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      10-21-2007, 08:17 PM   #116
swamp2
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Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

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Obviosuly, you are wrong

Quote:
Originally Posted by devo View Post
Swamp, obviously, the previous post regarding the color of the brakes was directed at Porsche, so I have to chime in. Feel free to lambaste me at will. I am accustomed to it. However, facts are facts.

+1 to the aforementioned post. More force over more of a swept area, making multi-piston brakes more effective than single piston ones. Everything else being equal, of course.

So, whether the rigid four and six piston "red" brakes on a Porsche offer "more" clamping force is moot. It is that they offer more clamping force over a broader area. Which is why BMW's brakes -in their current configuation- will not compete with Posche's over repeated hot stops. No matter how much road test data someone finds where the M3 bests the 911 in a single contest.

Whether or not better brakes are needed for the street has yet to be determined, however.

Great info, by the way!
You are completely incorrect in your assumption that my comments about caliper color was directed at Porsche. Since I have not spent enough time on this BMW forum complimenting Porsche (sarcasm…) I will make the record clear here. Porsche makes (buys actually) absolutely top notch brake systems including performance, fade and looks. I would be thrilled if BMW chose brakes as nice at Porsche for its M cars. Just FYI my color comment was directed at folks that believe multi-piston set ups (which just most often happen to be red and pretty) means definitively that the brakes are better. As I stated, rotor diameter, caliper size, rotor design and brake cooling are all more important than the number of pistons.

Your “conclusion” about Porsche brakes besting the E92 M3 brakes in fade performance is highly speculative. Until a test has been done that is all it is - speculation. I do agree that it is likely that the 997S will best the M3 by a bit in extreme fade performance given the negatives we have heard thus far about the M3 brakes and what we know about the reputation of Porsche brakes. However, a test is a test and data is data. All you have now is pride, prejudice and speculation.

Last the average pad diameter is more important to brake torque than pad or piston area, you need brake torque to decelerate, torque = force x radius and the radius is not the rotor radius but the average radius of the pad contact patch. Of course typically the average pad radius scales exactly linearly with rotor radius. Although it is certain that larger radius gives more torque it is not certain that more pistons = more force.

Sizes:
997S Front Rear (dia x width) (inches)
13.0 x 1.34 12.0 x 1.10
E92 M3
14.2 x 1.18 13.8 x .94

No big surprises here, the M3 is heavier and needs larger brakes to bring equivalent performance.