Got a track related question? I'll try to answer.

[troek]

pedal dance dosnt disable abs, and that dosnt look too bad to me. a little pad smearing but if your not gettig brake fade and your pads arnt physically falling apart, i wouldnt worry about it.

[DocWalt]

Originally Posted by troek

pedal dance dosnt disable abs, and that dosnt look too bad to me. a little pad smearing but if your not gettig brake fade and your pads arnt physically falling apart, i wouldnt worry about it.

yeah, just disables EBFD, my bad. No fade and no disintegration. I'll keep hammering them tomorrow

[CSG Mike]

Originally Posted by DocWalt

Getting too hot for XP10s? This is after 4 30 minute sessions at Shenandoah Circuit at Summit Point. I can't compress my braking zones any, I'm already bumping ABS occasionally and trail braking as much as I can. Stock tires are definitely limiting me a bit in that regard. I'm not using the pedal dance (obviously, since I have ABS). I'll have to snap a pic of the pads sometime this week after I get home. I've got another 4 sessions tomorrow. The brakes feel great, tons of bite and zero fade, but they feel a bit "gritty" and there's some bits of what appears to be pad material smeared on the surface.

Sorry for the crappy pics, I thought my phone focused on the rotor, I guess not.

How much pad material did you go through?

You might need to step up to XP12.

[DocWalt]

Originally Posted by CSG Mike

How much pad material did you go through?

You might need to step up to XP12.

I didn't think to check closely when I checked. Just verified that I didn't use more than half of the pads, pretty much. They were brand new before today.

[CSG Mike]

Originally Posted by DocWalt

I didn't think to check closely when I checked. Just verified that I didn't use more than half of the pads, pretty much. They were brand new before today.

Oh wow, if you went through like 1/3 of the pad, you are definitely cooking the pads. Lets step you up to XP12 next time, and also some brake ducts will help immensely.

Make sure you DO NOT use ABS, and it may be worth doing a cooldown lap every 3 laps or so, to help preserve your current XP10. For the cooldown lap, go at a pace just fast enough where you maintain cornering speeds, but do not gas (much) down the straights so you can go into the next corner without braking.

[DocWalt]

Originally Posted by CSG Mike

Oh wow, if you went through like 1/3 of the pad, you are definitely cooking the pads. Lets step you up to XP12 next time, and also some brake ducts will help immensely.

Make sure you DO NOT use ABS, and it may be worth doing a cooldown lap every 3 laps or so, to help preserve your current XP10. For the cooldown lap, go at a pace just fast enough where you maintain cornering speeds, but do not gas (much) down the straights so you can go into the next corner without braking.

I'm not sure I used that much, I just quick eyeballs it. I'll measure when I get home. FWIW well driven S2K's using xp12s still cool brakes here, it's a really demanding track for brakes apparently. Way harder on brakes than any track I've been to before anyway. There's another 86 here with ducts, I'll ask him about his setup.

Thanks for the tips too, hopefully everything goes smoothly today. Off to the track now

[DocWalt]

Another great day at the track.My brake pedal is a smidge softer than it used to be. Hopefully just needs bled. No evidence of pad smearing today, just normal rotor heat checking. I still think the XP10s won't be adequate with real tires.

That said, I'm really impressed by the stock tires. Set at 31psi cold and never bothered checking them hot since the car felt good and don't have excessive rollover. I definitely notice the BRZ's tendency to mild understeer though, a bit frustrating sometimes

I'll get a video up sometime in the next few days. Shenandoah is a blast

[DarkSunrise]

Originally Posted by DocWalt

Another great day at the track.My brake pedal is a smidge softer than it used to be. Hopefully just needs bled. No evidence of pad smearing today, just normal rotor heat checking. I still think the XP10s won't be adequate with real tires.

That said, I'm really impressed by the stock tires. Set at 31psi cold and never bothered checking them hot since the car felt good and don't have excessive rollover. I definitely notice the BRZ's tendency to mild understeer though, a bit frustrating sometimes

I'll get a video up sometime in the next few days. Shenandoah is a blast

Doh! I was at Shenandoah on Sunday - if I knew you were there I would have stopped by to say hello. Next time...

In terms of handling I was actually getting a fair amount of oversteer in my FR-S, especially in that first wet session. I think my rear tires are done. One of my friends (spec RX7 guy) wanted to drive and he was drifting almost completely around the lower level of carousel, essentially a dry 1/2 skidpad. Fun times lol, wish I had video going. With worn rear tires, I find it's easier to rotate the car in corners like corkscrew and trigger on power alone. If you can find a way to dial out some of the understeer, I think you'd really enjoy it at Shenandoah.

BTW in case you're interested how XP10 pads do with other tires, I was running them with worn Nitto NT05's. I trail-brake most corners too, but especially heavily into corkscrew, hook and trigger. I was getting odd vibration from the pedal entering corkscrew and hook. Not sure if one of my rotors is slightly cracked, the pavement is just lumpy there, or it was minor ABS pulsing. This is my LF rotor, the RF is probably a little worse for wear.

[DocWalt]

Bah. I saw a couple of 86's that weren't there Saturday, but I didn't get to talk to you or the other guy. I did see you on track though My wet session was really only wet in trigger, which caught me out a couple of times since I could still brake so late everywhere else. I really wish it had been solid wet, but there were a couple of run groups before mine.

I agree that I need a bit more oversteer. As I got faster at the end of the weekend I was noticing more and more understeer. Very rarely did I get any oversteer, but it definitely went more neutral in the trigger with power. In the corkscrew it just plowed with more power. It's pretty obvious in my videos too, the tire squeal goes through the roof as the track falls away and I roll on the power. Have you driven a BRZ on track to compare to your FR-S?

