Yeah the last mechanic shop I was in (just a regular "works on minivans" type place, but they're pretty good in my experience so far), when I was talking about rotors with them, the mechanic there seemed to be of the impression that the mfg failure rate on normal brake rotors was pretty high. Said he "often" has to lathe brand-new rotors just to get a customer's car to stop vibrating, and thus he didn't think it would be that astronomically unlikely for me to get 3 bad ones in a row (at least one from each pair, anyways), if I was just putting em on straight out of the box.

I didn't dial-gauge the first set of RA's, and I did it wrong (wrong specs in hand, see earlier) when I put on the first set of Z1's, so I can't even say for sure if they were out of spec when installed, or just were of insufficient metallurgical properties to take the abuse. The second set of RA's were definitely bad out of the box. Very first test/bed drive they were shaking. This most recent set of Z1's, though, definitely dial-gauged under 1/1000th runout at the outer edge torqued down, and then drove flawlessly.

I really don't mind that I did the other maintenance along the way. Those tie rod ends, bearings, ball joints all had some significant wear on them anyways at 32K miles (and by my last estimate, a little over 1K of actual track miles so far).

I may just have to do a complete BBK at some point in the future. For now I guess I'll chew through cheap rotors at whatever rate they die for a little bit longer.

Got back on the track this past weekend, w/ The Driver's Edge at MSR-Houston. 8 sessions over two days, CW direction (which I haven't done in a long time, but it's the direction I went my first few times at this track ages ago).

I didn't capture any data/video this time, partly because as time goes on I'm just getting lazier about caring about that, and partly because I'm starting to lose interest in lap times as a metric as I get better at feeling the car and just knowing how much I'm improving (or not) based on the feel of the car and how my car control skills are developing.... but mostly because my Android phone w/ Cyanogen is a buggy POS and I couldn't get my datalogging app to sync w/ up reliably with my GPS and OBD-II units :shakes head:.

It was a really good weekend overall.

Temps:

Really hot conditions, and I'm pushing the car even harder than I have in the past. The 19-row oil cooler really started showing its limitations, as I was hitting 260F at the end of almost every session (250 on a couple of cooler sessions with some clouds rolling in). Coolant would also crawl up 2-3 dots from its normal position, and I was getting a bit of coolant overflow (could see the evaporated splash marks around the front area of the engine). I've got time to deal with that before next spring; my next weekend is in November and ambient temps will have dropped back down nicely by then.

Brakes:

The new rotors held up ok through the weekend (as in, I didn't have to panic and/or cancel any runs), but I can already see a perfect pattern of uneven spots in the transfer layer down the centerline of the pad width in the front, and I could feel the first real hints of vibration creeping in by the end of the weekend. I'm not sure if that pattern develops naturally as a self-reinforcing regular phenomena once a few slight high-spots develop (like the suspension ripples that develop in a dirt driveway), or if it's when I hit ABS those pulses set up the start of the pattern (which is pretty rare now, I only popped into it briefly about 3 times all weekend, and quickly modulated to get rid of it).

I'm sure I'm dumping a bit more heat into my front brakes than I should be if I were a better driver. I still often start my braking zone a bit early (usually out of fear because I'm carrying more speed than I'm used to or whatever), and then realize the error as the car slows and just kinda drag it out a bit. I should at least just finish early when I start early and then get back on throttle early, or something.

Regardless, I need to make another change in pads and/or rotors to get past this problem. Even with front ducts, they're just not holding up to the abuse, and I can't keep tossing out rotors after a weekend or two. I think my next experiment will probably be just to switch pads, since I've never moved off of Carbotech during all these rotor-destruction events. I informally polled all the 350/370 guys I found at the track and got a list of pads that are working for others to pick from: Hawk DTC-60, PFC (not sure which, and they may not support my caliper shape yet?), Ferodo DS2500, Hawk Blue (with the caveat that they wear down rotors really fast, but hell they can't wear them down faster than I'm hot-spot destroying them now), and Stoptech (the guy is using their high-end street compound and said it lasted fine in HPDE). Any other input or recommendations welcome. If I can't clean up these front rotors by trying to remove deposits, I may try yet another rotor brand for fun too, maybe DBA 1-piece, or see if Wilwood makes a good 1-piece for this car. Rears are always fine, I'll probably just leave the existing rotors + XP8 there until something wears out.

