Track Day Brakes - Operating Temperature Range
 

Advertised operating temp ranges for commonly used track(able) pads for the RX8.....

Cobalt Friction
XR-3________ 50-1600 deg. (Front)
XR-4________ 50-1500 deg. (Rear)
GT Sport_____ 50-1200 deg. (Front/Rear)

Hawk
HT-14_______ 300-1400 deg.
HT-10_______ 300-1300 deg.
Blue________ 250-1000 deg.
HP Plus______ 100-800 deg.

Porterfield
R4_________ 450+ deg.
R4S________ Ambient-900 deg.

Carbotech
XP12_______ 250-2000 deg.
XP10_______ 200-1650 deg.
XP8________ 200-1350 deg.
AX6 (Formerly Panther Plus)
___________ 150-1250 deg.


Please feel free to add any others.


__________________________________________________ ______________

Looking at these all listed helped me paint a better picture as to the spectrum of compounds which we have as options. It's definately helping me make my post HP Plus choice clearer.

Racing Brake :

ET300 not rated
ET500 up to 1000 deg.
ET700 up to 1200 deg.
ET800 up to 1400 deg.
ET800 up to 1600 deg. - 300 deg. minimum temp.

Either Cobalt Friction has some very unique and innovative compounds, or their numbers are advertising hype...50 degree cold bite on a 1600 degree pad?:uhh:

Yeah, I don't get that either. I used Cobalt Friction 3 or 4 years ago on a Honda Prelude (also 3000 lbs. car). Not sure if their compound has changed much, but back then they had NO cold bite. Once warmed up they were fantastic though. Felt they had more stopping power than the Carbotech XP10, but the Carbotechs have pretty good cold bite even when rated at 200. I can drive to the track on the XP10s without any problems.

friction coeffecient graphs look like a dyno chart, but with temp instead of RPMs. So think of it as mazda saying that the renesis produces power from 500 to 10,000 RPM. While it's technicallyt true, it doesn't tell you how much or where.

Sure, if you apply any clamping force to the rotor, with any medium, you will generate some measureable coefficient of friction...but, that isn't the description commonly used in describing "operating range", which implies the pad compound is actively transferring material to the rotor...which I can't see happening at 50 degrees on a 1600 degree pad :)

I'm going to call Cobalt Friction tomorrow to inquire more about this. I've been wondering myself.


I want to keep pad swaps to a minimum, so the Cobalt Friction GT Sport looks like my #1 option.
#2 would be running Porterfield R4S all around for daily driving and swapping in R4 pads up front for track days.

Spoke with Cobalt Friction today.
They recommend an XR2/XR5 (not listed) combo F/R for advanced HPDE run groups on our cars.
They claim their pad is interchangeable with any other pad as long as there's a proper bed-in. They also mentioned that it's perfectly fine for one to drive to/from the track with the XR series of pads due to their decent cold bite characteristics.
Also mentioned during the conversation- their pads are easy on rotors, however, they highly recommend not using them (even the GT Sport) as daily driven brake pads.

On another note,
I had spoken with Hawk yesterday and they outright say that their Blue pad is harsh on rotors, recommending the HT line of compound instead.

And yet another note,
Spoke with Porterfield and they maintain that the R4S as a rear pad will do just fine with the R4 up front.

Good information which makes sense, to me, anyhow! :)

Well, I'm determined to do as little pad swapping as possible for track days (it just makes these events much more enjoyable), so I'm going to give the Porterfield R4S a try. I'd like to see how they compare to the HP Plus. If they're overwhelmed, I'll throw in the R4 up front.

The HP Plus really dust way too much for daily use, plus the amounts of dust at track days is pretty high - I'm going to have to take a speedball to my stock wheels to get the black out- they've got some serious dust deposits that won't come off from regular washing, so hopefully the R4S will help in that department, as I'd like to preserve my new daily driver wheels.

Track day before/after pad swaps both front and rear may be inevitable. we'll see.

sorry, those numbers don't really mean sh-t, particularly on the low end

you also forgot to list the Hawk DTC compounds, those are all the "old" compounds

Hawk tech. didn't recommend DTC. Said to stick with HT series.
DTC seems to be for high horsepower, heavier cars (GT class cars and up).
The operating range on the DTC line begins at 500 degrees.

