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10-21-2007, 05:41 PM | #111 | |
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+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! |
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10-21-2007, 06:15 PM | #112 | |
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If the response time between the driver input and the flow input to the engine is shortened, the driver would naturally have more control over what the engine is doing, and can use that to his/her advantage--depending on the driving scenario I guess. |
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10-21-2007, 06:44 PM | #113 | |
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Greg Lake Oswego, Oregon, USA 2023 M2 Coupe - Brooklyn Grey/Cognac/CF, 6MT; 2020 MB GLE 450 |
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10-21-2007, 07:04 PM | #114 | |
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"Increasing the size of the pads will not increase clamping force." The area over which the clamping force is applied is moot in terms of stopping power; larger "swept area" will only increas pad life, as each sq. cm. of pad is doing less work. The second most improtant area is the rotor size; larger rotors offer a greater heat sink and area with which to dissapate heat, and greater moment arm for reverse torque application.
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Greg Lake Oswego, Oregon, USA 2023 M2 Coupe - Brooklyn Grey/Cognac/CF, 6MT; 2020 MB GLE 450 Last edited by GregW / Oregon; 10-21-2007 at 10:45 PM.. |
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10-21-2007, 07:36 PM | #115 | |
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Sure, I would agree, however, I am not so sure that the M3's large single piston has more stopping "area" than Porsche's multi-piston caliper. Without going back and checking the rotor sizes on each car, I'd have to guess -from memory- that the rotors are very close in size. Larger rotors do increase heat sink as does the type of material used, the method by which they are made and the ventilated efficiency. The part about an increase in pad size only increasing pad life applies to enlarging a pad without equally enlarging the forces behind it; i.e. more pistons and/or larger ones, which would create more pressure per sq. cm. |
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10-21-2007, 08:17 PM | #116 | |
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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. |
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10-21-2007, 08:42 PM | #117 | |
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Very informative, but do you find it necessary to accuse me of prejudice? Speculation, sure. Pride, maybe, we're all guilty of that time to time. As much as it's expected of Porsche to have stellar brakes, it's equally expected of BMW to have less than stellar brakes. |
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10-21-2007, 10:14 PM | #118 | |
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