I didnt say I race and am a professional drag racer, I just drive a little harder than normal, I didnt expect vibration in my steering while braking with such big rotors. My cousin has an 03 M3, and drives it the same as I do, and never had rotor issues. The g37 is a sports car, its designed to do this, thats why it has bigger rotors. If it were a honda civic, I would understand.

 

M3s have more aggressive pads than the G. Maybe that is the solution to your problem.

Ask your cousin how much his brake pads dust compared to yours

 

Just clear the air a bit. I have just over 2000 miles and i no longer feel a vibration. actually i havent for the last several hundred miles maybe a thousand miles. maybe they needed to be "broken in" if that even exists with brakes. im not an expert so. once in a while i feel a slight vibration but now im dropped with 20's and rubberbands so im guessing its road vibration.

 

yes, i did overlook something. you drive over crappy roads. theres your vibration.

 

^^ Well in in long island so its not as bad as the boroughs. i will say driving the belt pkwy is absolutely F'ing brutal. those bridges kill me. i slow down to about 40mph. people get pissed but i dont give a shizz.

 

What do pads have to do with the rotors warping? These are stock pads on a stock rotor. My rotor surface is not level, hence when I hit my brakes, the steering vibrates. Once the rotors are turned, the surface is smooth again, provided there is enough material left. Once the heating/uneven cooling cycle happens again, they rewarp. Its a problem in the rotors. I dont know why there is so much confusion here, many people have this problem, similarily they also are troubled with squeeky brakes in reverse, throwout bearing noise etc.

 

Warping means your rotors are wavy, and the structure has been irreversibly damaged. Turning the rotors DOES NOT MAKE IT GO AWAY. heating/cooling doesnt "rewarp" the rotors, since turning the rotors doesn't 'unwarp' them.

I think you don't understand the concept of warped rotors.

Think of it this way. If a piece of paper gets wet, and then dries, it gets wavy. This is like warping a rotor. Can you ever make it straight again? No. You can re-wet it, and iron it out, and it will never be straight again.

As I said before, all it takes is a SINGLE 60-0 stop at full ABS to take the OEM pads beyond their limit. Overheated pads lose their consistancy, and leave deposits, and possibly crumble.

Read what I said. If you do extended hard braking, get higher temperature brake pads. I would suggest that you learn to cool your brakes properly but I don't think that is an option here.


I'd like to ask you a question to gauge your understanding of brakes. Please explain to me how a brake rotor and pad function together to reduce vehicle speed.


Oh, and to answer your question, pads have EVERYTHING to do with warping. Without the pad, warping cannot happen.

 

I dont know, brakes in a nutshell are kinetic energy converted to heat, plain and simple. hydraulic fluid is channeled through a caliper which compresses a piston which presses a metallic/ceramic/whatever they make now into a metal disc resulting in heat production.

when your brakes are applied hard, the speed and weight of your vehicle and converted to heat, now the rotor can heat evenly, which usually does occur and your car slows down. but for instance, if a water puddle is hit it can possibly unevenly cool the rotor, similar to a hot frying pan being dipped into water halfway. one side cools faster then the other, resulting in a deformed surface.

If the SURFACE of the rotor is not even, machining them down a few mm via a special machine which grinds down the surface will return that same smooth surface so symptoms such as vibration in the wheel will not be felt. The reason you feel vibration because the rotor surface isnt smooth, and when you compress an uneven surfaced disc at higher speeds it will vibrate.

And by the way, paper and metal are totally different in terms of physical property.

You seem to be stuck on the pad crumbling/deformation idea. Yeah if you auto X your car no doubt better rotrs and pads would be needed. One full stop from 60 is not enough to warp rotors on a sports car. Because if that was the case, ALOT more people would go to the dealer for any car to get new rotors and pads everytime the brakes were pressed.

I don't understand the confusion here. My rotors are warped, if you feel so inclined, I'll pull my wheel off, get a vernier caliper and show you the difference along the rotor as well as showing you my pad condition. sheesh.

 

The very fact that turning the rotors solved your problem is proof that the rotor is not warped. If the rotor was warped, then both the outer and inner surfaces of the rotor would be uneven. If only the outer surfaces were machined flat, the inner surfaces are still uneven, and would manifest itself with the same symptoms.

The rotor itself is a surface for brake pad material to deposit itself. During bed-in, a layer of transfer film about a few microns thick will form on the rotor surface. Shearing of this film via friction is the source of braking. Common conception is that the pad is simply pressed onto the brake rotor, and the rotor itself causes the friction for stopping. In reality, that would only cause cutting, plowing, or scoring. This is why when your brake pad is gone, you have minimal, if any braking ability.

If you do a high-speed stop, then the brake pad comes to a rest on the rotor. This causes an abnormal amount of pad materiel to deposit itself onto the rotor, and your transfer film is now uneven. This is your "warping". Machining/turning the rotor flattens the surface of the rotor, taking this uneven deposit along with it.

One full stop from 60 at full ABS will cause your brake pads to overheat. That funky smell you get is the first indicator that your pads are overheated and that you should not stay at rest.

This is a reason why race cars do a cool down lap.


Going back to your puddle, when you run one over, water is pushed away from the rotor, not towards it. Drops of water on the rotor will not warp it, just how drops of water on a frying pan will not warp it. Submerging a rotor in water will warp it, but I don't drive that fast and definitely don't brake that hard if it was raining hard enough to have that much standing water around. Why would you come to a stop in a puddle that deep anyways?

 

Well like I said the turning caused a temporary fix, the problem soon returned after a few months. deposits from being stopped, possible, but I dont think this is being cause by deposits or glazing or whatever. I dont know if you can term it be be called warping or something else,

to restate, i feel my rotor surface is not even, and turning smooths out both sides doesnt it? a temporary fix, but to ultimately fix, they need be replaced right?

 

They do need to eventually be replaced.

The G37 disk is vented, meaning its really two disks sandwiched together, with a layer in between (for additional cooling). A warped disk will exhibit warping on the inner edges, meaning the disk is actually wavy, and the structure is destroyed. A deep heat cycle will probably crack the rotor. Turning a warped rotor only decreases the heat capacity, promotes uneven heating/cooling, and serves to accelerate the demise of that rotor.

I've cracked rotors, heard them pop, and have even heated rotors to the point that they're glowing pretty bright, but have yet to experience an actual warped rotor.

Again, http://www.stoptech.com/tech_info/wp...rakedisk.shtml

 

interesting.

so whats causes the shudder while braking that disappears when they are turned?

 

The shuddering would be a deposit that is pushing the pad (and thus the piston) back. Your tire is probably rotating ~900 (guesstimate) times per mile, so at 60 mph, they're rotating 900 times per minute, or about 15 times per second, which is enough to be felt as a vibration or shudder. The deposit itself is small, but when the feedback comes back through the pedal, its really magnified. (Pushing the pedal 3 inches really pushes the piston a miniscule amount, as the pads are already resting on the rotor... the reverse is true when feedback comes through the other way)

 

So how do i fix this?

 

Don't overheat the brake pads, or if you do, give them sufficient time to cool down.

If you're doing high speed runs, don't come to a full stop right away. As long as you don't come to a stop, uneven deposits shouldn't happen. If you're hitting your limiter, then simply letting off the gas alone will do a lot of braking...