A guy next to me in the paddock one day tried using a DTC pad and I saw his new rotors crack in several places. The temperatures were really, really high. His brakes were smoking for about 10 minutes after each run.

Also, this comment really annoys me. Please explain why you believe they "don't mean sh-t."

If the car's braking is effectively done within a certain temperature range, then why get too high of an operating range of a pad? Conversely, a pad with too low of an operating range for the application and the pad loses its characteristics (fade). Thus, analysis of the pad's range does bring merit.

Comments like the bolded above makes members take your own perspective on things with a grain of salt, ultimately, not contributing to the forum's agenda of technical discussion, and ultimately, leaning more towards straightforward insult typically reserverd for the lounge. In my opinion, this tarnishes the credibility which you wish to assert yourself with.

I can vouch for the R4S on the rear. Drove 2 yrs 10k miles and 5 track sessions with an addtional two Auto X.

I still had 30% or more pad left when I replaced them this year.

Did you use R4 up front? If so, how was the bias in feel?

Hawk catalog used to claim ~1600F for the HT-10 and HT-14. They've been downgraded in the catalog now that DTC-70 and -60 are their top materials.

Three respected brands haven't been mentioned.

PFC 01 and 97 are awesome sprint race compounds. RX-8s without FI probably don't have any use for them.

Some Pagid pads are pretty much unbeatable for endurance racing, as long as temps are kept within limits. I'm interested to find out if the effective temperature management of the generously-braked, underpowered RX-8 makes the economics work out well for them. Pagid Orange is a good dual-purpose material, but can squeal pretty bad when cold.

Ferodo DS2500 is a nice, if dusty, dual-purpose pad.

I haven't bothered to see which of these pads are available for RX-8.

Also, the Axxis ULT is a really great value, and I may try it on the track with street tires (but not r-comps). I have a friend who uses it in his '99 Miata with RA1s. The failure mode when maximum operating temperature is exceeded is uneven material transfer and judder. If you stay under that limit, it's pretty nice.

Is anyone wired up with a sliding shoe thermocouple to log rotor temps around the track?

I think I did for the first 6 months but since then I have used R4s front and rear.

The good news is I bought an extra set and it was in the garage for a year.

Old posts I realize, but I'll add my ongoing user experience. I have used the Cobalt Friction GT Sport for over 1 1/2 yrs now. Car is daily drive, but mostly leisure and track use, no commuting, I have another car for drudge work. The advertising about 50 degree-1200 use range is not just hype in my experience.

I've driven in sub-zero winter, spring, fall, summer and on track - I haven't been able to notice any difference in grip cold to hot - none. They work and it's not that I have to stand on the brakes when cold...there really is the same immediate friction and braking every time, as far as I can determine.

I never removed the pads until yesterday- and I found the wear on the rotors was minimal and they are still flat and true - no groves or ridges. I have an '04 ('03 delivery) with original rear rotors and RB slotted 2p fronts 2.5 yrs old. I'm unsure why CF says don't use these pads as a DD, they seem to work fine as far as I have experienced. Tha perfect combo track/street pad IMHO.

Yes there is significant dusting, but it does seem to wash off no problem, I do keep the car clean and wash the wheels often and regularly so I don't let anything build up on my Enkei RPF1s.

Yes there is a bit of noise, but only when you are coming to a complete stop. Annoying perhaps, but what ta hey - they're performance pads after all. No biggie.

But yesterday I did take the pads off, which was a good chance to inspect them closely. There was 1/2 material left in the front; 2/3 left in the rear. That's perhaps 12K miles of use.

After a good brake cleaning I replaced those good guys with the above mentioned true track pads XR2/XR5 combo. Three days of track this upcoming weekend. I hope I'll be as impressed with these as the GT Sport!

those numbers don't mean sh-t because they're just general heat ranges, you need a mu vs temp graph to fully understand what's what. Many high heat pads will grip decent at low temp, but are very hard on the rotor surface until a certain temp is reached. Heat ranges don't tell you much because it really boils down to what the actual friction coefficient is. These are much more useful than some general temperature range quote:

https://www.rx8club.com/attachment.p...2&d=1112227726

https://www.rx8club.com/attachment.p...1&d=1217284452

a couple others to consider for street/track duty

EBC Yellow
Porterfield R4-1

Raybestos makes some decent track-only pads too.


