Topic: Brake rotors that don't sh*t the bed?

Howdy Lemonheads,

I'm looking for *cost effective* recommendations on brake rotors that can get past a weekend without giving you the warped wiggle jiggle every time you stomp on the no-fast pedal. The current setup is a 2004 Mini Cooper, Porterfield ST-43 pads (front and rear and they are the sh*t!), brake coolers routed to the front rotors (the cooling is ported to the inside face of the rotor), Motul RBF 600 brake fluid (also the sh*t), changed regularly. The car is mostly stock (including the brakes), I am guessing 2800 lbs ish. Direzza 3 tires, 205x50R15.

The first set of rotors used were Brembo and the fronts were giving the warped shimmy partway through the third day of racing. I replaced the those before the next days race with something from a nearby parts store (Raybestos I think) and those they were giving the warped jiggle before the end of the day. I've been running solid non-slotted, non cross drilled rotors as I haven't had much luck with those in the past (and the car has plenty of brake cooling so not convinced those will do anything other than making us delinquents look fast which would be lying).

According to the ST-43 spec sheet it is my understanding the brake pads like to run at a higher temp, could it be there is too much cooling on the inner face of the rotor from the coolers and the constant cycling of heat/cooling causing this? I will add that before I race on the pads I make sure to go out and bed the brakes to the rotors by completing progressively aggressive brake stomps from 65 mph to about 5 mph, then repeat ~8 times.

Anyways, I know there are some brake experts out there so any insight would be rewarded with a high five and an almost guarantee we will lose to you at the next race. See you rascals at Gingerman!

Re: Brake rotors that don't sh*t the bed?

The brake mavens will tell you that rotors don't warp.  What you feeling is actually pad transfer or uneven rotor wear.  My understanding is that both are caused by excessive heat, not too cool.  It's very uncommon to hear of ST-43s suffering pad transfer but I've heard of it.  It's far more common with other pad brands <cough> Carbotech.  I think what I would do is resurface the rotors I have, get some brake rotor & caliper heat paint and see what sort of temps I was getting.  I'd then call up Porterfield and tell them what's going on.  Since it sounds like you have multiple sets of rotors, I'd change them out on Saturday night until you can solve the underlying problem.  I suspect too much heat but until you can actually obtain objective data, it's a bit of a guessing game.

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Re: Brake rotors that don't sh*t the bed?

Beenthere done that, from frozen rotors to slotted to cheap... It aint the rotors, its lots of things but do NOT rule out the pads even though they seemingly out-brake and out-wear everything else.

Our recipe: Increase brake rotor size till rim limited + cheapest rotors + most aggressive carbotech pads (xp24) + lots of cooling= no shake, 1 set of rotors per one set of pads (28-30 hrs)

8 years on "A" class heavy auto car.

+ 1 for knowing rotor temps

ST43 did not work
ST47 did not work
G-loc 18 did not work
Carbotech RP2 put us through hell, that formula needs shot into the sun

Your results will vary.

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Re: Brake rotors that don't sh*t the bed?

I have almost the exact same setup as you do. Same car, same pads even the same brake fluid. My MINI doesn’t have the brake ducts though. I just took some rotors off last week that had been on the fronts for 4 races, and they had barely any shudder or wobble. The rotors are just whatever cheap raybestos blanks RockAuto sells. I highly doubt it’s your rotors, more likely something else. It shouldn’t be the pads are there are a few other Lemons MINIs running the same pad without issue.

Are you sure that you’re not warping the rotors or getting bad transfer during your pit stops? If you stand on the brakes when you stop (or worse, pull the handbrake) you can let part of the rotor cool slower than the rest and cause bad pad transfer which can chunk and cause the judder. Usually you can see by looking at the rotor if there’s chunks of pad material on the surface.

I would try blocking off your brake ducts first though, it’s possible your ST-43 pads and rotors are not getting up to temp. The MINI is a light car and not very hard on the ST-43 compound. I put thermocouples on my front calipers and was surprised how *not* hot they were getting, without any brake cooling.

Re: Brake rotors that don't sh*t the bed?

All excellent feedback, much appreciated. It was great to hear from someone else with a Mini that didn't have the problem. I can't rule out that someone stayed on the brake during a stop leading to pad transfer. Out of curiosity Gus, how many races are you getting out of the ST43's? It looks like they are about to need changing (in the fronts) and have ~4 full days on them. If you are getting much more time it seems to me that maybe it is too cool up front.

