To Carbotech, or not?

[Grip]

So I'm due for new track pads and I've been wanting to try Carbotechs for a while now. However, I wanted to wait until I replaced the rotors, as I've read that Carbotechs are particular about having their own transfer layer to interact with.

Up until now I've been using Hawks. HPS on the street and HP+ at the track (I only use street tires so I think HP+ is about as harsh as I need to be at $250 per rotor. Haven't gotten rotor temps either.)

Could anyone with Carbotech experience weigh in? I'm looking at a set of XP8s for Stop Tech ST-40s. Are they really THAT sensitive to the transfer layer or would they be a better choice over another set of HP+'s?

 

[SoundGuyDave]

From experience, they are actually sensitive to the composition of the transfer layer... That said, they are a lot "softer" than the Hawk offerings, and will be a lot easier on your rotors. That said, again, because they are softer, they will wear more quickly than the Hawk pads...

What you really need to do is balance the relative cost of the pads versus the rotors, and then make your decision based on that. From my experience, Hawk and Carbotech are both excellent track-day pads, and only differ slightly in terms of initial bite. Once you're ON the pedal, they react much the same. Pick your frog, and live with the warts...

 

[Philostang]

I haven't tried the XP8s, but I have used their Bobcats, XP10, and XP12 compounds.
I always tried to run them on fresh rotors (new or recently turned). You might also get away with running emery cloth over the surface to clean the rotors up.

I currently run XP12s in Stoptech ST40 calipers for track events, and it's easy enough to swap those out for the Bobcats when the car is going to see a significant intermission to the next track event (say, 3 weeks or more). You can intermingle any Carbotech compound without issue.

If I'm going to be at the track sooner than that, I frequently leave in the XP12s for the drive home. They're not the kind of race pad that won't grip when cold, so this sort of "street" duty is fine. Trust me when I say that at ambient temps they're better than just about any OEM car's breaking I've ever driven, so much so I actually have to consciously think about keeping myself from out-breaking the moron following closely behind me. Of course, the noise becomes horrible and the dust is unsightly, so they're clearly not a suitable street pad.

When I had the OEM calipers I used the XP10s with hot street tires (the current set up was run last year on Nitto NT01 and Hoosier R6 tires). I like the XP10s quite a bit for street tire applications. Used them the same as I do now by swapping to Bobcats when appropriate. They don't bite quite as aggressively as the XP12s, as you might imagine, but they also don't have the heat capacity of the 12s (and you'll notice this later in their life - performance drops off more dramatically than it does with the 12s when the pads get worn down past the half-way point). I imagine the XP8s are going to suffer similarly, as they're really intended more as an autocross pad (as I understand it).

You might want to call Mike Jr. there, he's always happy to discuss compound recommendations.

Best,
-j

 

[Grip]

First of all, huge thanks to both of you for such informative responses! (Quick, too)

... That said, they are a lot "softer" than the Hawk offerings, and will be a lot easier on your rotors. That said, again, because they are softer, they will wear more quickly than the Hawk pads...

What you really need to do is balance the relative cost of the pads versus the rotors, and then make your decision based on that. From my experience, Hawk and Carbotech are both excellent track-day pads, and only differ slightly in terms of initial bite. Once you're ON the pedal, they react much the same. Pick your frog, and live with the warts...

So, if I gather correctly, Hawks have a sharper initial bite/release and Carbotechs are more progressive on/off?

Also, when you say "softer" do you feel that in the pedal as well? Meaning, does the pedal feel softer? (i.e. more compressible pad material perhaps)

@Philostang If I may ask, where do you get replacement rotors? I'm also running the ST-40 Two-piece setup, and I'm wondering if there's a source for rotors under ~$260.

 

[SoundGuyDave]

Grip,

Believe it or not, I think the initial bite is the other way around! The Carbotech pads hit a little harder at low pedal pressures than the Hawk compounds do, but as I mentioned, once you're into the pedal, they're very similar.

By softer, I meant less abrasive... When you use the Hawk pads at low pad temps (under ~300*F or so), they are just chewing the rotors up. Not so much with the Carbotech pads, but the converse to the situation is that the Carbotech pads tend to wear heavily, where the Hawks just don't. Even at temp, I can honestly say that the Hawk compounds last longer than the Carbotechs, but at the expense of rotor wear.

