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Old 09-08-2011, 11:00 AM   #41
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Originally Posted by richyvrlimited View Post
pedal pressure must have a direct relationship on the amount of heat generated, you're braking harder, ergo you're creating more friction and therefore more heat.

Sure you might be on the brakes a bit less time, but they're still going to get mighty mighty hot.

Conversely I could lightly brake down a minor hill for miles without getting the brakes that hot.

F1 cars don't brake for that long, but they get to stratospheric temps (not the same as an MX5 granted, but you see the point.

I'm obviously taking the examples to extremes, but you can't rule out one or the other as effecting the heat generation, they all play their part.
Actually, that's not true. I'll try to dig up the articles on it. You would think that pedal pressure plays a part in it, but there have been lots of tests done that show the time spent applying pressure generate way more heat than how hard. You will generate SOME heat either way, that's how brakes work, but you don't generate MORE heat by braking harder.

You can't really objectively look at any car, regardless of what it is, and say, "hey, they get hot but are on the brakes for a short time; therefore time spent doesn't matter." Instead you'd have to compare two drivers, one who brakes harder, over a shorter time and one who brakes less hard, over a longer time. Which is what this article shows, if I can find it. Kinda blew my mind when it was first mentioned to me, but makes sense now.

There are some really great technical articles on Stoptech's website.
Here are a couple:
http://www.stoptech.com/tech_info/wp...rakedisk.shtml
http://www.stoptech.com/tech_info/wp...lections.shtml

In that second article, take note of Point #1 near the top. My point above about brakes not having enough ability to lock up the tires is a worst-case scenario; normally functioning brakes should be able to do that, at which point your tire selection does make a difference. Unfortunately for me, I've owned/driven a number of cars that could not lock the tires in a panic stop on a wet road (my Miata included when I first bought it). The brakes have been that bad. Some of those brakes were in reasonable working order, but the pad compounds were so god-awful that I might as well have been clamping a chunk of pine wood in there instead.
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Old 09-08-2011, 11:01 AM   #42
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How did you measure caliper temp? Also, looks like DTC-30s are for designed for gravel rally and dirt circle track use? Can't find specific data about them on Hawk's website. I am, however, seeing an operating temp range of 250-2000*F for the XP12s. So if you overheated the pads, you had to have been higher than 500*. Most racing fluid tops out at ~600*F, so you could've boiled it at that point too.

Or you were braking like a ninny and overheated the pads that way. But based on your experience and such, I would not expect that
I was going to reply to this, but your reading comprehension is so poor that it's a waste of keystrokes.

"Firebrand", how does it work?
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Old 09-08-2011, 11:07 AM   #43
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I love that link. I've warped a rotor where it was visible to the naked eye, and even more visible after a few minutes on the lathe. This article is straight-up wrong.
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Old 09-08-2011, 11:28 AM   #44
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I was going to reply to this, but your reading comprehension is so poor that it's a waste of keystrokes.

"Firebrand", how does it work?
Thanks for being a dick Where exactly did I lack reading comprehension, in the part where you failed to mention how you measured caliper temp, or the part where I listed the DTC-30 uses based on what Hawk's website states?

Also, if you think improper pad transfer can't be responsible for brake shuddering you're being ignorant to hundreds of tests with data showing otherwise. It may not be SOLELY responsible, but it is definitely a culprit. But then, you do seem to base all your data off your own experiences, so...

I also am not finding anything on Google when searching "Firebrand". I'll go ahead and assume you're talking about the stick-on temp strips that change color, rather than a pyrometer in the pits or something.
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Old 09-08-2011, 11:37 AM   #45
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Thanks for being a dick Where exactly did I lack reading comprehension, in the part where you failed to mention how you measured caliper temp, or the part where I listed the DTC-30 uses based on what Hawk's website states?

Also, if you think improper pad transfer can't be responsible for brake shuddering you're being ignorant to hundreds of tests with data showing otherwise. It may not be SOLELY responsible, but it is definitely a culprit. But then, you do seem to base all your data off your own experiences, so...
  • I'm a dick, it's kind of my thing.
  • Caliper temp was sub 500*, measured with Alcon temp strips
  • Rotor temp was 1800*f measured with rotor paint
  • the DTC-30 pad material fell off, the XP12's were tapered really bad and looked "melted" by comparison
  • You can overheat a pad, with a low caliper temperature. If my caliper was the same temp as my rotor/pad, they wouldn't last too long considering they are now made of aluminum and would melt. Today my rotor temps are ~1300 on the track, front caliper temp is 290*f.

Yes, a swatch of pad material can make a pedal shudder, but I and many others have seen warped rotors with even transfer layers.

