Goods

http://www.surrealmirage.com/subaru/brakes.html

Is this guy's hypothesis correct that "Cross-drilled rotors are good for fast heat dissipation and reduction in braking gasses, however they are prone to warpage because of their less amount of material, and lower peak temperature tolerance. They are good for racing applications where you need very fast cooling from high-speed stops, and where they don’t care about the longevity of the rotors. They are not practical if you want to get more life out of your rotor. Slotted rotors main advantage is that they help get rid of the braking gasses between the rotor and pad. They are good for mild to medium racing applications and for the performance minded street driver. The longevity will be greater then that of cross-drilled, yet may be a little less then stock. There are also high performance rotors that offer a combination of both slotting and cross-drilling."

I'm now thinking of only changing my pads.

Goods

Heres another article for those curious...

http://mods.firebirdv6.com/brakes.html

Kbueno

Go price a new stock rotor versus an aftermarket cross-drilled/slotted one and longevity goes out the window. Hehe.

quocman555

iTrader: (2)

I bought the trd slotted rotors and they warped too

///MDex

I'm guilty of this revival......

In any event, I hope not.

I too am replacing my TRD Slotted Rotors due to warpage.

My TRD pads may have contributed.

See in my initial new post, I am getting the C/D - Slotted - Cadminum rotors.

I hope history does not repeat itself.

Lvangundy

I had the power slot (stop?) cross-drilled rotors with some cheap NAPA brake pads and they warped within a month or so.

That sucked!

Vlad_Stein

Does anyone know what conditions cause rotor warpage?
And why some rotors warp while others don't?

I suspect that it has something to do with rotor temperature (fluctuation) tolerance, but I don't know for sure. Notice that when you buy a set of brake pads, they come with a bunch of characteristics (aggressive/mild, high temp/medium temp, dusty/non-dusty, etc.).

I have never heard of temperature tolerance rating on the rotors. I also never heard of specific mention of the material composition of the rotor (I am sure some are better at holding high temperatures than others).

TerryTCL

if you think about the way the slotted rotors heat up and cool down, it makes sense that they all warp.
at least especially if the rotors are undersized for the amount of braking is behind it...

for the amount of weight your GS amounts to, the rotors are way undersized...

when using slotted rotors, the areas of the slots are always at the coolest of temperatures compared to the non-slotted areas. no matter what brake pads are used. because of this, when the rotors are quickly cooled off... say when you drive through a puddle of water, in the rain, or getting a car wash after hard driving. the rotors will warp because of the differences of temperatures on the rotor.

i think instead of cross drilling where the rotors crack, and slotted..... dimpled rotors are the best to go with... IMHO
it creates areas where heat can escape... but doesn't create huge temperature differences on the metal.

JacobT

I'm confused too. I've been thru 3 sets of CD rotors and my current set seems warped too. Terry, the reason you provided makes sense but doesn't the dimpled ones will have the same problem too?

I believe the material used for the rotors are the most important part. Higher quality cast iron may reduce the chance of being warped. In my situation, when the rotors are cool, they are smooth, but after couple brakes, the rotors heat up and tap on the brake, you'll get the steering shakes. I've discussed this situation with several members here, that's the sympton of warped rotors. I thought the warpage is due to my SupraTT calipers but now I see people with stock brakes have the ssame problem. I believe the GS sensitive steering may be the answer. The sensitive steering has less torlerance for minor imperfection on rotors surface.

Will re-surface the rotor fix this problem? It may or may not. Because the re-surface job is perform in room temp. while the warpage is only happen when the rotors are heated up. Unless the cutting job can be performed under the temp. close to the hard braking condition, not all warpage can be fixed by re-surfacing.

After 3 sets of rotors for the past 2 years, I will try re-surface my RT CD rotors, carefully break in and see if I need another set or not. My last set of re-surfaced rotors lasted about 8 months

TerryTCL

jacobT...

dimpling would be a lot more beneficial over cross-drilled or slotted because of the overall amount of material still there for heat transfer... with dimpling... you're not creating cooler spots across the rotor like the slotted or creating areas of fatigue over hot/cold cycling like the drilled rotors.

actually, plating would add to the warping of the rotors.

if the inner metal and the plating do not cool off at the same time, the plating could warp or the metal under the plating could warp... all depends on the plating selection.

pretty much follows thermodynamics and material properties.

now, if you could have yourself a pure metal dimpled rotor with bigger ventilation vanes to vent the heat... that would be ideal...

TerryTCL

oh yeah,

those of you guys going with cheaper rotors...

the problem there is that the metal that's poured could contain a lot of impurities... in other words, a lot of mix materials... that might not combine well with the main metal...

when this happens, the impurites will create pits in the metal. and under high temperature, cause small cracks to form trying to expand.

BananaGS

here is my take on this:

Problem is due to:
-Cheap rotor??? maybe or ,maybe not

-Improper brake in period: "definitely", especially those that warp the rotor in lesser than a couple month.
(rotor brake in period will harden the rotor to prevent wrapping at later use) frequently reheat with moderate brake to harden the metal is very important

-Steering wheel is more sensitive due to low profile tires, yes, definitely.

-Powerfull brake pads: possible, but unlikely, just wear out your rotor more quickly, when the rotor is too thin it will wrap.

-x-drilled rotor or slotted design: maybe, depend on the drill or slot pattern

-braking habbit and driving pattern also contribute to the problem

ebruce2

iTrader: (1)

Dex, I am in the same boat as you. Just bought the whole CD/slotted package w/ TRD pads from Steve Ganz back in May. Totally warped already. I'm also in the process of getting things straightened out. Guess I'm not the only one after all.

Kbueno

-I've got about 10,000 on my set-up and have no problems...of course, my wife is the main driver and I know she's easy on the brakes. I took a mountain trip where I really buried my foot... no fade, no warpage. I guess time will tell. How aggressive is ur everyday driving if they are warping so soon?

ebruce2

iTrader: (1)

I don't brake very aggressively at all. My car is a daily commuter, that's all. I was told that the TRD pads are the real problem. Not sure how much truth there is to this, however.