If I had to describe the difference, it would be like the Carbotechs have more carbon in the pad, and the Hawks more iron. Not the whole story (I honestly don't know what the relative compositions are), but that would be my impression...

One point that Philostang brought up that I would like to expound on is what happens once you get to around 50% pad wear... The pad material on BOTH compounds acts like an insulator between the rotor heat and the brake fluid, and once past 50%, you're going to start having to bleed aggressively as you WILL overheat the fluid. At least if you drive like a knucklehead like we do... The biggest difference here between them, though, is that the Carbotech pads tend to wear even more aggressively past 50% than the Hawk pads do, AND will transmit heat a lot more. The Hawk pads work well enough past 50% that you'll be tempted to just keep running them, but you'll pay for that in boiled fluid, time in the paddock bleeding them, and short sessions from spongy pedals if you do. I imagine that there would be an advantage in really long sessions, like an enduro race, but for the typical 20 minute HPDE format, I would just keep the pads fresh, and not have to deal with bleeding them all the time.

Trust me, I'm not trying to sound like a Hawk "fanboi," because given my druthers, I would really rather have the increased initial bite. HOWEVER, the last set of XP12 pads that I ran lasted seven or eight track-days, and once I moved to the Hawks, I got fourteen out of a set. Granted, I was experimenting to see just how much I could get out of a set, and wore them down to 1/32" (NOT recommended!), but it was interesting that there was no fall-off in braking capability (excepting fluid temps) once I was past 50%.

Summary: The Carbotech pads don't last as long as the Hawk pads. The Carbotech pads fall off in performance past 50% at a much higher rate than the Hawk pads. You can run maybe three sets of pads through on a rotor before you're done with the Carbotechs, but with the Hawks, it's closer to 1:1.

In the end, while MSP's comment about rotors and pads being consumables in the brake poll is spot on, you CAN still massage your choices to make a lower net impact on your wallet. In my case, with OE GT500 rotors being available for under $100 each, I have a lower net cost per day running the Hawk pads, even though they tend to be a bit more expensive than the Carbotech pads, primarily because the pads wear more slowly, AND I can run them past 50% if I have to. PLUS I get a pretty hefty discount on the Hawk stuff, that I can't get on the Carbotechs. Before anybody asks, no, I can't pass that on...

In your case, with the higher rotor cost, the least expensive alternative very well may be the Carbotechs! You would have to do your own math to really be sure, but for rough numbers, figure one set of rotors and three sets of pads for Carbotech, versus two sets of rotors and two sets of pads for Hawk.

 

[Philostang]

Hey Grip,

I think Dave's suggestion that you need to do a kind of cost analysis of your brake consumables is spot on. His rotors are dirt cheap compared to ours (but they're heavy! Sorry, just need some sort of consolation here), so I've taken the strategy of trying to sacrifice the pads in favor of the rotors. The Carbotechs certainly do that. Last year I did 10 track days (1 in rain), and I think I went through 3 sets of pads (one was partially used). I'm still on the same rotors and they started mildly used. I think they've got a solid weekend left, maybe more. If I were to give it a guess, I'd say the exchange rate is closer to 4:1 (pads to rotors). I think both Dave and I have been pretty impressed with how much better the larger 14" rotors are dealing with the heat. I wouldn't have expected that sort of exchange rate on the OEM rotors.

As for where to get replacements, look to RacingBrake. I haven't used them yet, but Sam has recommended them (and I believe he carries them, though they're not on his site yet). You can see them here too: http://www.racingbrake.com/355x32mm_p/14041-311k-02.htm

Cost is decent relatively speaking...but ouch, this 2-piece stuff hurts no matter which way you look at it.

Best,
-j

 

[Sam Strano]

I do carry Racing Brake parts. I also tend to use Hawk pads (but carry others, Ferodo, PFC, Porterfield, Raybestos to name a few).

Hawk is a known quantity, it's not a struggle to get them, they work--and in cases of swapping pads you don't have issues between street and track material transfer on the rotors. Hawk street will work find after Hawk Race have been on the car and vice-versa.