.

:uhh: I'm not sure to whom you're venting Team or in regards to which of the posts above numbers you're dissing...you said approx the same comment in Feb above...maybe refering to that...duno.

On the other hand, as mine is the 1st post in 5 months and if you are refering to my comments, I'm afraid I don't get your need to defend some technical points about EBC pads or mu or whatever you're in a heat about.

Rather I'm giving my real-world experience. Charts and graphs are really great for cold winter at home debating jousts, so thanks for sharing that. But real world testing and observation gets someone looking for pads to the meat of the matter, I'd wager. That's why I'm relating what actually happens on our car with these pads...for for the benefit of anyone interested. :confused:

no heat, I just never came back to the thread and only just saw SouthFL's post asking me to clarify my position, not sure why you guys always have to be wearing your oversensitive granny panties

and if charts are great for cold winter bdebating contests then general temperature ranges, which this thread started on, are only good for wiping your butt after a bout of bad mexican food

..oh...bad restaurant experience...now I understand... verbal overflow :rolleyes:

Very nice technical post Team. Good information there.

Spin, thanks for the GT Sport feedback.

One thing to keep in mind - although the graph goes out to 1300f, Porterfield recommends using the R4-1 primarily when the pad temperatures are under 600f and peak temps do not exceed 1000f.

The Axxis Ultimate is a decent street and autocross pad, and may work for less aggressive drivers on street tires. That said, I generally run RA1s in an instructor group, and I found that these pads faded noticeably after five or six laps. They also (as you mentioned) left some nasty and uneven deposits on my rotors.

I wouldn't recommend these to anyone for aggressive track day use.

SouthFL, I think one of the contensious points here in this discussion is the widely held belief that (for track style pads) there (must be) is a elevated temperature where pad-to-rotor friction coeficient becomes optimal. Typically this can only be achieved under track conditions.

What I see here is discussion about a point that may no longer be valid for new style pads. That is, specifically, that now technology improvements have eliminated the temp related disadvantage in high friction race pads.

Cobalt Friction Carbon-Ceramic pads have (apparently) been able to extend the 'normal operating range' down out of race condition temperature back into everyday ambient temperature while keeping the high friction characteristics. If so, then that discussion point is a non starter really (and happily - I not just trying to simply diss anyone's favorite pads)

Although I don't have any fancy charts and graphs to quantify this, it is helpful to read the brief synopsis of their technology that they post and get a bit more detail of my conversations with them and their suppliers:

What I was told by their engineers (that goes directly to the point) is that ALL their pads are race quality, not simply modified street pads. The key point to take away is that their prime measurement is of friction level and friction characteristic, not particularly heat range. They don't use any binders, so they are not subject to melting or glazing limitations such as other pads experience. They use only high-pressure to form their pads from the raw materials.

*******
For example, in the case of the RX-8, I was told that RX-8 race teams testing their pads came back with the following emperical choices:

1. Drivers found the most usefull characteristic was high friction front pads and much lower friction rear pads so as not to upset the car under heavy braking.

2. Having all their pads to choose from, the favorites were the XR2 in front. This had the characteristic of an immediate high friction bite followed by an immediate reduction in friction, thereby allowing the front tire to 'squat down' and expand its footprint without locking up, then the friction level goes up again as continued braking is done. Maximum footprint, maiximum friction without needlessly engaging ABS.

3. Having all their pads to choose from, the favorites were the XR5 in the rear. This is a special pad not shown on their web site but one that was developed especially for rear drive cars that tend to shift weight forward under heavy braking, and potentially upsetting the car's brake balalnce and handling.

To that end, the XR5 friction characteristics start with a moderate initial bite followed by a slowly rising friction curve. This helps keeps weight transfer down, and stabilizes the car while braking.
******

I became interested in these pads just because of this kind of engineering, something unlike the other pads available and think it is something worthy of further investigation. It literally allows "tuning" brake pads to the application, to the specific car even. And I didn't want to be changing pads at the track just so I could have superior braking. So the low temp character was important for that selfish reason alone.

