MJJ_ZX6RR

OG, great thread - I have learned a lot reading it all. Thanks for doing this.

Quick question for you, or others. Does anyone manage to successfully use the stock *rear* NB2 sport big brake calipers on a track car? My stock brakes (other than braided lines and EBC yellows) are fine on track, with plenty of power and fade resistance but the rear calipers will always drag/bind, and require a strip/clean/rebuild after each track day.

Wondering whether to rebuild the calipers yet again, or to admit defeat and replace the calipers with something better.

Martin

sixshooter

iTrader: (12)

Compared to what?

And why is this in the brake thread?

OGRacing

iTrader: (1)

Plenty of people have tracked sport brakes. the only problem with them is your stuck with hawk, EBC or carbotech for pad choices. literally the lower level of performance choices. most people buy the 11.75" F kit and the 949 sport rotor+NA8 caliper bracket. that way you can get a fet of PFC's for the car. I personally recommend throwing the ebc's in the garbage. I've never seen a failure rate that high with a manufacture. i could go on about how i hate them, but i'll stop and answer your questions. If your rebuilding a caliper after every event i would replace it. replace the caliper and the guide pins. something isn't right in that system. now might be a good time to call up 949 and get yourself a NA8 caliper bracket adapter.

tazswing

I stopped using Hawk pads after a set of DTC-60s deteriorated in the center of the pad in my stock STi Brembos. Hawk took them back, gave me a new set. They are still on my shelf. The heat resistance and torque properties of the Hawk pads I really liked but I could not stomach the thought of another set falling apart on me while threshold breaking.

Thanks to this thread and some PMs from folks I am going to run the 11.75" V8R kit up front with the stock Sport set-up on the rear running PFCs on the front and still deciding on a rear pad, likely Carbos.

Thanks all.

sixshooter

iTrader: (12)

^mistake.

You get to keep your sport rotors and just change rear calipers and brackets. It sounds like your calipers are wonky and need changing anyway. Then you can match compounds f&r.

aidandj

iTrader: (5)

Is this from overheating the pads? (Disintegrating edge) Cobalts on 1.6 brakes, 2350lbs, 220hp.
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OGRacing

iTrader: (1)

The chipping on the edge? chipping could come from the pads getting wet, then freezing. it can come from overheating. it also can come from dropping the pads, most often that happens during shipping.

aidandj

iTrader: (5)

They weren't like this when I installed them. Used for 2 weeks and 2 track sessions.

sixshooter

iTrader: (12)

Were the rotors new, freshly turned, or used?

aidandj

iTrader: (5)

Used.

tazswing

Why? I can run the Carbotech XP8 pad without changing a thing: CT891. I'm already running the 1521 for the street so I would not even need to sand/clean the rotor.

ThePass

iTrader: (3)

There aren't many ways that you can better sabatoge a brake system that would otherwise rock than by running different manufacturer's pads front to rear.

Think of brake pads like tires - every single one has different characteristics; grip (friction), break-away characteristics (modulation), and how that friction changes over the heat range. You would never ever run different tires front to rear.

There is some leniency here, as it is common to stagger pad compounds front to rear in cases where you have no other mechanism available for adjusting the bias. But this should always be done within one manufacturer's product line as USUALLY (not always) each mfg. will design at least similar friction:heat curves into their range of pads within a certain category.

Ideally you would have your bias dialed in correctly with rotor diameter and piston sizes, and run exactly the same pad on all four corners.

-Ryan

OGRacing

iTrader: (1)

do not sand a rotor. Brake manufactures literally use 1-2 million dollar lathes to turn rotors with an accurate amount of run out. after that your pads and rotors can accurately ware together. you take a big step back in run-out every time you put it on a $500 napa brake lathe. thinking of rubbing sand paper on it makes my head hurt. also don't turn rotors. if the rotor's so out of round that you notice it, your going to need to remove a ton of material. that material is needed to keep thermal capacity consistent. if you get to the point of needing to tun a rotor, throw it away.

OGRacing

iTrader: (1)

i got to see these things. post pics

tazswing

I hear what you are saying. My naive sense is that staggering compounds with-in the same brand (for instance Hawk notes that DCT-70 front and 60 rear are acceptable) and between different brands (as I have proposed) is not creating much difference esp. if you are targeting similar MOT and Mu.

Yes, the general characteristics of different company's compounds will heat/cool/behave in a different manner possibly creating the issues you are referring too, but I have difficulty believing that mixing pad types within the same manufacturer (DTC- 70/60, XP10/8) is that much better than mixing brands.

After reading your repose the one thing that has stood out to me in doing some more research is that I have ABS and not mixing compounds seems to be a better way to keep the ABS from being a pain on the track. I have not purchased rear pads for the track yet so will dig some more.

ThePass

iTrader: (3)

Switch to 1.8 caliper in the rear with 949 bracket and run PFC 11 pad. You won't regret it.

Running different pads front to rear can result in a huge variety of results of course. You may get lucky and put together a combo that is at least similar enough that it doesn't create glaring or unsafe issues. You might be in for a wild ride on your first time out and realize you've wasted your money. In every personal experience of mine, running pads from different manufacturers in track/racing applications has been terrible. Most recently I had some PFC01s in the front and DTC-60 rear. One is a great pad in its own right, the other an excellent pad. Together, terrible.

Unless you have infrared sensors on your rotors and KNOW what temperature range your pads are operating at, you don't even have enough data to begin to choose two different pads to combine together. I have IR datalogging on my rotor temps, but my data will not be your data. You need to know what your setup is doing. After a good amount of experimentation with different pads I have concluded that the most consistent and best performing combo is to run the same pad all around. Add a proportioning valve to dial in bias. Add a remote adjuster to make it adjustable in-cockpit while you're on track even. You sure can't swap pads while running down the front straight.

-Ryan

OGRacing

iTrader: (1)

I hope you don’t mind me using your comment as an example. the thinking is that mixing Compounds within manufactures is ok. well that depends on the manufacture. Hawk for example, the dtc 60 will make more TQ than a DTC70 under 300*. The dtc60 has a 25% rate of change over its temperature range. so if we look at a common and simple DTC70(F)/TDC60(R) combo. it's very possible to have a rear rotor temp under 300*. so going into a turn after a long straightaway you could have a rear biased system, as you approach the apex the bias could then switch to a front bias. all of this is happening while you're checking your mirrors, finding your turn-in, looking to the apex, and your foot hasn't moved. it's the recipe for flat spotted inside front tire.

Passy is suggesting running the PFC. that is because PFC's compounds are very consistent. the pfc 11 for example has only 4% change in TQ in a temp range that starts at 200* to 1600* (compared to hawks 25% change with 200-1400* range) also at no time will PFC's compounds Mu "cross over" each other. the 14 compound will always have less tq than the 11 etc. etc. it goes the same for all top level motorsports pads. PFC, Padgid, Project Mu.

What we don’t know is Carbotchs Mu output. Putting a unknown compound in the rear could be the same as running the 70/60 compound. That’s why he was trying to save you and get you on the proven performance path.

emilio700

iTrader: (3)

For reference

OGRacing

iTrader: (1)

Using PEAK Mu, is virtually pointless. i need average, and can you get a Dyno graph?

ThePass

iTrader: (3)

Friction change related to temperature is just one factor. Different pads have different modulations characteristics. PFC has the lowest amount of latent friction that I've experienced in a pad. This makes for very, very smooth modulation.

Pair them with another pad on the other end of the car that has more "stick" when you release the pedal, and you're looking at a car that will completely change braking characteristics as you progress through the pedal's travel. There is no way to fix that other than correcting your pad choice.

-Ryan