M104-AMG

iTrader: (8)

I purchased some cheapo RX7 front rotors ($27 each) vs. Brembos ($71 each), and with Carbotech XP9 they lasted four(4) 2-day track days (8-days total) in my 1993 Mazda RX7 twin-turbo @ Roebling Road with speeds upto 150 MPH down the front straight, before my rotors got warped and had very little cracks developing, which is about a year of track days for me.

Is there really a difference on stock-sized after-market rotors than original equipment (O.E.) ?

Are the Brembos really superior to my OPPARTS $27 rotors ?

How about rotors from www.racingbrake.com that supposedly use superior material, directional curved vanes, and heat treating (see below) ?

Are they really that much better, esp. for $124/each ?

TIA,
:-) neil

BTW: I have a seperate set of rotors for track-days vs. street
Taken from (http://www.racingbrake.com/main/stoc...eplacement.asp):
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Material
Our rotors are made of material upgraded from the OE standard of SAE J431 Class G3000 (30,000 psi in tensile strength, 187-241 in Brinell hardness). More important is our know-how and experience over decades in cast iron metallurgy. All rotors may appear the same but under a microscope there is a world of difference in metallurgical structure, which per ASTM A-247 the type (shape) of graphite shall be VII or flake graphite with “A” type uniform distribution and random orientation, and graphite size.

These are published data but achieving the optimal casting requires years’ of metallurgical experience and precise control during casting process. Carbon (graphite) contents and its structure dictate the mechanical property of the cast iron more so for a brake rotor which is subject to sudden and extreme heat load cycles during a car stopping without warping or cracking and more resistant to wear.

Heat Treatment
Severe brake duty cycles require not only good material but need proper heat-treatment to relieve the residual stress and further enhance the microstructure uniformity. Over the years, we have developed a proprietary process in temperature and time control to achieve optimal result.
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rynberg

At $27 each, were they even vented? I was tracking the car on the original OEM rotors with 75k miles on them....no cracking. Rotors don't warp either...those are pad deposits. It sounds like the pads were not properly bedded-in to me. Read the tech section at www.stoptech.com

Mahjik

iTrader: (1)

Yes there is a difference in rotors. Not all metal is the same.

Having said that, for a track FD, I would recommend Powerslot Slotted Rotors. They are more expensive, but I've seen them really take some track abuse and keep on going. Brembo blanks are also good.

Fritz Flynn

iTrader: (263)

It would seem you've already proven the point.

stick with the OP rotors.

Last weekend I cracked some fairly new looking Brembo drilled and slotted rotors through the edge at two spots. Another session and they would of cracked in 1/2. Approx 3 hours of track time with Hawke blues and 245 ff 275 rr hoosiers. Smooth brake application will also slow the wear vs an aggressive hard stab. The big difference your driving style combined with tires and pads. If you're using some very high friction pads and sticky tires you'll **** up any rotor. Drilled rotors suck no matter what size rotors you have. Avoid drilled rotors the only advantage I see to drilling is weight loss. It's possible that slotted rotors will either damage your pads or keep them clean but I still haven't figured that one out. Need further study hehe.

My driving style is wide open hot laps from start to finish I barely warm the tires before the right foot is planted. My run group allows for open passing which is a huge difference because you're never waiting on traffic etc....

Just a few easy passes into brake zones during each session will make a world of difference on how the brakes and everything else wears.

good brake ducting will also make a huge difference.

DamonB

YES.

What cracks rotors is stress as the temperature cycles from hot to OMFG hot. Slamming the brakes in hard and fast makes a HUGE nearly instantaneous temperature spike while just putting your foot on the pedal and leaning on them hard as you bring them on allows the brake parts a few extra moments to come up to temp. This makes a big difference and you'd be surprised how much you can lower brake temps and extend pad and rotor life.

Many people in fact go faster while doing this because they find their brake modulation gets better and they don't upset or overslow the car as often.

ptrhahn

iTrader: (9)

Per my reply to the same thread in the suspension section, if you've got a car with significantly more horsepower than stock, or running r-compounds, or both, the front brake rotors are just too damned small. I don't care what brand you buy, slotted or not, they'll crack quickly.

You can try DEDICATED brake ducts (not the silly R1 things), but bigger rotors DO solve the problem to a great extent. I was getting an event, maybe two out of the last set of stock front rotors I had, and with the StopTechs, I've got 16 days on them. That will NEVER happen with stock rotors.

The rears are another story, I've still got the factory original 100,000 mile rears on, no cracks :-)

ptrhahn

iTrader: (9)

I should've read your post better.

Rotors don't usually "warp" ... what you've likely got is uneven pad transfer from overheating or improper cool down. The little-bity center-of-the-face cracks are fairly normal... you'll especially see them when the rotors are cool. What you don't want are any that extyend out to the endge, or through the edge.

If you've got eight days of braking down from 150 on these, and they still aren't cracked through, you're actually not doing too bad for stockers.

ArmitageGVR4

iTrader: (13)

Not to hijack the thread, but out of curiosity, what's the best remedy for the pad deposits you guys mention? That seems to happen pretty frequently with my stock brakes. I made sure to bed my pads in properly when I got them, but after every track weekend my brakes are shaky/lumpy feeling on the street. It improves the more I drive it but it never fully goes away. Should I have the rotors turned? Should I use a better pad (currently using Porterfield R4S)?

M104-AMG

iTrader: (8)

I read the Stop Tech technical articles and found this (just an excerpt):

I also found some discoloration of the rotor and will take a picture of the micro-cracks I found.

:-) neil
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http://www.stoptech.com/tech_info/wp_padremoval.shtml

Uneven pad deposits can often be effectively removed from rotors by using a pad compound that is more abrasive at lower temperatures. StopTech has found the Hawk 9012 (Hawk Blue) compound to be particularly effective in removing uneven pad deposits from rotors. Other higher temperature performance pads may also effectively “scrub” off uneven pad deposits, however we have found the Hawk 9012 to be the best for this application.
WARNING- Only keep abrasive pads in place long enough to remove the uneven deposits. Leaving pads that are abrasive at low temperatures in service on the street longer than necessary will dramatically wear rotors.

M104-AMG

iTrader: (8)

Yes, at $27/each (www.autopartsguru.com) they are vented, and did hold up for about a year.

:-) neil