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Old 08-24-2012, 12:58 AM   #161
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Have you considered Cobalt Friction? About the same price as Carbotech and without the precise bedding procedure.
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Old 08-24-2012, 01:25 AM   #162
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Quote:
Originally Posted by midpack View Post
Have you considered Cobalt Friction? About the same price as Carbotech and without the precise bedding procedure.
Yes, that's what I mean by CF and XR series. They are also a sintered pad like the CLs and are about $30 cheaper overall than the CL. Seriously considering them as well.

I feel like trying a sintered pad regardless just because everyone is running the carbotechs, but on the other hand, the cookie cutter approach hasn't failed me in the past.
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Old 08-24-2012, 02:30 AM   #163
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It takes me by myself with no air tools ~2-3 hours to do pads. With a buddy I can get it done in an hour or so. This won't be an issue once I'm not DDing, but I want something that lasts a while and has a simple bed in, which is why I still think a sintered pad might be best for me. Spend a bit more money so I can be lazy basically
What I used to do (before the turbo) was skip the rears and just do the fronts. Sure, the car won't brake quite as well without good pads in the back, but you're not racing, just doing track days, right? Fronts-only takes like 20 minutes, from jack up to torquing the lugnuts. Skip the shims & springs for the track pads.

--Ian
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Old 08-27-2012, 12:53 AM   #164
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I've just finished (barely) my second track day at the Edmonton Indy track this summer. There were a total of four 20 minute track sessions on Saturday and I could never finish the even-numbered ones due to boiling the brake fluid. It's a fairly high-speed track, even with the pylon chicane down the main straight to slow the street cars down to somewhat sane speeds. You can see two of my better laps below:
I've done the following to prepare for these track days (and the most recent one, in particular):
  • Upgraded my Goodwin BBK to v4 DBA rotors front and rear
  • Carbotech XP12 front pads/XP10 rears
  • TSE brake ducts, connected through the stock front air dam
  • Fresh ATE Blue brake fluid (full bleed) before first event
  • Proper bedding-in of the Carbotechs (fresh rotors; nice light-grey transfer layer after bedding)

After the fluid boiled half-way through the second session, I bled the brakes (lots of bubbles came out with the "old" fluid) and had the same thing happen during the fourth sessions. Extremely frustrating! From what I've read, plenty of people on this list can get through longer sessions, in hotter weather. Granted, my car is quite a bit heavier (2,450 lbs + driver) than most dedicated track cars, but still...

I'm open to any suggestions from the masses.
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Old 08-27-2012, 01:46 AM   #165
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Bigger rotors would help a bit. You can also step up to a higher-temp brake fluid (Castrol SRF).
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Old 08-27-2012, 01:56 AM   #166
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Bigger rotors would help a bit. You can also step up to a higher-temp brake fluid (Castrol SRF).
I considered your 11.75" kit, Sav, but the fact that my car is primarily a daily driver holds me back (my street wheels won't fit). I intend to try better brake fluid, but it seems to me that, given my set up, I should be able to drive more than 20+10 minutes (with 60-90 minutes between session pairs) without the brakes going away. Maybe I'm dreaming and it's not realistic to be able to brake from 120-125 mph to 30-40 mph, three times a lap in a relatively porky car (which is why I posted the video as a reference).

Last edited by DeerHunter; 08-27-2012 at 01:21 PM.
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Old 08-27-2012, 03:16 AM   #167
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Trackspeed backing plates with ducting, fresh (standard fluid) and carbotech pads (xp10 fr - xp8 rear * both fine for street use) resolved my problems.

For additional safety margin I have since gone to high temp fluid and 949 brake lines. Combined have made the pedal feel a lot more confidence inspiring.

