wstar's Journal

SPOHN

Great vid and nice track. There was several turns that looks as you could carry more speed and still play it safe. But I know all to well how that is. When I go back to Road Atlanta there are two turns I plan to carry at least 8mph faster. Doesn't sound like much put it's defiantly putting it on the edge. Funny how that is.

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wstar

Yeah, that vid was from halfway through the weekend, I picked up a lot more speed later. The long round corner ("The Carousel") exit is obvious and easy. The other was the whole Launch + Gut Check area (the hill and following slow bendy area, where I passed that silver car with the wing in the vid), where obviously in the laps on this video I was holding back a ton. I eventually figured out better lines and speeds through there .

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wstar

No problem on the bump, this journal is long overdue for updates anyways.

And yes, I realized I made an error there some time ago, but my brake saga has been a long and varied one, and I wanted to get to the bottom of everything before I updated again. You're right about the tolerances. The actual specs are:

Thickness Variation: .0006" (all 4 corners)
Front Runout: .0014"
Rear Runout: .0022"

So yes, even after indexing, two of my rotors were out of spec in that case by my own measurement (one of the rears and one of the fronts). However, I can't say *definitively* whether the rotors were truly bad, because I did my runout measurements with the lugnuts just barely tightened on the rotors (no wheel of course). I could have made more effort to torque them down properly with a washer under the lugnut, but I didn't because even with the light torquing the readings were "in spec", except I was looking at the wrong specs I had written down , and I didn't discover my numerical problem until a couple months later when I was re-reading the specs in the service manual to measure another set of rotors.

Follow-up post incoming with the whole Brakes Rotors Saga this car has been through in recent months.

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Journal thread / Car setup details

wstar

Brake Issues Summary

I'm going to try to keep this as summarized and brief as possible, although it'll still be very TL;DR for most...

Up through Sept 2011: My brakes were fine. I still had my original OEM rotors on the car, and Hawk's HPS street pads, and no real braking issues. I had been to a few light track events / Auto-X with this setup. No vibration, just the to-be-expected weak bite and brake fade.

Sept 2011: I decided to give 2-piece rotors a shot for the rotational weight savings, while also upgrading to Carbotech's XP-8 pads for a little more track-worthiness. The rotors were from Relentless. I chose them because they were one of the only claiming a 2pc for the rear with a real weight drop back there. I had actually ordered these and PAID IN FULL for them on May 25, 2011. They didn't arrive until Sept 9, a full 3.5 months later after a very long email thread with me bugging the vendor about ship dates and getting a constant stream of broken promises all that time. And when they did arrive, some of the minor hardware bits (rear caliper pins) were missing, so I had to wait another week for him to ship those.

Also, when they arrived, the fronts were the expected 10 lbs lighter per corner, but the rear rotors (which also involve adding a custom spacer between the two halves of the rear caliper to make the caliper accomodate a thicker rotor, so it's not a simple swap...) were actually *heavier* than my 1-piece OEM rears. He did a lot of backpedalling on that and claimed I was the only one to measure that, and I must have freak OEM rears or something. Whatever. He wasn't in a mood to take back half the kit, and claimed I could use the cooling upgrade in the rear anyways (the rotor did look considerably beefier with much better cooling vane setup). So I went ahead and installed the damn thing.

Late 2011: The new setup bedded in ok. It got through one full track weekend sometime in Late 2011 without any obvious vibrational problems. I did get ice-mode for the first time on this setup. In retrospect: XP8+XP8 (matched pads F/R), plus much cooler-running stock rear rotors, plus all the heat that happens up front on the track -> more likely to hit ice mode, because the fronts fade a lot faster than the rears do, leading to rear lockup before front.

Jan/Feb 2012: Had another track even that went smoothly. After that, started noticing a slight steering wheel shake while braking at high speed on the street. Could be any of a number of things, although rotors are the most likely candidate. Tried to do some rotor cleanup before an upcoming track event: sand off pad deposits, sand down the pads nice and flat, and re-bed the pads to the rotors. It seemed to clear things up somewhat at street speeds. Got to the next track weekend and from the very first session (this was TWS, it has some *very* high speed brake zones) the shimmy in the steering wheel under braking was coming back with a vengeance. I ended the first session short because I was worried I had a real problem on my hands.

Spent that whole day trying to debug mid-event. There was a race mechanic shop on duty with a mobile garage setup for the event, had them go over the car as well. They said the suspension and bearings were fine, and it had to be the damn front rotors (which seemed insane, since these are supposedly very high quality rotors, and this only their third track weekend and they've been on the car barely like 4-5 months). Keep in mind also that before these rotors ever went on, I was already aware of all the stupid things people do to make rotors go bad, which is why my stock ones lasted 2.5 years and were still going strong. I never stand on the brakes at a stop, I never ride brakes, I always cool them down spinning before parking the car, etc. Anyways, as a last ditch hail-mary effort to save the track weekend, I let a local auto parts store try to turn the RA front rotors on a lathe to get me running again. It went poorly, the rotors got worse. Most likely their lathe and/or lathe operator just couldn't cope with doing a proper job on slotted rotors, but who knows. Called off the weekend and went home.

