wstar's Journal

Equinox · 04-18-2012, 01:55 AM

Oh gawd I forgot about how awesome J hook is as a concept. I need some for my 911 o.o

wstar · 04-24-2012, 01:59 AM

Just wrapped up a fun weekend at MSR Houston. Brakes were a non-issue functionally, and the new front ducts from Stillen worked out well.

As for the new Z1 rotors: mostly, they bedded and operated flawlessly. One of my rears, however, had some visible heat cracks in it starting from right after my first session. They were pretty shallow and not causing any big surface effects, and I didn't feel any braking problems from it. Over the course of the remaining sessions the crack landscape on that rotor evolved: wear would erase a few, expand a few more, then erase those, etc.

I'll have to inspect super-close tomorrow, but probably most of the cracks are gone now, I don't think any were very deep. I suspect the cause is that the cross-hatch pattern (that they lightly etch into the surface to help initial bedding) was accidentally cut a bit too deep on this one rotor, as it took forever to wipe out those cross-hatches on just this one rotor as well. The matching rear rotor on the other side killed its cross-hatch pattern much faster and never developed any visible cracks.

Still pretty happy with them though, I think this was just a one-off QC issue, and the price is awesome.

I got to do a few solo sessions this weekend. I'm not "solo certified" with this group yet, but I guess they're giving me a few test sessions to see how I'm doing on my own, and I did fine. All in all, I think it was a really good weekend skills-development-wise. My traffic management and general "awareness" downtrack and to the corner workers is getting better, finally getting myself to lift my head up a lot more. Starting to get a much better feel for the edge of traction, and getting better at car control. My lap times were "meh" most of the weekend, because I trying to focus on problem areas and taking it easy in others.

Still having psych issues with fear management getting the better of my lines and throttle input in places, especially The Launch (the big hill in the track you'll see in the vid). I know in my head the right way to go over that is to be on full throttle before, during, and after it, but convincing my gut that it won't lead to a nasty off-track excursion is hard. I ended up holding back on a weak/stable throttle and easing through it every damn time most of the weekend. Finally got over it at full throttle on my last session, and wished I had done it sooner

.

Anyways, I only put a couple laps up on Youtube. These are from a solo session back on the first day. Lots of mistakes to focus on for next time

wstar · 05-02-2012, 04:44 PM

A few new pics from this past track weekend. This is a decent one of the car:

And this is my favorite from the weekend. If you look closely, I just passed a ZR1 Corvette (because he spun out not far in front of me, so it was the only chance I got all weekend :P)

Huck · 05-09-2012, 12:39 AM

^^ these look great! and I liked the video too. I would love to track my car, but I don't have the money needed to be competitive like I would be, and I'm like 2 hours from the nearest track, so I guess I'm stuck with the 1/4 mile, huh? Keep at it!

wstar · 05-09-2012, 01:26 AM

It does get a little expensive. I'm not made of money either though, it's just all about priorities. Sell a kidney, get another track weekend paid for, that kind of thing

Huck · 05-12-2012, 01:35 AM

Damn it, I'm fresh out of kidneys, and my body can make blood and semen to be sold only so quickly. What else can I do??

Sent from my iPizzle using magic and new fangled science stuff

SPOHN · 05-12-2012, 07:11 AM

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.

sixpax · 05-12-2012, 07:40 AM

Quote:

Originally Posted by wstar

It does get a little expensive. I'm not made of money either though, it's just all about priorities. Sell a kidney, get another track weekend paid for, that kind of thing

...LOL. Funny how that works. I only did one Hyperdrive (similar to a single HPDE-1 session) and I am already looking around for what I can sell, working a little OT which I have not done in 10 years, anything to get some extra cash to keep the wife happy and make the car better so I can go back. At least I know the "addiction" part seems to be fairly common.

I looked into the kidney thing, would only cover 1 weekend so I think I will keep it for now.