P.S this was after upgrading my 1600 brakes to 1800 brakes.
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Old 08-27-2012, 04:04 AM   #168
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Quote:
Originally Posted by DeerHunter View Post
I considered your 11.5" kit, Sav, but the fact that my car is primarily a daily driver holds me back (my street wheels won't fit). I intend to try better brake fluid, but it seems to me that, given my set up, I should be able to drive more than 20+10 minutes (with 60-90 minutes between session pairs) without the brakes going away. Maybe I'm dreaming and it's not realistic to be able to brake from 120-125 mph to 30-40 mph, three times a lap in a relatively porky car (which is why I posted the video as a reference).
Some tracks are just hard on brakes, too - Laguna is like that. With our old 11" Corrado setup, I never had an issue with brake fade with the exception of Laguna, and there I couldn't even go one full session without the brakes requiring multiple left-foot pumps to maintain pressure. I will say that switching to the 11.75s solved the soft-pedal issue at Laguna, though.

If Indy is a one or two-time thing, then I wouldn't worry about it, but if you want to run there a lot, you may need the bigger rotors and better fluid. You can always pick up our upgrade kit, which would allow you to pretty easily swap between the 11" and 11.75" rotors (just unbolt the Goodwin bracket, bolt ours up, swap the rotor, and reassemble).
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Old 08-27-2012, 12:57 PM   #169
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Can someone get me up to speed with the "newer brake pads"? It's been awhile since I've raced.

10 years ago there were race pads, and there were street pads: period.

There were no "dual purpose" pads. If you tried to run street pads on the track then you would either have to drive slow, or your brakes would overheat, fade, crack/chunk out and the excessive heat would boil your fluid in no time. You would be a hazard on the track.

If you tried to run track brakes on the street, then you would never be able to get them up to temperature, the pads would brake poorly and would grind up a set of rotors in no time.

Are the new track pads really streetable?
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Old 08-27-2012, 01:30 PM   #170
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There are numerous variables to look at. Starting with even higher temp fluid is an easy place to start.

Are you running enough grip to max your corner speeds? Are you giving up too much speed at corner entry with the current setup? Your posts mention V8 levels of power with no mention of V8 levels of grip? That makes we wonder about the corner entry speeds, and grip levels, because a light miata should have corner speeds significantly HIGHER than all the heavier cars around you. If your traps speeds are higher….but your corner speeds just average with the other traffic, then work the setup details for more corner speed and the brake overheating will vanish in the process. With your lighter car you should be absolutely crushing the heavier competition in the corners.

Driving style also a variable. At Laguna Seca we had a father and son driving the very same V8 Miata (that’s an extra heavy 2600 pound Miata because of all the V8 gear). The Dad was overheating the setup but the Son in the same Miata was not having the slightest problem…and the Son was turning lap times almost 3 seconds faster than his Dad. Result was that Dad was frustrated. We put data in the car and found that Dad had significantly slower corner entry and exit speeds than his Son. Dad was actually braking both harder AND later, so late that he was killing his corner entry speeds, and he was punishing the brakes in the process. Thus, the Son’s data in the same Miata showed that the problem was not the brakes in that 2600 pound example.

I watched your video and your style look nicely smooth, you don’t appear to be braking too late that I can see, though I can’t tell from watching it if you are giving up more speed than necessary for those corners? If you are just joining the conga line in the corners with heavier cars then that’s slow for a light Miata. I notice you didn’t mention what you are running for tires/wheels but that’s part of the corner speed question (as is other areas of setup including suspension and aero). You might run slightly more tire and grip (wider and/or softer tire) for that track which may bring down the trap speeds but allow faster corner speeds. Look at easy aero mods to increase corner speeds too (which again may give up a little trap speed but if total lap time comes down…then you win on all accounts and punish the entire car much less).

I would take a look at how your brake ducts are arranged, more than half the installs we have seen have the hoses half pinched so the setup is doing more harm than good.... because compromised flow into the hoses leaves just the metal plates blocking air flow around the rotors. Too many times we take off the plates when hose flow is not ideal (hoses pinched, torn, etc) and just zip tie the hoses to the sway bar pointing in the direction of the rotors from several inches away and brake temps suddenly FALL. Assuming not pinching the hoses, take a look at BIGGER scoop and/or bigger hoses).