Other car setup junk:

The need for some newer and stiffer coilovers is becoming more and more obvious every time I go out. Car's just too soft, and the total travel height from the braking dive back up to on-throttle is just really tall. I guess the upside is it's helping teach me to ease off the brake pedal at the right rate to counteract most of the heavy rebound, but it's still annoying and I'd probably be doing even better at brake->throttle transitions if I had more stiffness and shorter total travel. It's not so much an issue on side-to-side rolls because my heavy swaybars hold the car pretty stiffly in that direction, although in some transitions I do find myself wishing the car would finish the side-to-side weight shift process a little faster.

Also, with my skills improving this weekend I got into fuel starve a lot quicker than I expected. Only 2 dots were blacked out on the gauge (well, it switched to 3 dots blacked just *after* the event), and it was on a corner I had never had a fuel starve problem on before because I was never very good at it before :). It didn't hit until halfway down the straight after a series of rights that pushes a lot of straight-sideways G-force out to the left, and it was just a brief cut and it came right back as I eased off the throttle pedal. I should have Phunk's new system in place before November though.

Me:

Things are going well, I think. The more I learn, the more I realize I still have a ton to learn. Instructor feedback is positive, they say I'm about where they expect me to be for the track days I've been to, and that I'm approaching a new plateau of skill that I'll probably bump onto in a very obvious way in the next weekend or two, which is probably when they'll shift me up another rungroup. Right now they've got me in the Blue group (which is their 2nd-level and the one people seem to pile up in for the longest time, it's always a big field) running alternating solo/instructor sessions there (you start out all-instructor in Blue, so the half-solo part is sort of a halfway-point to the next level).

I'm getting much better at car control in corners, and letting the rear drift properly while unwinding the steering in sync and being able to accelerate a lot harder and earlier than before without feeling a ton of oversteer risk like I did in the past. Similar stuff going on in long constant-radius corners: learning to just let that back end slip the whole time and manage it with the steering/throttle input and rock around there at much higher speeds than I was doing before when I was trying to keep it from slipping :). I still really need to work on my brake->throttle transitions, reducing or eliminating the delay in the middle that lets the suspension unload a bit, while keeping that initial throttle application very fine and light. I may start playing with left-foot-brake stuff on the street a bit in the next month or two and see if I can get used to that (and if that goes well, may try a little trail braking with that foot as well).

Last session of the weekend I had some fun with a 350z guy I see at the track a lot (apparently he lurks here, hi Tim!), we got into a good groove out of the rest of traffic and swapped back and forth a bit chasing each other down. I let the fun get the better of me and had a multiple near-spin events going a bit too hot and deep into a corners and/or getting a little too gas-happy on the way out. I'm sure the instructor was rolling his eyes at me for regressing, but eh, it was a ton of fun and it let me exercise some car control and recovery / off-line skills, so it was all good. No actual spins or off-track excursions all weekend, so that's always awesome.

Oh, also I met our fellow forum member, I think TX_370Z? (oops, I got names mixed up earlier, I may still be wrong on matching up people to forum names here) out there at the track this weekend. They stuck him in Green because it was his first time out with Driver's Edge, although I think he already has a bit of track experience. I watched a couple of his sessions from the stands and he was looking really good out there, they really need to move up into Blue for the next time out, and I'm sure they will. Met another guy with a supercharged all-black 370Z out there as well, from Dallas, not sure if he's on this forum. Starting to see a lot more 370 action at these events lately, it used to be rarer. There's also an instructor running a Silver Nismo here, and one other Silver 370Z in one of the higher run-groups, that I've talked to a few times at the track but didn't run into this weekend. PM me your forums names if you're around here so I can keep track of all this heh :)

Just say no to DS2500, they have the problem you have now times 10.