But back to this discussion here, perhaps the discussion is at loggerheads as some are working with one frame of reference (heat vs friction) and I am working with another (friction vs time) as the main quality determination and of of what works best.

I hope that some of this verbose explaination makes some sense to others and gives others some insight they might put to use themselves. I have these new XR5/XR2 pads now, so I can give some 1st person feedback soon.

^



What's interesting to observe is the range of the Cobalt Friction pads, which you've confirmed, offer flexibility not previously seen. This was my original intent on posting operating ranges- to find a pad with a broader range than the one which I was using, looking for a pad with somewhat higher range than the HP Plus offered (800 deg.), because I was experiencing fade with the HP Plus. The Porterfield R4S offered a 900 deg. range, and as expected, has offered more sustainability at the track, as there is definately less fade than with the HP Plus. Only bad trade-off has been its low friction bite throughout its operating range.

^ and as in your analogy, for example, Honda V-Tec technology, and those that have followed, all the way to the latest continuously variable cams, have eliminated for all intents and purposes those discussions about what is the 'best' cam.

And as the quest for perfection goes on.... we are all the winners!

^
Hehe, sorry for deleting my cam lobe profile analogy.

Cheers.

IMO the problem isn't always the pad you use. Other factors like the tires you use, amount of air pressure in the tires, air in your brake lines, suspension setup or even alignment can feel like an over worked pad.

I have been very competitive @ Time Trial Events with the Hawk HPS pads, OEM Rotors and ATE Blue fluid and have not experienced any fade with track temps varying between 90 to 130 degrees.

I regularly drive a track that is very hard on the brakes...and the HPS don't hold up to hard braking at over 120mph without a lot of cool down time. If you get that you might be OK...but 2-3 hard corners and they get real slimmy feeling

The temp range of the HPS 100-800 deg. (same as the HP Plus), but the Plus can sustain up to 900 deg.

Personally, I would think that Sebring would turn the HPS into toothpaste. The HP Plus can barely sustain lapping there from my experience with it.

I'm going sample the EBC Yellowstuff at Sebring in a couple weeks. I've always wondered what these cheap pads have to offer.

I loved the Carbotech XP-10/8 combo on my one track day.

Incidentally, I have a set of barely used three-20min-session Carbotechs for sale if someone wants to buy. :)

I have a set EBC yellowstuff pads coming for the front of my Honda Ridgeline truck. These are not the same as their yellowstuff track pads, but are instead a derivative made especially for trucks/SUVs doing towing duty. I'd be interested in hearing what you think about about the EBC yellow track pads. EBCs biggest problem seems to be distribution. They have a catalog full of pads that nobody seems to carry and take 3 weeks or more to oder in. Some of the pads they list part numbers for are not available period, like the rear pads for my truck.

I'd be interested in knowing if the yellow track pad actually has tapered leading and trailing edges as shown in their marketing pics. You would typically only do this for a basic street pad, not a performance pad. The Porterfield R4-1s are 100% full thickness across the entire surface as are most other track-oriented pads.

^
I'll be sure to chime in with an update on the yellowstuff. Thanks again for the chart you posted above. It made me consider them.

I agree with this statement. I would be running a staggered dedicated track pad compound myself if I weren't still searching for the elusive perfect streetable track pad. The Cobalt GT Sport pads seem to fit that bill, but I'm going to try the yellowstuff first. I don't mind swapping pads before events. It's the -I'm so tired I can barely swap my tires out let alone swap brake pads- scenario after the event which I'm still trying to avoid, as well as avoiding to have to work on the car during the work week to put streetable pads back on for the commute.

Very nice and smooth 2 min lap for MT, he didn't even look like he was pushing it much. I'm surprised how well a good Mustang setup does on track. Certainly the equal or better of an 8, sadly :icon_no2: There was a Canadian fellow at MT and Calabogie (maybe the same - right next to you I think) and we had great fun together and seemed to be nearly matched.

How did you find the GT Sport to X2/X5 Upgrade? Did it help your braking and entering? What was your best lap time, braking Gs w/the new pads?