That rotor looks pretty decent. I'm not sure when I'll have time to swap back to stock pads, but my rotor has way less heat checking, but a bit more smearing. I wonder if I had more smearing because my braking zones were so much longer due to my tires... I was trailbraking pretty much everywhere, and did have some vibration into the loop, and the hook. Not really any noticeable vibration or pulsing anywhere else. I was bad about touching ABS into the hook over the bumps, but everywhere else it was pretty easy to manage threshold braking.

[DarkSunrise]

Originally Posted by DocWalt

Bah. I saw a couple of 86's that weren't there Saturday, but I didn't get to talk to you or the other guy. I did see you on track though My wet session was really only wet in trigger, which caught me out a couple of times since I could still brake so late everywhere else. I really wish it had been solid wet, but there were a couple of run groups before mine.

I agree that I need a bit more oversteer. As I got faster at the end of the weekend I was noticing more and more understeer. Very rarely did I get any oversteer, but it definitely went more neutral in the trigger with power. In the corkscrew it just plowed with more power. It's pretty obvious in my videos too, the tire squeal goes through the roof as the track falls away and I roll on the power. Have you driven a BRZ on track to compare to your FR-S?

That rotor looks pretty decent. I'm not sure when I'll have time to swap back to stock pads, but my rotor has way less heat checking, but a bit more smearing. I wonder if I had more smearing because my braking zones were so much longer due to my tires... I was trailbraking pretty much everywhere, and did have some vibration into the loop, and the hook. Not really any noticeable vibration or pulsing anywhere else. I was bad about touching ABS into the hook over the bumps, but everywhere else it was pretty easy to manage threshold braking.

Yeah trigger was pretty hairy in the wet. I'm used to minor understeer in my car, but that first session, I turned-in on maintenance throttle and the rear just came right around. I caught it, but wasn't expecting it at all and put on a small show for the Miata behind me. There was some talk in classroom that in addition to the rain, someone might have dropped fluid there.

When my rear tires weren't so worn, it was much harder to get power oversteer in corkscrew. I had to downshift to 2nd, toss the car in, then get on the gas gruffly. Not sure it's fast, but fun I remember trigger being easier to get rotation on exit. BTW I've only ridden shotgun in a friend's BRZ at an autocross. It was definitely a bit more planted, but not a huge difference from the passenger seat.

Also glad to hear that the pulsing may be normal. I might just replace the rotors before my last event since some of the heat check cracks are spreading/getting longer. Peace of mind sort of thing.

[Pat]

Here is my car as it sits now:
BFG R1-S tires at 35.5 psi hot
Stock suspension
DTC-60 pads
Togue Factory brake ducts
Motul RBF-600 brake fluid
Camber plates
2.6* of front camber
1.3* of rear camber
The car is pretty much stock other than that.
Yesterday I was at High Plains Raceway and noticed something funny with the tires. It was my first day on these tires. They are four years old and have been heat cycled by The Tire Rack. Before yesterday they had maybe one or two sessions on them. In the morning ambient temps were in the upper 40s. By the end of the afternoon it was around 70.
I experienced some graining with the front tires. Once the car had warmed up about three or four minutes and I started building some speed, the front tires would start to feel like they were driving on small gravel pieces. They would sound louder and rougher and I could feel it through the steering wheel.
When I brought the car in I could see a strip of clag all the way around the inner third of the tire, but the outer two thirds of the front tires looked perfect. The wear on the outer and inner shoulders looked right where they should be.
There were two turns where this behavior was especially noticeable (7 and 11). They are both very long turns. I would enter the turns with almost none of these bad feeling from the front tires, but as I would drive through each of these long turns, I could slowly feel them graining. By the end of each turn it feel fairly rough in the front end and the grip would slowly go away as I proceeded through each turn. By the end of these turns the car would be understeering.
It seems to me like these long sustained turns heated up the front tires past the point of where they should be. That said, these are pretty serious tires and I would not expect that type of driving to be a problem for them. Especially on my lowly car.
I measured temperatures on the inner shoulder, center and outer shoulder of each tire at the end of a session. I came into hot pits quickly, stopped quickly and jumped out to measure as fast as I could using my cheap China Freight IR pyrometer. Each of the four tires varied less than ten degrees across the tread. IIRC most were about five degrees in variance.
I don't have data acquisition available for review. If you need to see a video of my driving i can post one, but doubt it's necessary to figure out what's going on with the tires. I've been driving on tracks for 17 years and instructing for much of that.
FWIW, I spoke with a long-time national champion racer about this yesterday at the track and he couldn't figure it out.
What theories do you guys have for this kind of tire behavior? I'm kind of drawing a blank. My only theory is I need more camber up front, but honestly, I don't really think that's right.
TIA

[DocWalt]

hmm, maybe my rotor looks worse than I thought.


I'll have to drive on them a bit and see if they clear up (3.5 hour drive home (all highway) then drove to work this morning, so not much use). I don't have any track events planned for the rest of this year, so they'll live through winter anyway.

[CSG Mike]

Originally Posted by DarkSunrise

BTW in case you're interested how XP10 pads do with other tires, I was running them with worn Nitto NT05's. I trail-brake most corners too, but especially heavily into corkscrew, hook and trigger. I was getting odd vibration from the pedal entering corkscrew and hook. Not sure if one of my rotors is slightly cracked, the pavement is just lumpy there, or it was minor ABS pulsing. This is my LF rotor, the RF is probably a little worse for wear.

That's overheated pad. Time to step up

[CSG Mike]

Originally Posted by DocWalt

hmm, maybe my rotor looks worse than I thought.


I'll have to drive on them a bit and see if they clear up (3.5 hour drive home (all highway) then drove to work this morning, so not much use). I don't have any track events planned for the rest of this year, so they'll live through winter anyway.

How much pad is left?