 

[Sleeper_08]

Last year I ran Carbotech XP10/XP8 f/r on GT500 rotors and stock rears with front brake cooling. I ran 10 track days and went through 2 sets of pads. The fronts lasted well and still have about 1/2 depth. The rears should have been replaced earlier as they started chewing up rotors at the last event. Considering the price of a stock rear rotor that is no big deal.

I installed the track pads in spring on new rotors and changed them out for stock GT500 pads at the end of the season. Yes they do squeal badly on the street but swapping out pads is a PITA at the rear and more than I have energy for at the end of the day.

I am not worried about running Carbotechs on the street except as mentioned above as even though they are cold the combination of the pads and high performance street tires is more likely to result in someone piling into the back of me than vice versa.

This fall I will get a set of Bobcat Carbotech pads and then install them at the end of the season.

I am not driving my car as hard as some of those above but am slowly learning that the best way to reduce pad and rotor wear is to not use them

It is also important to make sure that you have traction control turned off.

 

[ArizonaGT]

HP+ is crap if you want to live by Andretti's credo.

Edit: or maybe not, if you want to carry the wheel back because of brake failure

 

[Grip]

So, if I gather correctly, I'll be burning out one more set of hawks, then trying Carbotechs on the next set of rings.

Now the question is...should I try a heftier set of Hawks? HP+ kinda does it, but I'm thinking I may be missing out. I think DTC-60/70s would be a bit overkill, budget and balance wise. Budget wise, I don't think $240 a set is a good idea right now.

Balance wise...I had an experience at Buttonwillow that has kept me off hot pads on the rear. I had a set of HP+'s on the back (matched up front) and by the end of the weekend, they'd worn at a 45 degree angle. As this never happens when I track street pads in the rear, it's making me think this was temp related with the floating calipers. Anybody wanna correct me? This feels like flawed thinking somewhere....

Anyway, so whatever I have up front will only be on street tires, and will be pared with street pads in back. The hardware just seems happier with this. Anyone ever tried Hawk Blues? I think they're a step up from the HP+, but actually a slight cheaper.

 

[Philostang]

I ran Hawk Blues up front in OEM GT calipers paired with...hmmm, what the heck did I run in back? I think I was also on Blues in back at the time. I liked them. OK, they were my first non-street pad, so I really loved them! This was coming off of HPS pads. There was a very significant difference. The Blues just took so much heat compared to the HPS (which are like Bobcats, very nice on the street but not at all meant for abuse), and I was on street tires then.

Moving from those to XP10s was mostly a lateral move in terms of performance (accepting the differences Dave described). The Blues make a very nice introductory track pad that will get you hooked on them. I'm not so sure about the split from Blues up front to some street compound.

Best,
-j

 

[ArizonaGT]

FWIW we get an entire season's use out of a single set of DTC60s in the front, but that is with ST-60 calipers. I know the stock GT calipers induce some pad taper.

 

[Grip]

@Philostang - Well it can't go "bad" I'd think. ("What could go wrong?!") The HP+/street f/r mix works well enough that I'm willing to give it a try. Failing that, I still have the tapered set of HP+'s for the rear.

@AZGT - it's precisely that taper phenomenon that I deal with in the rear with the HP+...I think I'm gonna try to ghetto-solve that by running some tubing down the LCA's to get some air to the calipers. Might help...couldn't hurt.

 

[Philostang]

"Give it a try" is always a viable option...yes?

My first track event was bone stock, factory pads and all. I gave it a try. I also gave myself some pretty scary moments and a direct education in both pad fade and fluid boil. The HP+ is certainly a far better pad than Ford OEM stuff, so what the heck! Give her another whirl.

Now the rest of us can lay dibs on how soon you move to Blues or better. If you get a chance to ride in another Mustang with some track pads, I give you 5 minutes to "Holy cow! I gotta get me some of this!"



