the rotors and the pads. The addition of holes (as you said) does reduce the friction area and the "amount of material to soak up the heat." However, there are three ways for the heat to get transferred away from this HOT rotor:

1. Convection (air flowing across the rotor) -- and holes in the rotors expose more of the disk to the air at the expense of lost "bulk heat sinking" and "friction area".

2. Conduction -- each surface in contact with the rotor and hub will conduct heat away from this hot rotor. e.g., good wheels can make a big difference in the amount of heat that can get transferred; Aluminum is a very good conductor of heat, and most wheels are made from Aluminum.

3. Radiation -- the hotter the disk glows, the more heat is transfers to the air and surrounding parts. The bigger the difference between the rotor and the surrounding areas, the more heat is transferred (4th power relationship is involved in radiant heating).

There is just NOT an easy answer on how to cool down brakes -- it all depends on how fast the rotor can get RID of the heat vs. how fast the heat gets put into the system.

So, if I put a huge duct in the front of the car and add duct this air into the front of the rotor, and add holes and slots to the rotor, there is a point where the holes will help to transfer enough heat away from the rotor to help stopping power. The pads and fluid (as you stated) only work across a limited low-to-hot temp range, and anything that keeps this rotors in this range will help the existing pads and fluid do their job (and keep from fading).


So, to expand on the number of ways to reduce the heat buildup in our car:

1. Increase the useful range of temps that the pads work over -- CHANGE THE PADS!

2. Increase the boiling point of the brake fluid with a better brake fluid (Motul, ATE, etc).

3. Add slotting to allow out-gassing of the pads to increase conduction between the pads and rotors.

4. Add cross drilled holes IF and ONLY IF there is enough air flowing across the rotors to offset the lost material that was being used to "store the heat" -- remember an object that stores a lot of heat, also takes a while to dissipate that heat. They use carbon pads on F1 cars, and carbon has very low bulk thermal storage and conduction properties -- it heats up fast, and cools down fast too.

5. Regarding item 4 -- add air ducts or wheels with more open space to allow better air flow to the disks.



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Silver 2001 CL-S with NAVI

• Toyo T1S 235/45ZR17-97W* Proxies on 17x8" SSR Competition wheels (50 lbs less than stock)
• Comptech headers & sways
• Silver AEM CAI
• 12 coats of Zaino magic
• Stainless Brake lines coming (Brembos?)
• V1 planned

Beach-CL

Dtew and EricL:

Good job with those explanations!

Great to hear that kind of talk around here.

As someone who has done road racing at different levels, one is always looking for ways to improve braking.

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2001 Silver CL-S

so cal type s_RENAMED

good stuff. .

have you guys seen the dimpled rotors? opinions? comments?

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LAKERS: BACK TO BACK!

EricL

They couldn't hurt! I would think they would help the pads (as do the slots).

BTW--I'm still trying to find the name of any people that carry "Powerstop" rotors for our car. The story goes that they make their own rotors instead of using the OEMs and cad plating.



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Silver 2001 CL-S with NAVI

• Toyo T1S 235/45ZR17-97W* Proxies on 17x8" SSR Competition wheels (50 lbs less than stock)
• Comptech headers & sways
• Silver AEM CAI
• 12 coats of Zaino magic
• Stainless Brake lines coming (Brembos?)
• V1 planned

so cal type s_RENAMED

are you interested in the aem brake kit? stage one is just the 12" slotted rotors.

oops. the kit is not available for our car.


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LAKERS: BACK TO BACK!

[This message has been edited by so cal type s (edited 06-21-2001).]