You can also look at mods to suck more air from the wheel/brake area. For example, look at pics of V8 Australian SuperCar front fenders….these are heavy V8 cars with relatively small tires and notice that they shield the tire from getting air on the leading edge….but include open area down low behind the tire to suck the brake ducted air out (and they reduce front end lift at the same time). We have done a little of this after the pic was taken below of NCLIGHT and it helps.
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Old 08-27-2012, 02:09 PM   #171
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Thanks for the thoughtful reply, Brian.

I'm running fresh 225/45-R15 NT-01s on 15x9 6ULs. Suspension is AFCO with 450/300 lb-in springs, larger front anti-roll bar and stock rear. Overall, I think I'm in the hunt in terms of overall grip.

I wasn't running a datalogger for these sessions, but a couple of years ago I borrowed one for a different track. With the same suspension but with 205/50R-15 RA-1s on 15x6.5 Heliums, I was averaging well over 1 g in the corners, with peaks of 1.25 or so. Peak braking g's were 1.2-1.3 (your BBK with PF-01 pads in front/stock rear pads).

From my "seat-of-the-pants" datalogger, I was pretty close to maxing out cornering grip (which has to be higher with the new wheel/tire combo). Any faster and the fronts would start to scrub. Possibly I left something on the table at the hairpins, but I think only a datalogger could prove it one way or another. I plan on getting one for next season and perhaps I can learn a thing or three from it.

The brake duct hose is unkinked and routed similarly to the attached picture (I have since, based on a recommendation from Savington, zip-tied them to the steering linkage instead of the anti-roll bar). Any suggestions for a bigger scoop (something that looks unassuming and will not compromise street driving)?

Given the dual purpose nature of my car (weighted more towards street use), I'm not likely to start adding splitters, large wings or the like. Are there any other easy (and reversible) aero mods that I should consider?

Thanks again to all who've chimed in. The brakes are the last piece of the puzzle in my quest for a decent dual-purpose Miata.
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Old 08-27-2012, 02:13 PM   #172
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If you have a prop valve (which I assume you do), where's it set? (How many turns away from max rear are you?)
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Old 08-27-2012, 02:33 PM   #173
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What about something like titanium pad shims? Supposedly that reduces heat transfer to the pistons/fluid a little.
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Old 08-27-2012, 02:41 PM   #174
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If you have a prop valve (which I assume you do), where's it set? (How many turns away from max rear are you?)
No prop valve. I have ABS and the stock proportioning is quite heavily weighted towards the rear (discovered years ago when the ABS quit working briefly). Given this, is one worth considering?

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What about something like titanium pad shims? Supposedly that reduces heat transfer to the pistons/fluid a little.
Never heard of them. Where does one source such a thing and has anyone else successfully used them?
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Old 08-27-2012, 02:53 PM   #175
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And you're boiling fronts or rears?
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Old 08-27-2012, 03:11 PM   #176
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Never heard of them. Where does one source such a thing and has anyone else successfully used them?
Girodisc makes some for other applications.
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Old 08-27-2012, 03:21 PM   #177
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And you're boiling fronts or rears?
When I bled the brakes after the second session, I had bubbles from all four corners (IIRC), but much more so in the front. I know the rotor paint for the fronts indicated maximum temps reached at least 630C (1,166F) and the rears reached at least 550C (1,022F). Perhaps the grippier pads I installed last week (XP10 vs. stock OEM) are allowing the rears to work harder and become a problem as well.
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Old 08-27-2012, 03:31 PM   #178
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OK. The bias thing might be an issue, but if you're boiling fronts too then it's probably not the core issue. When was the last time you did a full flush?
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Old 08-27-2012, 03:38 PM   #179
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Full flush was 3 weeks ago, before the first track day. Strangely enough, that day was significantly warmer (my best lap was about 1:48, compared to 1:58 on Saturday) and I had no issues with boiled fluid. This was with Goodwin v3 rotors, PF-01 pads in front and OEMs in rear.
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Old 08-27-2012, 04:39 PM   #180
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Try switching to XP12s.
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