March/April 2011: I did some measurements to confirm the front rotors, as mounted on the car at the time, were definitely out of spec on runout. Also confirmed that the aluminum hat was showing zero runout down to 1/1000th (the precision of my dial gauge). Hard to say it's evidence of anything since they'd already been through that horrible lathe job as well. Called up RA on Mar 10th, complained a lot about the rotors' short lifespan. Blame the customer, blah blah, offered me a set of replacement front rings at retail w/ him covering the shipping. So I said ok. I had a track event coming up for April 21-22 weekend, so he had about 40 days to get me some replacement front rings. He failed to even get close to being ready to ship them on time (although at least he let me know so that I could come up with an alternative in time for the weekend).

So I ordered a set of cheap (but supposedly high quality) 1-piece rotors from Z1, the slotted upgrades they sell for $198 a pair, front and rear. Slapped em on, and made it through that April track weekend fine. I also had the Stillen front brake ducting installed for this weekend for additional front cooling (I had homebrew ducting before, but it was just to the wheel well not the back of the rotor), and upgraded the front pads to XP10 for more front fade resist. By having a better pad up front + better ducting, and not having excessive rotor cooling in the rear, my ice-mode problems seemed to have gone away.

Mid-May 2012 - At this point I was completely ready to abandon my RA kit and didn't even want the damn replacement front rings. Weight savings in the front aren't worth the reliability issues, and the rear kit is a total joke (caliper mods; heavier rotors; more weight to the outside w/ the aluminum hats; too much rear cooling contributing to ice-mode). I didn't even want to talk to this guy anymore. But he still had my CC info, and when the front rings were finally ready he went ahead and billed me and shipped them, since they were ordered just for me. I hadn't really cancelled my order either, I had just given up on him and stopped calling him, so I guess it's a grey area. Whatever. I shelved them and figured maybe I'd try them again at a later date when the Z1's wore down or something.

Early June 2012 - I was sure at this point the RA rotors were to blame, since swapping in those cheap Z1's seemed to clear up the problem. But then.... I started getting the same issue on the Z1s! Vibration under high-speed street braking, getting progressively worse. I again tried some simple pad deposit remedies right off, and it did help for a little while, but the problem came right back pretty shortly. Cancelled a track event or two while the rest of this unfolded...

June, July, August 2012 - Given same problem with two different vendors' rotors, I figured I must have some other underlying issue, even though two different shops claimed my suspension/bearings were ok from pulling on things. I figure not all suspension/bearing problems are obvious in that way, they might only appear under certain torque or loading while running the car.

So, one by one (swap a part, do basic brake maintenance, test the car with some brake bedding, find out the problem is still there, order more parts, wait a week or two to arrive and have time to install, again...), I replaced: the front wheel bearings, the front outer tie rod ends, and then finally the whole front lower control arms (it has the lower ball joint, and on this car you replace the whole arm to replace a bad ball joint). After each one the car tightened up a bit and felt a bit better, but ultimately the braking shake was still there in the car. I also re-built the calipers at the same time I replaced the tie rod ends, in case they were sticking at all (seals / dust boots, etc). I was at a loss.

My next thought was that perhaps one of those suspension parts was loose and was a contributing factor to both sets of rotors going bad, but once the damage was done to the rotors I guess it doesn't go away. So, it's time to try new rotors with all this newly-awesome suspension maintenance. So I pulled the fresh RA rings off the shelf and put those back on the car for a spin. Bedded them in and sure enough got the same vibrational problems....

This is the point where I was about ready to drive the car off a cliff. RA -> Z1 -> RA front rotors all showing the same problem, yet I've swapped everything else that could matter to this up front and that didn't fix it either. Went to (another) front end shop, and relayed the important bits of this story, and asked the guy to dig around for anything but the rotors that could be causing the front end shaky-braking he could obviously feel on the test drive. He inspected / pulled on everything and said, basically, "There's no freaking way your problem is anything but rotors, your suspension is really tight and perfect, and these rotors are bad". WTF. He also took a stab at turning the RA rings, total failure as before, but I'm not yet convinced anyone can successfully lathe a slotted rotor (and to boot, this second set of rings were on a full-float hardware setup, so it was about impossible to lathe on that hub anyways...).