I was feeling the same exhaustion as you SouthFL - I guess I'm a bit lazy too :) but I found the solution. Now I've been changing tires like a pro ... and with minimal effort to the point I think one track day I changed between my r-comp and rain tires maybe 3 times! Although I'm not down to the 7 seconds switch of an F1 team, I'm in the 7-10min range with hardly a sweat :lol2:

The solution was 2 things:

1) http://www.northerntool.com/webapp/w...2878_200342878

You'd not think twisting lugs would drain so much of your energy, but when you think about it and consider... 5 lugs x 4 wheels x 2 take off then back on = 40 lugs per change.... Whew!!

2) Use your low profile floor jack at the front side jack point - It'll take both wheels on a side easily off the ground with just a few pumps.

Changing pads at the final go-home tire swap would only add perhaps 4-5 min per wheel - one bolt off, one bolt back on at 25 ft/lbs.

If you think about it, given the function of brake pads and the physics involved in the task given, you probably will have an easier time finding Bigfoot...

You may come up with a compromise that you can live with, but it will be a compromise :)

Yes, I think it's time for an impact wrench. The low profile jack purchase was also very helpful.

The front pad swap is very easy. Rear pads are a bitch to swap out if the street pad is thicker than the track pad. Perhaps the impact wrench could be used to twist the piston back in? That would make things easier. Pushing/turning rear pistons back in by hand would be a real pain in the ass to do at the track. It's tough enough to do at home with no hurry.

The ideal would be to leave in the rear pad for track/street duty and have a dedicated track pad up front for track days so that only the front needs to be swapped out. The Porterfield R4 (front) / R4S (rear) combo is a possibility.
I can also talk to Cobalt Friction to see if the GT-Sport in back could be paired with another one of their compounds up front.
These cars really need a staggered setup to keep the rear end in place under hard braking.

Actually that's what I do, leave the rear pads in. The rears don't squeel. I used the GT Sport previously in the rear and now have the X5 in the rear, no squeeling there. Actually turning the brake cyl in the rear back in is a snap with the brake tool ($10 any parts store) and a socket wrench w/extension. It's maybe a 60 second job. Without the tool it could be a bitch I would agree, also just make sure you're turning it the correct direction (clockwise). It's very simple...really!

I use the tool, extension, etc..... it's the force needed to get the piston to go back in under each turn which is very, very difficult. It takes me about 10 minutes of all out pushing and turning to get a piston to reseat back in fully. They are very hard to turn on my car- even with the bleeder open and the m/c cap open.

With the X5 in back, what do you use up front for street driving?

That tool set looks great! MUST GET!!!! Thanks.

^
Thanks for the info.

I put my GT Sports back in front. I'm addicited to the inital bite and friction they give and would feel virtually brake-less if I had to go back to that 'ordinary' brake feel :lol: The occassional 5 --> 0 mph noise from them is nothing compared to the superior feel and grip (I use the shims and anti-squeel goo on all my front pads).

you'll get both wheels up on one side quicker by using the rear jack point

got my SUV/Truck yellowstuff pads in, they have a very small taper on each end, not like the huge taper shown on their webpage

should get them on Sunday or Monday along with a new pair of Centric rotors, just in time for the 1600 mile tow to KC

I use the XR2/5 cobalts. Less dust than Hawk blue I used before and the wear is amazingly even. I do change out to stock pads however, even given the great brake feel for street use the 2/5 brakes squeel some when cold and not heavily braked, but work surprisingly well even cold.
The proof is in the braking and I have had no fade or trouble with modulation with the cobalt brakes and the material is easy to clean and non corrosive. They are better than the Hawk blues for my driving and are real easy on the discs.

Something interesting - This is a summary sheet I got from Cobalt when requesting more detail on the XR5 compound since there was nothing on the Cobalt web site about them. It gives some verbage to all pads in the series. I think it helps to understand their "friction tuning" philosphy.

Although I've never thought the RX-8 exhibited "rapid and high levels of weight transfer" under braking (XR2/XR5 combo), if that's what works then I'm happy - I'm sure the Grand Am teams have it figured out.

http://i240.photobucket.com/albums/f...9k/cobalt2.jpg