Nice video and pics !

wstar · 05-12-2012, 11:31 AM

Quote:

Originally Posted by 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.

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

.

Jsolo · 09-01-2012, 01:59 AM

Quote:

Originally Posted by wstar

Being paranoid about wasting any further track weekends on unexpected brake issues, I was extremely analytical and careful with the new rotor installations. I took dial-gauge runout reading on all 4 rotors and thickness variation data, etc, and did some indexing of the mounting rotation offset to minimize the runout. Everything's way way below OEM spec limits. My worst corner is at .004" runout prior to bedding measured all the way out at the edge, and even that I think was reduced slightly with the wheel torqued on top (as opposed to lightly torquing lugnuts onto the brake rotor itself when measuring). The OEM spec limit is .014" a bit in from the edge (center of pad swept area, basically). So, measurably, these are good rotors in manufacturing quality terms.

Sorry to bump up an old thread, but can you confirm the spec above? According to the FSM for the G (which uses the same 4 pot brakes as the Z), the spec is .035mm or .0014" - that's 14 ten thousandths of an inch, not 14 thousandths.

The FSM does show a THICKNESS variation of .015mm, so maybe that's where you got the # from?

Anyhow, .0014" is pretty damn small, barely the thickness of that thermal receipt paper.

wstar · 09-01-2012, 09:41 AM

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.

wstar · 09-01-2012, 11:04 AM

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.

wstar · 09-01-2012, 11:23 AM

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.

Jsolo · 09-01-2012, 11:59 PM

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 · 09-02-2012, 07:00 AM

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.

04-18-2012, 01:55 AM	#481 (permalink)
Equinox Track Member Join Date: Jul 2009 Location: Beaumont, TX Posts: 685 Drives: 06 Porsche Carrera S Rep Power: 18	Oh gawd I forgot about how awesome J hook is as a concept. I need some for my 911 o.o __________________ Check out my Albums '13 Subaru WRX STi \| '06 Porsche 911 Carrera S (SOLD) \| '96 Mazda RX-7 6.0L V8 RHD (SOLD) \| '09 Nissan Nismo #0058 (SOLD)

04-24-2012, 01:59 AM	#482 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	Just wrapped up a fun weekend at MSR Houston. Brakes were a non-issue functionally, and the new front ducts from Stillen worked out well. As for the new Z1 rotors: mostly, they bedded and operated flawlessly. One of my rears, however, had some visible heat cracks in it starting from right after my first session. They were pretty shallow and not causing any big surface effects, and I didn't feel any braking problems from it. Over the course of the remaining sessions the crack landscape on that rotor evolved: wear would erase a few, expand a few more, then erase those, etc. I'll have to inspect super-close tomorrow, but probably most of the cracks are gone now, I don't think any were very deep. I suspect the cause is that the cross-hatch pattern (that they lightly etch into the surface to help initial bedding) was accidentally cut a bit too deep on this one rotor, as it took forever to wipe out those cross-hatches on just this one rotor as well. The matching rear rotor on the other side killed its cross-hatch pattern much faster and never developed any visible cracks. Still pretty happy with them though, I think this was just a one-off QC issue, and the price is awesome. I got to do a few solo sessions this weekend. I'm not "solo certified" with this group yet, but I guess they're giving me a few test sessions to see how I'm doing on my own, and I did fine. All in all, I think it was a really good weekend skills-development-wise. My traffic management and general "awareness" downtrack and to the corner workers is getting better, finally getting myself to lift my head up a lot more. Starting to get a much better feel for the edge of traction, and getting better at car control. My lap times were "meh" most of the weekend, because I trying to focus on problem areas and taking it easy in others. Still having psych issues with fear management getting the better of my lines and throttle input in places, especially The Launch (the big hill in the track you'll see in the vid). I know in my head the right way to go over that is to be on full throttle before, during, and after it, but convincing my gut that it won't lead to a nasty off-track excursion is hard. I ended up holding back on a weak/stable throttle and easing through it every damn time most of the weekend. Finally got over it at full throttle on my last session, and wished I had done it sooner . Anyways, I only put a couple laps up on Youtube. These are from a solo session back on the first day. Lots of mistakes to focus on for next time __________________ 7AT Track Car! Journal thread / Car setup details