Yes, my experience shape opinion.
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Old 09-08-2011, 11:50 AM   #46
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  • the DTC-30 pad material fell off, the XP12's were tapered really bad and looked "melted" by comparison
  • You can overheat a pad, with a low caliper temperature. If my caliper was the same temp as my rotor/pad, they wouldn't last too long considering they are now made of aluminum and would melt. Today my rotor temps are ~1300 on the track, front caliper temp is 290*f.
The DTC pad material, was it bonded to the backing plate with an adhesive, or held on with rivets? Some of the older Cobalt pads used adhesive that apparently degraded over time. Had a friend that put his car into a tirewall because the material fell out...right before a braking zone.

For sure caliper temp is not a direct representative of pad temp. In the same vein, that shouldn't exclude the possibility that you may also have boiled the fluid, which would have resulted in the soft pedal you describe. Which may have been your conclusion, I don't know. It is certainly possible to overheat the **** out of everything, resulting in faded pads and soft pedal. And maybe that was the point of your response to Savington's post.

On a completely separate note, and for my own education, the warped even-transfer rotors you all have seen, are they the standard 1.6, 1.8 or some other sized rotors? I would think generally a too-small rotor (1.6 on a turbo track car) would be more likely to warp physically.
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Old 09-08-2011, 11:58 AM   #47
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The DTC pad material, was it bonded to the backing plate with an adhesive, or held on with rivets? Some of the older Cobalt pads used adhesive that apparently degraded over time. Had a friend that put his car into a tirewall because the material fell out...right before a braking zone.

For sure caliper temp is not a direct representative of pad temp. In the same vein, that shouldn't exclude the possibility that you may also have boiled the fluid, which would have resulted in the soft pedal you describe. Which may have been your conclusion, I don't know. It is certainly possible to overheat the **** out of everything, resulting in faded pads and soft pedal. And maybe that was the point of your response to Savington's post.

On a completely separate note, and for my own education, the warped even-transfer rotors you all have seen, are they the standard 1.6, 1.8 or some other sized rotors? I would think generally a too-small rotor (1.6 on a turbo track car) would be more likely to warp physically.
I'm not sure how the pad is attached, I don't remember. The DTC-30 was a dumb experiment that a local dealer pressured me into. That pad lasted 2 sessions.

I don't think i was overheating the fluid because I had the same problem with overheating the XP12's, switched to Hawk blue the same day, and had a great pedal for the rest of the day. I'm uncertain on the fluid temp, but pretty confident in my opinion. I think Carbotech is more sensitive to overheating because its a ceramic material, and when you push it over the binder deteriorates fast.

I've seen a few rotors from Hallett this year when a bunch of the American Iron guys were tearing up all kinds of big rotors, I've seen it once on my old Subaru too. We drink a lot of beer together at NASA.

The moral of the story is the TSE biggest brakes are awesome with the M-tuned rears. AWESOME.
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Old 09-08-2011, 12:10 PM   #48
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Hmm. I agree, great pedal feel the same day would suggest that you didn't boil the fluid. Interesting. As for Carbotechs, I've just never been a fan (have used XP8s and XP10s, could never get them to bed well), and I've heard lots of horror stories about them wearing/melting in funny ways.

I was wondering about the rotors more for my own future uses on the Miata. Good to know what works though.
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Old 09-08-2011, 01:42 PM   #49
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My point was that with a brake system in proper working order can be stressed harder with stickier tires absolutely. I wasn't playing best/worst case conditions or assuming a different problem with the brakes. In the OPs case, it would seem the pads clearly suck and could be brought to the point of overwhelming the pads quicker with the Star Specs as opposed to if he were running some generic all-season tire. Also note that, generally speaking, stickier tires will allow one to carry more speed which can contribute to more heat from the brakes when entering a tighter corner. Richy understood what was going on there.

I think if the OP installs the HP+ pads, SS lines and completes a proper fluid flush, he will notice much better braking. If not, the next step would be to look into why the BMC isn't creating enough pressure.
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Old 09-08-2011, 03:08 PM   #50
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Originally Posted by hustler View Post
I don't think i was overheating the fluid because I had the same problem with overheating the XP12's, switched to Hawk blue the same day, and had a great pedal for the rest of the day. I'm uncertain on the fluid temp, but pretty confident in my opinion. I think Carbotech is more sensitive to overheating because its a ceramic material, and when you push it over the binder deteriorates fast.
The Carbotechs are an odd exception to the rule. The same compressible nature that gives them their unique modulation characteristics is the same nature that will cause the pedal to sink if you nuke them. The pedal doesn't get soft, but it does sink - that's a nuance that's hard to describe on the interwebz.

When I say soft pedal, I mean the pedal has virtually no bite until you get to the very bottom. The CTs will still bite when they are white-hot, but the bite is greatly diminished.