Best,
-j

 

[SoundGuyDave]

What axis is the taper wear in? If you're getting taper wear front to back (front more worn than the rear), then you most likely have a stuck slide pin... Pull the pins out, clean them up with emery cloth, and lube liberally with anti-seize compund. IF, however your wear is top to bottom (tops more worn than the bottoms), then you have an altogether different issue. Replace the calipers. What happens with them (much more pronounced on the PBR-style 2-pot stock GT fronts) is that with sufficient heat, the aluminum casting itself distorts, allowing the fingers on the outside of the caliper to spread outward. That creates the vertical taper wear, and the only solution is to throw new calipers on. I've seen some "ghetto" rear brake ducts on the FR500S, where they essentially zip-tied some duct hose along the length of the LCA, then directed it to the hub of the rotor. If you haven't yet, when you have the rotors off, remove the backing plates, and stick them in a box, or in the recycle bin. Also, and I'm positive you know this, NEVER track the car with the TCS active, unless it's raining. The stability computer uses rear brake application to do it's thing, and it just KILLS the rear pads, thus generating heat...

The taper-wear issue up front is what finally pushed me into going with the GT500 Brembo calipers. I frankly got sick of swapping out calipers, even if they are available for cheap from newtakeoff.com. The fact that I no longer wreck pads with taper-wear is just the icing on the cake...

 

[ArizonaGT]

What axis is the taper wear in? If you're getting taper wear front to back (front more worn than the rear), then you most likely have a stuck slide pin... Pull the pins out, clean them up with emery cloth, and lube liberally with anti-seize compund. IF, however your wear is top to bottom (tops more worn than the bottoms), then you have an altogether different issue. Replace the calipers. What happens with them (much more pronounced on the PBR-style 2-pot stock GT fronts) is that with sufficient heat, the aluminum casting itself distorts, allowing the fingers on the outside of the caliper to spread outward. That creates the vertical taper wear, and the only solution is to throw new calipers on. I've seen some "ghetto" rear brake ducts on the FR500S, where they essentially zip-tied some duct hose along the length of the LCA, then directed it to the hub of the rotor. If you haven't yet, when you have the rotors off, remove the backing plates, and stick them in a box, or in the recycle bin. Also, and I'm positive you know this, NEVER track the car with the TCS active, unless it's raining. The stability computer uses rear brake application to do it's thing, and it just KILLS the rear pads, thus generating heat...

The taper-wear issue up front is what finally pushed me into going with the GT500 Brembo calipers. I frankly got sick of swapping out calipers, even if they are available for cheap from newtakeoff.com. The fact that I no longer wreck pads with taper-wear is just the icing on the cake...

It was front-to-rear...can't remember which was worse.

I switched to GT500 Brembos on my own car as of December 09 and never looked back! Aside from having a better pressure distribution, they also have a much wider selection of pads available in track-ready compounds.

 

[Chris B.]

I've used both the Hawk HT-10's on all 4 corners and Carbotech XP12 front and XP10 rear combination.

The HT-10's wear very quickly on higher speed tracks. The front HT-10's only lasted me two days at VIR until they were worn down to well past where they should be used any more. The previous set lasted through Monticello, 2 days at NJMP Thunderbolt, and 1 days at Pocono before that. The DTC-60's would be better for front pads than HT-10's in msot situations. I know some other Mustang owners use DTC-60's in the front and HT-10's in the rear if they want to go with a softer rear pad and not use the DTC-70's up front.

The XP12/XP10's lasted longer than the HT-10's did, but I haven't used DTC-60's on my car to be able to comapre the pad wear.

My rotor temps at Watkins Glen were 920F on the front rotors and 790F on the rear rotors. That's after pulling into the pits and they had a little time to cool down. The air temperature was 58 degrees at that time. Under braking they probably were closer to 1100F. That could be why the HT-10's didn't last long at VIR.

Another thing to consider is the DTC-60's seem to lock up easier on wet tracks than the XP-10's and XP-12's I've been told by other Mustang drivers. I haven't had the DTC-60's on a wet track yet to compare them to the XP-12's.

 

[Sam Strano]

FWIW, 10's are not the ultimate... There are HT-14, DTC60 and DTC70 beyone the HT-10's which I consider to be a intermediate type track pad. It's not super high temperature, or torque.

Remember there are 3 compounds beyond HT-10.