Racing Brake compounds for Hard Track use

[ET1970]

I'm looking for a little help. I plan on taking my SRT-8 to Virginia internal raceway (VIR) this year. I'm getting everything ready for the event piece by piece. I have a '06 300c SRT that has been upgrade to the 426 with the Novi 1500 and tuned at Arrington Engines. I might add they have done an excellent job. The car makes plenty of power. Currently the best time at the track is 7.4 sec in the 1/8 mile at 95 MPH. With the extra power comes extra heat so I'm upgrading my current Setrab oil cooling system and the water cooling system to the Frankencooler. The biggest concern is braking. The brakes the come on the car are great for street performance and I have never had them fade under harsh street conditions. But we all know that the track is a different environment all together.

I'm a pretty aggressive driver at VIR. I currently track a race prepped '96 lt4 Corvette (sorry for mentioning an off brand here). The front straight away speeds exceed 140 MPH as I begin to brake into turn one. For braking on the corvette I use Power Slots cryo treated rotors and Hawk Blue 9012 pads. Even with added ducting for brake cooling I get these brakes hot. The temperatures climb to near the max temp of these pads. With use of temperature paints I have seen temperatures in the 1200-1300 degree range on the cooling fins of these rotors. But I have never had any brake fade.

With that said I'm concerned that my 300 will be able to exceed 160-170 MPH on the front straight, and as we all know these cars are closer to the weight of an ocean liner than a modified corvette, so stopping will be an issue. I'm planning on getting the Power Slot cyro treated rotors for this application, but the pads available are very limited. I'm also adding the steel brake line kits and high temp brake fluids. I have read a little about the EBC yellows, but they do not appear to have the high heat ability of true race compounds. I'm looking for a compound that can handle rotor temperature at least in the 1200 degree range (equal to the Hawk Blue 9012s) without fade. But I’m guessing that the heat may just exceed 1400 degree.

After the track day sessions are over I plan to replace the stock rotors and pads. So, now to the questions. Does anybody have any suggestions for the best possible pad for track day use only? What are your experiences with the pads that you have used? Do you know the temperatures that your pads/rotors are reaching? What are your maximum speeds at braking? Are you experiencing any fade with your current set up?

I would love to hear from you guys that have run Laguna, Willowsprings, Buttonwillow, and California Speedway. I've been on those tracks with the corvette and you experience the type of high temperatures that puts the brakes to work.

[SRT8U]

I have heard good things about the EBC Yellows on the track. I ran the Red's on the track twice and the even held up great no fade at all...top speeds here at Moroso were only about 130 or so, but lots of braking. I also swapped to ATE Blue Brake Fluid, which is great and I expereinced no fade or boiling of the fluid.

Here are the Yellows and the ATE Fluid.

https://www.bmcspeedshop.com/SearchR...ebc+yellow+6.1
http://www.bmcspeedshop.com/product_p/ate-sl6.htm

[done]

This is a long thread, but look for the posts by MattRobertson.

Lx Road Course Preparation!

[MattRobertson]

Well, obviously you have experience and have done your homework. You know exactly what you are up against. So much for the good news.

The bad news is something you have already mentioned. Weight. SRT rotors will hit 1250-1300 degrees on Laguna (temp paint). I put in powered spindle ducts and that brought temps down about 400 degrees, though (Your SRT ducts are not going to adapt to a spindle duct very well I am afraid, given the construction of the underbody bits).

Still, its not all about the peak temperature. Heat cycling kills rotors and it LOVES to hurt LX's. Check out these rotors (look at the bottom of Post #1), which I pulled off a couple of weeks ago. I have seven more like this one sitting in the garage, and that is just from the last half of last season to today.

Which brings me to Part 1 of my answer to your question: Rotors. Don't bother getting fancy. Use stock SRT rotors. They are going to crack. Probably after one day on a hard track like Laguna. Cryo'ing: Rotors will start to crack in two days. Been there and done that. Untreated rotors will be good for about three track days. Most I have gotten is four before they cracked fully in one spot (on the drive to Day 5... I carry spare rotors with me to the track now).

Do not try two-piece rotors. The aluminum hats reduce weight, sure. But they also reduce heat-sink mass. And crack faster and worse.

Just stick to SRT stock rotors. They are cheap at $95 each and since you *will* have to treat rotors as disposable items, you may as well conserve your cash.