I wish I had video of me at Laguna with XP12s in the old "baby" 11" Wilwood/Corrado kit. I did a full session with a passenger, and by lap 4 I was double-pumping with my left foot to build pressure into 2, 5, 8, 10, and 11. By lap 7 I was pumping every single corner at least twice, and I would spend the entire duration of turn 9 pumping the brake pedal with my left foot to build enough pressure to stomp them going into 10. The fluid was so badly boiled that I actually missed my pit spot in the paddock after pulling off. At this point I decided that the 11.75" kit needed to exist.
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Old 09-08-2011, 05:07 PM   #51
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You're a dumbass. GTFO.

Slotted rotors on stock brakes makes you a F&F ricer. Learn to drive without relying on the brakes so much.
Well, its certainly an exciting/terrifying challenge to get the most out of a car without relying on the brakes. I am saving up for the wilwood at the moment, so I still have some rather impressive heat issues. Speaking of which, does anyone have some good tips or pictures on how to go about ducting the fronts?

Also, OP, do yourself a favor and go buy this book and read it.

Amazon Amazon
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Old 09-08-2011, 05:19 PM   #52
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I decided that the 11.75" kit needed to exist.
That was a great day. I was so excited after you textededed me that I picked a name out of the phone book and killed them.
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Old 09-08-2011, 08:13 PM   #53
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**** dis ****, imma get some 1.6 brakes for muh car and put sum 18z on it so it ill look like da cool donk cars wit the hughe rimz an lil brakes....cuz dats da ****.
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Old 09-09-2011, 05:04 AM   #54
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The Carbotechs are an odd exception to the rule. The same compressible nature that gives them their unique modulation characteristics is the same nature that will cause the pedal to sink if you nuke them. The pedal doesn't get soft, but it does sink - that's a nuance that's hard to describe on the interwebz.

When I say soft pedal, I mean the pedal has virtually no bite until you get to the very bottom. The CTs will still bite when they are white-hot, but the bite is greatly diminished.

I wish I had video of me at Laguna with XP12s in the old "baby" 11" Wilwood/Corrado kit. I did a full session with a passenger, and by lap 4 I was double-pumping with my left foot to build pressure into 2, 5, 8, 10, and 11. By lap 7 I was pumping every single corner at least twice, and I would spend the entire duration of turn 9 pumping the brake pedal with my left foot to build enough pressure to stomp them going into 10. The fluid was so badly boiled that I actually missed my pit spot in the paddock after pulling off. At this point I decided that the 11.75" kit needed to exist.
I find it impressive that only 0.75" can make so much difference.

I'm pretty sure hustler wouldn't notice an extra 0.75"
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Old 09-09-2011, 10:33 AM   #55
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I find it impressive that only 0.75" can make so much difference.

I'm pretty sure hustler wouldn't notice an extra 0.75"
It's more than just 3/4". That .75" is a ton more iron, the aluminum hat dumps heat (keeps bearings cool), the vents are huge compared to stock (grossly superior to Corrado rotors), and more material further out means more torque. The Wilwood rotors are remarkably superior.

It depends on what you're working with, 3/4" could be a huge increase in in pleasure.
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Old 09-09-2011, 10:35 AM   #56
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I went from 9" to 10" to 11". Makes a huge difference.
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Old 09-09-2011, 11:18 AM   #57
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It's more than just 3/4". That .75" is a ton more iron, the aluminum hat dumps heat (keeps bearings cool), the vents are huge compared to stock (grossly superior to Corrado rotors), and more material further out means more torque. The Wilwood rotors are remarkably superior.

It depends on what you're working with, 3/4" could be a huge increase in in pleasure.
I was being partly facetious, but also wrongly just assuming that the disks (rotors) were identical in construction, which patently they're not as it's OEM steel discs versus Willwood 2 piece disks.
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Old 09-09-2011, 02:34 PM   #58
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What's the thickness difference of the 11" vs. 11.75" rotor?
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Old 09-09-2011, 05:16 PM   #59
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What's the thickness difference of the 11" vs. 11.75" rotor?
The same.
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Old 09-09-2011, 05:28 PM   #60
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blabla

I wish I had video of me at Laguna with XP12s in the old "baby" 11" Wilwood/Corrado kit. I did a full session with a passenger, and by lap 4 I was double-pumping with my left foot to build pressure into 2, 5, 8, 10, and 11. By lap 7 I was pumping every single corner at least twice, and I would spend the entire duration of turn 9 pumping the brake pedal with my left foot to build enough pressure to stomp them going into 10. The fluid was so badly boiled that I actually missed my pit spot in the paddock after pulling off. At this point I decided that the 11.75" kit needed to exist.
So you took a passenger out for ~4-5 laps on a faulty brakesystem?
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