So now we arrive at 3 weeks ago... I ordered another fresh set of Z1 front rotors. Put them on the car, indexed them to 1/1000 or less, mounted everything up, went for a test drive / bedding session (cringing the whole time).. and it went flawlessly. The car felt so straight, smooth, and true under braking I just couldn't believe it. So that last mechanic was definitely right. At that recent point in time, the fresh RA rotors were the only cause of my problems.

Conclusions? - Honestly, beats the **** out of me. I can think of a number of scenarios, all highly-improbable, that match all the data over time above, and I'll list a few of them, but I really don't know.

1) It could be that my suspension and bearings were always good enough to not be a serious problem, and that the first RA rotors, first Z1 rotors, and second RA rotors all had varying degrees of manufacturing issues, taking varying amounts of (in some cases, zero) time to become prominent issues in the real world. Metallurgy, tolerances, etc. And then my second set of Z1's were flawless. Given all my vendor problems with RA, and the fact that he's such a low volume vendor with a semi-shady history I wish I had read up on before doing business with him, I'm totally ready to write off both sets of RA rings as bad-from-the-mfg, but I'm a bit hesitant to write off the first set of Z1s as being bad rotors....

2) It could be that I had a suspension/bearing problem, which would lead to some vibration, which would in turn destroy rotors and make them continue to vibrate even after the original problem was cleared up. This would explain the first set of RA's taking a little while to go bad, the first set of Z1's taking a little while to go bad, but then it doesn't explain the 2nd set of RA's being bad right off the bat on a clean suspension/bearing setup.

3) It could be that the whole original problem was shitty RA rotors, and I had a chain reaction of problems from there. As in: the first RA rotors went bad early due to metallurgy / heat issues, and started vibrating the car badly under braking. During the track event that happened at (some really hard shaky braking hits) + some highway/street miles after, all that shaking from the brake rotors caused premature wear and looseness in ball joints and/or tie rod ends and/or bearings, which then lead to that being the issue that appeared and damaged the Z1's while they were on the car. Then I cleared all of that up, and the second set of RA's was bad from the get-go, and the fresh Z1s on completely cleaned up suspension/bearings was fine.

Right now the car feels perfect, I've even gone out in the middle of the night and done some track-level braking tests, and it's flawless on the Z1's with all the new suspension/bearing bits in place. One week to my next track event (after having cancelled a few over the past few months due to all of this ), so the real question is whether the problems are gone for good after another track weekend or two. Time will tell.

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wstar

Funny/sad after-note: Now that everything seems ok, I decided to clean my pile of used rotors out of the garage, it was getting kinda excessive. Piled them all up and took em to a recycling place. From my old stock rotors up through all the others I burned through in this process, I ended up with ~240 lbs of scrap iron, got $21 from the recycler. That's after, what, I donno, something like $3.5K down the drain on all of this over the past year between rotors and suspension parts, untold hours and hours of my labor in the heat over numerous weekends, and 4 missed track weekends (including two I paid for and had to cancel out on).

In the net, I can't say anything conclusively. There was too much noise in all the debugging process to know for sure. I wouldn't recommend RA to anyone though, it's totally not worth it.

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Journal thread / Car setup details

Jsolo

Wow... Quite the saga with rotors!

I would bet that with a full stock setup, there is enough give in the entire system to mask any minor runout. Upgrade to all high performance parts and any deficiencies start to become apparent.

I noticed this to some extent when doing the brakes on the bike, one part at a time. Swapping SS lines for stock (dual run direct from the master to each 4pot caliper) resulted in minor difference. Felt very similar to stock, had ever so slightly (placebo?) harder lever. Some months later, replaced OE pads with EBC HH compound pad (somewhat high performance), bled the system again. This time, the difference was profound. The lever had very little movement to it before becoming rock hard. Practically no sponginess at all. Better feel/feedback as a result. I used the same type of fluid for each bleeding/flushing event. The only change was the pads. OE pads still had about 40-45% material left.

No desire to be tracking the car, but better pedal feel and better initial bite are welcome upgrades from the stock setup. Probably go with some sort of higher performance pad (stoptech performance street pad and SS lines all around) at some point.

Mike

I had the same problems, with Z1, Centric and one other brand of rotors. All of my problems went away when I switched to the stoptech brake kit. I would get about two track days before the steering wheel would start shaking on braking.

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wstar

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.

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Journal thread / Car setup details

wstar

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 .

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.

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wstar

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

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ChrisSlicks

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.

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Hotchkis ARB | Stillen CAI | Art Pipes | Berk CBE | Stillen AP Racing Brakes | AE Performance Oil Cooler | BC Racing ER Coilovers | Doran Control Arms

SPOHN

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!

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ChrisSlicks

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.

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wstar

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

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ChrisSlicks

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).

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Hotchkis ARB | Stillen CAI | Art Pipes | Berk CBE | Stillen AP Racing Brakes | AE Performance Oil Cooler | BC Racing ER Coilovers | Doran Control Arms