You can do something I can't: Bias your pads more heavily to the rear to reduce your front temps. You still won't stop the cracking, but you can make the rotors last longer. I can't do that because I have very cheap SRT rotors in front and relatively expensive Wilwood rotors in the back. So while I had a ridiculously overbiased pad combo (Wilwood H in the front and B in the back) it worked splendidly on the track and evened out my rotor temps to about 600 front and rear (uh... in the paddock after a cooldown) ... but I'd rather just buy cheap front rotors. My rears are two years old and still more or less perfect. Now I use Proterfield R-4 in the rear which is still pretty hard core, but not as much as Wilwood B.

Speaking of pads... Good luck on the Brembos. Nobody I know of except Porterfield publishes friction graphs that show a range of performance over the full temp range. Hawk doesn't put out squat and I'd love to see something specific if you have it. One thing I would worry about - and I have seen nothing but bad news on - is whether the pads are designed for your curb weight. All of the aftermarket Brembo-workable pads I have seen are for vehicles 3500 lbs and under.

From what I can see, the best you can do on stock SRT Brembos is give yourself adequate performance. You can't get where you can with aftermarket brakes. If you can find a decent track pad for those stock Brembos that can handle a 4400 lb car, post it up here, because so far nobody has found one.

[CT-MSRT]

This is a long thread, but look for the posts by MattRobertson.

Lx Road Course Preparation!

ah, you beat me to it. MattRobertson is THE source of extended on track experience. He would be the man to chat with if you want to go beyond the already very durable EBC Yellow pads. If you got the money and really want to stop, the larger 6 piston willwood setup will get things done proper and you should only need to upgrade the fronts.

[Todd TCE]

What are the specs on the oe pad plate? Anyone have a plate number or an example? Part number with a pic?

[MattRobertson]

Something to think about on fluid. As I am sure you know all you need is dry boiling point since you will have fresh fluid in the lines, and bleed afterwards (at best, and during the day at worst, like I do). Wilwood 570 is cheap and has a much higher dry boiling point than ATE.

I would probably trust Hawk pads over Yellow Stuff unless EBC finally comes clean about pad performance. At least Hawk is widely used on track. EBC used to say they 'approached' 0.60 friction although they didn't provide any context. Now they say nothing concrete at all.

You can buy Porterfield R-4 for SRT pads and that performance curve is known. Good for a solid 0.50 plus or minus one all the way to 1200 degrees or so.

[MattRobertson]

What are the specs on the oe pad plate? Anyone have a plate number or an example? Part number with a pic?

If you can get Todd to get or recommend pads, do what he says!

Speaking of which, Todd I gotta get on the phone and order backup pads now. Talk to ya in a minute.

[Steve Levin]

As Matt says, with 33% more weight than a Corvette, coupled with a higher terminal velocity, there simply aren't brake setups that are going to survive for very long, so you want to focus on just on surviving. At something approaching full chat, my feeling is that brakes are going to last for just a few laps at best before you start losing lots of stopping power.

One other concern that comes to mind are hubs and bearings. They are being subjected to massive temps far beyond what they were designed for, and my concern is that the grease in there may actually begin to fail, which will lead to all kinds of bad things.

Steve

[carchitect]

As Matt says, with 33% more weight than a Corvette, coupled with a higher terminal velocity, there simply aren't brake setups that are going to survive for very long, so you want to focus on just on surviving. At something approaching full chat, my feeling is that brakes are going to last for just a few laps at best before you start losing lots of stopping power.

One other concern that comes to mind are hubs and bearings. They are being subjected to massive temps far beyond what they were designed for, and my concern is that the grease in there may actually begin to fail, which will lead to all kinds of bad things.

Steve

This is something I'm surprised MR hasn't run into... at least I haven't seen any posts of his talking about this being a problem.

It's a shame they are sealed or else they could be filled with a grease that is more application specific.

[MattRobertson]

This is something I'm surprised MR hasn't run into

This is something MR is surprised MR hasn't run into. We just checked the hubs when the brakes were upgraded a couple weeks ago and they are still fine. I may have gotten a set of freaks and, once the first bionic set wind up getting inevitably replaced, I'll wind up replacing hubs every coupla months. I certainly have talked to guys who have had issues, so I know the hubs aren't indestructible. And I've priced replacements.

My move to R compound rubber may seal this deal, although I've already run 4 days on them with the only ill effect being my wallet is a lot lighter after kissing goodbye tires that I could count on for 10 track days.

Talked to ToddTCE today and he is looking into the Brembo pad situation. If you Brembo guys can start braking as well as the Wilwood guys I'm gonna be pissed.