The DTC-60's or 70's are pretty good, but the top picks are also the most expensive (but will last a lot longer), Performance Friction or CL Brakes are really the only way to go. Still haven't found a rear compound that I'm really happy with though. The one that worked the best for me in the rear was the pad that came with the calipers, Mintex Extreme, however I don't seem to be able to get that anymore.

Mintex rear might be good for the rear. So far as for the front there good for dd but I'd never track with them. Ever!

The ones Stillen is packing with the kit now are not the same as what they did 3 years ago, not sure why. Seem to be a different compound. I drove with the original Mintex on track and they were solid and predictable (no fade), just not quite high enough torque. The stuff they have now under the Brake Pro label is street only IMO.

Yeah I might give the CL RC6 a try up-front. Noise issues and whatnot aside, do you think they'll run ok for some light street duty between events, or do things get screwy after too many cold miles? I guess I could go back to swapping in a street pad if necc, but then I need to deal with scrubbing off the street pad's xfer when I switch back as well. I never commute, we're just talking the occasional run to a friend's house or a parts shop :)

That's the beauty of the CL's, if swapping pads you just drop them in a couple of days before and street drive them a bit. At low temperatures they will scrub off the old transfer layer and be fresh for the track. They don't need their own transfer layer ahead of time and don't need to be bedded (just seated). I've used nothing but these pads for the last 18 months and have had zero issues. Swapping back is the same deal, just leave them in for a couple of days and they will clean themselves up.

I think with low street miles you could leave them in there, they're actually not that noisy. You can go with either RC6 or RC6e (if available), the latter is the endurance compound, which lasts longer but is possibly more aggressive on the rotors (speculative).

CL Front Pads arrive sometime tomorrow. Gonna see if they can clean up these rotors or if I need to chuck rotors again :). Then I need to see how RC6 + XP8 works for front/rear balance, but I bet it's pretty ok. I was tempted to order some rear RC5+ with them, but I'm a little scared they'd be too aggressive in the rear for this car and get me back into heavy ice-mode issues.

Hey Brandon! It's Tim. Good to see you again at the track. Are you signed up for November? I'll be there.

Here's some footage I got from our last session. Pretty interesting to watch our screw ups!

Yeah I'll be there in November for sure.

I had to go back and watch again once I realized I could use your right mirror to see when I was close after that first pass. After you went back in the lead the second time I seem to vanish though. Let me dig through my list of excuses...

It's funny that in two places we made pretty much the same mistake but on different laps (going too deep in the U-turn after the front straight, and kicking the tail out on the sweeper to the back straight). I was kinda slipping all over the place that run, but it was a fun end to a long weekend :)

I don't think I've ever heard my own car going all out before, from an outside perspective. 5:10 into the vid, love that sound. Fast Intentions exhaust is awesome :)

Haha yeah I noticed the same thing! Funny how having some friendly competition with people ya know brings out some bad driving practices! I know was scaring my instructor a bit, throwing almost everything he taught me over the weekend out the window for a lap or two there!

As for after the second pass, I'm sure you had a ton of feedback to digest from your instructor and then traffic!

We need to line up more often... I'm not sure why we didn't earlier in the weekend. Our cars are pretty evenly matched.. or drivers! At least until one of us gets a 1up mod on each other haha.

Yeah I haven't heard my exhaust from the outside, and I get a lot of compliments this time around with this new exhaust than the previous single. :p

Hopefully you'll have your gadgets working right at the next event and you can record my cars funky sounds.

I actually think the co-efficient of friction is higher on the XP8's than it is on the RC5+. I believe XP8 is around 0.58-0.60 and the RC5+ is about 0.4. Problem is I think the RC6 is about 0.5, so with 0.6 is the rear it could be trouble. The ABS likes the low friction a lot better but the rear has to be the same or lower than the front.

Oh I didn't realize the XP8 was so high. The XP10/12/16 must be insane then; even the 10 felt pretty high to me in the front. Have you tried RC5+ in the rear as an option?

They don't make RC5+ in the AP Racing size unfortunately. Up front I have used RC6, 6E and 8.