05-02-2012, 04:44 PM	#483 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	A few new pics from this past track weekend. This is a decent one of the car: And this is my favorite from the weekend. If you look closely, I just passed a ZR1 Corvette (because he spun out not far in front of me, so it was the only chance I got all weekend :P) __________________ 7AT Track Car! Journal thread / Car setup details

05-09-2012, 12:39 AM	#484 (permalink)
Huck A True Z Fanatic Join Date: Jan 2012 Location: Cocoa, Florida Age: 42 Posts: 5,075 Drives: Pantydropper machine Rep Power: 33	^^ these look great! and I liked the video too. I would love to track my car, but I don't have the money needed to be competitive like I would be, and I'm like 2 hours from the nearest track, so I guess I'm stuck with the 1/4 mile, huh? Keep at it! __________________ VLEDS \| Evo-R \| Moddiction \| CF Hood Struts \| F.I. CF CBE & LTH \| Stillen CAI \| NST Pulleys \| UpRev \| Z1 \| M7 \| Status \| Forgestar \| PSS \| Whiteline \| SPL \| SPC \| Kenwood \| Zenclosure \| Kicker \| Alpine Type R

05-09-2012, 01:26 AM	#485 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	It does get a little expensive. I'm not made of money either though, it's just all about priorities. Sell a kidney, get another track weekend paid for, that kind of thing __________________ 7AT Track Car! Journal thread / Car setup details

05-12-2012, 01:35 AM	#486 (permalink)
Huck A True Z Fanatic Join Date: Jan 2012 Location: Cocoa, Florida Age: 42 Posts: 5,075 Drives: Pantydropper machine Rep Power: 33	Damn it, I'm fresh out of kidneys, and my body can make blood and semen to be sold only so quickly. What else can I do?? Sent from my iPizzle using magic and new fangled science stuff __________________ VLEDS \| Evo-R \| Moddiction \| CF Hood Struts \| F.I. CF CBE & LTH \| Stillen CAI \| NST Pulleys \| UpRev \| Z1 \| M7 \| Status \| Forgestar \| PSS \| Whiteline \| SPL \| SPC \| Kenwood \| Zenclosure \| Kicker \| Alpine Type R

05-12-2012, 07:11 AM	#487 (permalink)
SPOHN A True Z Fanatic Join Date: Feb 2010 Location: Covington, GA Age: 45 Posts: 14,844 Drives: Waiting on next Z Rep Power: 221	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. __________________

09-01-2012, 09:41 AM	#491 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	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. __________________ 7AT Track Car! Journal thread / Car setup details

09-01-2012, 11:04 AM	#492 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	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. __________________ 7AT Track Car! Journal thread / Car setup details Last edited by wstar; 09-01-2012 at 11:38 AM.

09-01-2012, 11:23 AM	#493 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	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. __________________ 7AT Track Car! Journal thread / Car setup details Last edited by wstar; 09-01-2012 at 11:39 AM.

09-01-2012, 11:59 PM	#494 (permalink)
Jsolo Track Member Join Date: Dec 2011 Location: chicago Posts: 783 Drives: '12 G37 6MT Rep Power: 14	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.

09-02-2012, 07:00 AM	#495 (permalink)
Mike The370Z.com Sponsor Join Date: Jun 2009 Location: Loganville, GA Posts: 5,944 Drives: 370z Rep Power: 2186	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. __________________ NISSAN: 75 280Z / 86 300ZX GLL /87 Sentra SE / 03 350Z / 23 Z Porsche: 93 968 / 23 Macan GTS / 93 968

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