Re: Brake rotors that don't sh*t the bed?

Not a mini, but another big heavy FWD modern car. We're like 3300lbs as raced?

We were getting at least 4-5 weekends out of ST43 pads up front, and 10 races on the rears. We switched to ST45 in the front because we started getting them too hot as we got better and more aggressive as drivers. We are just using basic centric blank rotors, and they last the life of the pad without any noticeable warp/transfer issues. We use ATE Type 200 fluid. We do have ducts, I don't know how effective they are.


I don't think too cool means wearing faster. Too cool usually means less effective braking and less wear. Over heating usually means faster wear. Just a data point. The first time we overheated a set of ST-43 pads, we noticed they turned white. Raysbestos said that was a sign of overheating and that's when we made the switch to the 45.

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Re: Brake rotors that don't sh*t the bed?

I'm putting the car up on stands and checking everything over in detail tomorrow, haven't had the car looked at since Pitt. I will check to see the color of the pads. Also, I had bought a set of ST45's as the literature seems to say they are a bit better for endurance racing. Will see next race!

Re: Brake rotors that don't sh*t the bed?

...also, if you haven't seen this chart from Raybestos, it's pretty informative.

https://www.brakepartsinc.com/raybestos … ation.html

Re: Brake rotors that don't sh*t the bed?

fjehlik wrote:

Out of curiosity Gus, how many races are you getting out of the ST43's? It looks like they are about to need changing (in the fronts) and have ~4 full days on them. If you are getting much more time it seems to me that maybe it is too cool up front.

I get 6+ races from the rears and about 4 races from the fronts.

Re: Brake rotors that don't sh*t the bed?

fjehlik wrote:

...also, if you haven't seen this chart from Raybestos, it's pretty informative.

https://www.brakepartsinc.com/raybestos … ation.html


That's interesting, and does not match my real world experience at all. If I'm the first driver of the day I try to warm the brakes a bit during the opening caution laps and the first big braking zone the brakes always work terribly. After that braking zone things are fine though. But I don't have any way to actually verify brake temp, so I can't actually say that chart is wrong, just not what I would have expected.

The ST-45 recommendation came from Raybestos themselves for our car, saying they were more heat tolerant and would work with the heavy car better. Very happy with them.

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Re: Brake rotors that don't sh*t the bed?

We are running a 2007 Dodge Caliber with stock 4 wheel disc brakes.

We use ST-43 pads, RBF600 and EBC plain rotors with great success.

https://www.amazon.com/gp/product/B0084 … &psc=1

Re: Brake rotors that don't sh*t the bed?

TheEngineer wrote:

The ST-45 recommendation came from Raybestos themselves for our car, saying they were more heat tolerant and would work with the heavy car better. Very happy with them.

The ST45's are tough call over the ST43's...some cars seem to be OK with them but others (our paddock neighbors at Pitt) had trouble keeping them up to temp.  ST43's are not perfect cold but they are 70% of normal if you give them at least three laps to get up to temp.

Re: Brake rotors that don't sh*t the bed?

Go to NAPA and get their stock rotors...no fancy drilled/slotted junk.

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Re: Brake rotors that don't sh*t the bed?

OnkelUdo wrote:
TheEngineer wrote:

The ST-45 recommendation came from Raybestos themselves for our car, saying they were more heat tolerant and would work with the heavy car better. Very happy with them.

The ST45's are tough call over the ST43's...some cars seem to be OK with them but others (our paddock neighbors at Pitt) had trouble keeping them up to temp.  ST43's are not perfect cold but they are 70% of normal if you give them at least three laps to get up to temp.

Fair point. We have no problems at all keeping them at temp, but we were also overheating the 43 a lot. Loved the 43 up until we started pushing enough to overwhelm them. I'll give them credit that they never faded or gave up, but we started absolutely demolishing them in much shorter time. the 43 is the gold standard pad to start with.

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Re: Brake rotors that don't sh*t the bed?

We too have a Mini Cooper that we race. Current set up is Porsche 986 front calipers with "track" pads from Dynamic Friction I got off Rock Auto. Then we have stock rear calipers with Hawk DTC-60 pads. The fronts are not nearly as aggressive as the DTC-60's, but it feels like a really nice balance. The things stops on a dime without kicking in the ABS. We run the cheapest rotors we can find on Rock Auto as well. Got 0 brake fade at Sonoma with this setup and the pads and rotors look ready to go at least another few races.