[ET1970]

Thanks for all of the info laid out here. I made a couple of phone calls and spoke with Porterfield about their R4 compound. They informed me that they have this available for the srt rear brakes but not the fronts as of yet. They recommended the Raybestos ST-43 compound which is available for the fronts and rears on the SRTs.

I questioned them on the temp range and they commented that they are capable of better than 1200 degrees. And the Cf was a round .65, but they were unable to provide any data on actual range and change on the Cf when in that range.

After looking around the web I found a site that claimed the following.

Raybestos ST43 Pads are a great track pad with extremely high temperature ratings (1400 degrees F), high friction coefficient, and excellent wear. These pads can be used on the street, but will make more noise and more dust then the R4S pads.

Another site had this information available.

Compound
Description
ST-38 Race Compound

Race Use Only
Slightly lower mu than ST-42.
Faster wear rate than ST-41 compound.
Good Performance over broad temperature range with minimal rotor wear.
Successful in a broad range of racing series.
ST-41 Race Compound

Race Use Only
The best high energy input racing material available.
Maintains high mu level at extremely high temperatures without sacrificing wear – for both pad and rotor.
Needs minimum 600F temp. to work well.
ST-42 Race Compound

Race Use Only

Lower mu than ST-41 and ST-43. Extremely stable average and in-stop output over a wide temperature range.
This compound has been very successful when used on the rear in conjunction with ST-41 on the front.
Best high-temperature wear of all Raybestos race materials.
ST-43 Race Compound

Race Use Only
Friction level and wear rate between ST-41 and ST-42. Stability better than ST-41, but not quite as good as ST-42
An excellent choce for open wheel and formula type cars.

anybody have any first hand experience with Raybestos and racing compound, or any stories floating around about pros and cons?

Any by the way Matt I plan to make these calipers out work those Wilwoods. Even if we have to send a few part to heaven in the process.

Added note they are expensive at $259 for the fronts and $229 for the rears

[ET1970]

Matt, where did you get the supplies for your took hooks. We manufactures fixed mounted units for the corvette, but i like the idea of being able to remove them when i'm not on the track?

also why did you use forced air (fans) for brake cooling and not just an open air inlet from a duct to the brakes? do you have any photos of how you routed the hose to the calipers?

[ET1970]

For all of those interested I could use your help. Grassroots motorsports is putting on its second annual ultimate track car challenge (UTCC) and I could use your help. All of those interested in participating in this event are to post their car on cardomain.com. Them the viewers can vote for their choice to compete at the event. So, if you would like to see a LX bodied car compete in the challenge then come to my website http://www.cardomain.com/ride/2568773 and vote (rate) in the UTCC. If you are not a member you can sign up in less than a minute and vote.

I competed the first year of the UTCC in my corvette. I was out run by car that had twice the horsepower as a stock ’96 corvette. The 300 was not ready for serious track time at that point. This year I would like to show the rest of the world that these LX bodied car are a force to be reckoned with.

Also, while you are at the site you can see videos of the car at the drag strip and a fun parade laps at Watkins Glen. At that point the car was on stock suspension and you can hear the tires squealing around turns even at low speeds. Going to my home page on Cardomain you can check out my corvette with videos at Willowsprings, VIR, and CMP.

Thanks for your help in getting the last of the projects done for this event and I hope you all enjoy the videos.

[MattRobertson]

The tow hooks came from http://rennline.com and the hook mounts were custom-fabbed by SVS R&D up in Sacramento. I had occasion to use the front one for the first time at Thunder Hill a couple weeks ago and it worked great even if the car didn't. The hooks are solid stainless steel and way more substantial than the alloy hooks you see out there all over the place. Here again: big fat car = extra care required and in this case, I wanted a hook that was overbuilt. At a typical 3500 lbs rated capacity I consider the alloy ones just barely able to do the job, although I am sure there are guys who would disagree with me.

The Rennline hooks are made for Porsches - mine is the 911 version - and they aren't much more expensive than the aluminum ones. I leave the front one on all the time but the rear, if you've seen it, hides behind the license plate, so on a track day I pull the plate and screw in the hook.

I used forced air to turn the dial up to 11 on airflow. The plain spindle duct is good for 250 degrees of reduction according to my measurements. Kick on the 175 cfm fan and its good for up to 400; typically 350. The surest way for me to crack my rotors faster or have my brakes go out sooner in a session is to forget to turn the fans on. They provide just enough of an extra bump to keep me on the track.

I consolidated the whole brake job with pics onto this page:
http://lelandwest.com/auto-tech/powered-brake-ducts.cfm