Cobra vs. Bullit vs. Stock GT brakes, are they worth it? lets find out.
#62
wrong. You're rotors are rotating at exactly the same RPM as your tires. The linear distance traveled by your brake pads over the rotor is DRAMATICALLY lower than the distance your tires have covered.
#65
You're partially incorrect: it's actually a higher rotor speed if you're measuring linear velocity. If you're measuring angular velocity it's exactly the same.
The larger surface area and higher linear velocity of the larger diameter rotor creates greater friction across a friction pad of similar area using a caliper of similar clamping force capacity by exposing a greater surface area to the friction pad in the same amount of time at a given wheel speed than a 10.8" GT brake setup. In short, bigger rotor is better pretty much regardless. And I 100% do not agree with them as a race item. There are 4 and 6 pot calipers for 14" rotors for real racing. The cobra brake kit is what I'd call a minimum for reliable stopping of as powerful a machine as ford puts into the hands of total motards.
Pads and rotors are slightly more expensive but stopping that extra 30ft sooner sometimes is important. It's like carrying a pistol or a pocket knife or a hanky, you're better to have it and not need it than to need it and not have it.
The larger surface area and higher linear velocity of the larger diameter rotor creates greater friction across a friction pad of similar area using a caliper of similar clamping force capacity by exposing a greater surface area to the friction pad in the same amount of time at a given wheel speed than a 10.8" GT brake setup. In short, bigger rotor is better pretty much regardless. And I 100% do not agree with them as a race item. There are 4 and 6 pot calipers for 14" rotors for real racing. The cobra brake kit is what I'd call a minimum for reliable stopping of as powerful a machine as ford puts into the hands of total motards.
Pads and rotors are slightly more expensive but stopping that extra 30ft sooner sometimes is important. It's like carrying a pistol or a pocket knife or a hanky, you're better to have it and not need it than to need it and not have it.
I was using linear velocity to prove that larger disc brakes require less work to stop/slow down. Like if you use UDP as a point of reference, the bigger the gear is the lower your rpm's will be and less power will get to the rear.. get a smaller pulley gear for it and you will get higher rpm's faster. the point I'm trying to make here is that the bigger the disc the slower it will be moving at it's edge where the caliper is and the easier it will be to stop.
if you want to test this buy 2x different size rotors and pop your wheels off, get a scientific strobe light and rev it up. I guarantee the smaller ones will have a faster rpm (make sure they are drilled or slotted so you can actually tell what rpms with the strobe)
maybe I'm muddling up my math somehow I don't know, it's been awhile since I've been in any math class and I have never really needed that sh** until I read this thread lol oh well
but yeah, 14" with 4piston calipers FTW (unless you drive like old granny, then you might want the honda civic downgrade.. stop too fast and you might give yourself an anuerism)
#66
The GTR does not have 19" rotors.
#67
19" rotors would be retardedly heavy and BAD for handling. It has 19" wheels for sure as, IIRC, the GTR has a 15" 2-piece rotor and a set of cast Brembo monoblock 6 pot calipers in front. It's a nice track day brake setup but not for true racing, and don't get me started on cross drilled rotors from the factory... even they do stupid **** sometimes.
I have no idea how they can justify a 15" brake kit for a street car though. All it does is drive the cost of ownership through the damned roof. Imagine the cost of 2 piece 15" rotors, my 13" Baer thick cheek eradispeeds were almost 300 each, so pricey that I don't use them outside of a track environment anymore.
I have no idea how they can justify a 15" brake kit for a street car though. All it does is drive the cost of ownership through the damned roof. Imagine the cost of 2 piece 15" rotors, my 13" Baer thick cheek eradispeeds were almost 300 each, so pricey that I don't use them outside of a track environment anymore.
#68
19" rotors would be retardedly heavy and BAD for handling. It has 19" wheels for sure as, IIRC, the GTR has a 15" 2-piece rotor and a set of cast Brembo monoblock 6 pot calipers in front. It's a nice track day brake setup but not for true racing, and don't get me started on cross drilled rotors from the factory... even they do stupid **** sometimes.
I have no idea how they can justify a 15" brake kit for a street car though. All it does is drive the cost of ownership through the damned roof. Imagine the cost of 2 piece 15" rotors, my 13" Baer thick cheek eradispeeds were almost 300 each, so pricey that I don't use them outside of a track environment anymore.
I have no idea how they can justify a 15" brake kit for a street car though. All it does is drive the cost of ownership through the damned roof. Imagine the cost of 2 piece 15" rotors, my 13" Baer thick cheek eradispeeds were almost 300 each, so pricey that I don't use them outside of a track environment anymore.
#70
It happens. Just don't let it happen again. haha
#72
Yes you would assume so since you are likely what 300lbs lighter or more? Not sure what the 02 GT's weigh; plus you have alot less weight on the nose of your car than I do on my 03 cobra.
Let's face it, it's a fun car for the highway, but you generally don't make a competitive race car by adding weight, hence the V6. Smaller engine, less weight up front. smaller brakes (less weight), stick axle, manual trans, etc.
#73
You don't nomally correct oversteer (loose) by adding cornering stiffness to the front, you do it by putting on a weaker sway bar (or springs in extreme cases) in the rear. If you're trying to decrease understeer or plow in the front (push) then you can put in a little more negative camber, positive caster and add front sway strength (you can also put a little toe-out in the front end to make it turn snappier). If you're trying to make the car looser you can add spring to the back.
GT brakes are perfect for most street driven v6's but GT's are seriously under-equipped with stock brakes. With the right pads they're good for autox. Longer events would be hard on rotors.
GT brakes are perfect for most street driven v6's but GT's are seriously under-equipped with stock brakes. With the right pads they're good for autox. Longer events would be hard on rotors.
#74
I do open track events and nothing is scarier than looking at a 25 mph 90 degree left hand corner and feeling the brake pedal just sink all the way to the floor while the speedo slowly oozes south of 80mph. Downshifting into 2nd and awesome tires saved the day, but bigger brakes have been near the top of my list of things to do for a long time. Good post
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Mirage775
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02-22-2007 07:16 PM