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Old 12-23-2012, 01:25 AM   #506
JRCrutc
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Member#: 309978
Join Date: Feb 2012
Chapter/Region: NWIC
Location: Vancouver Wa/Portland, Or
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2012 WRX hatch
Ice Silver Metallic

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Quote:
Originally Posted by prncnhorse View Post
I didn't read anything in the otherwise brilliant post about ABS brakes. We aren't talking about systems that lock up so there might still be something to the increased surface areas of larger rotors.

But, with that said, I once made a full pass in an 11 second Chevy II with original drum brakes on all 4 corners. Very Scary and dodgy but I didn't die!
From what I understand of the subject, the abs system is actually modulating the brakes so that the wheels don't lock. They do this because the braking distance of a rotating tire is lower than that of a sliding tire. This actually doesn't factor into the question of brake capability much though, mainly because it is trying to account for the different coefficients of friction (static, as in the rotational situation, and kinetic in the sliding situation).

The system that we are discussing doesn't include the tire and road interface. The brakes locking are an ideal condition for a system where an idealized rotational mass is being studied. In this situation the important forces involved are between the disk and the brake pad. The force equations here are actually less dependent on brake pad contact area than they are on brake pad material. Which would indicate that as long as the stock brakes are using a sufficient material they should do the same job (on the first stop) as the more expensive brakes. They will be much less fade resistant than better brakes because of the geometry of the brake interface, but that is another story.

There are just too many variables to account for if you look at the whole system while simply comparing brake capability. ABS actually plays an important role in stopping the car, but it doesn't factor into the comparison of actual brakes.
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