I just got back from my first open track day with my Z06, which performed very well for a bone stock car with one exception.....I have a radial crack in my left rear rotor that goes completely through the outer face. I am new to the Z06, but not to track driving/club racing. I was using PFC 01/99 pads and Motul 600 fluid, and was at a Carolina Motorsports Park in Kershaw SC. It was a race weekend for the World Cars series, and I was getting open track time between thier race practice....I ran mostly 15 min sessions, but also a few 20-30 min sessions as well. Just wondering if you serious track junkies and T1 racers have had similar problems with the rear rotors, and what to do to prevent it from happening again. I fully expected to get some small stress fractures especially in the front rotors, but this is crazy.
Needless to say I need a pair of stock rear rotors ASAP....anybody know the cheapest place for OEM replacements?
I'm sure you know you probably couldn't have picked a track that is any harder on brakes than CMP. I have run there once with my '02. Didn't have any serious problems with the brakes but did experience some fade. Frankly, oil temp was a bigger problem for me (at CMP and elsewhere); running up close to 300 degrees and had to come off the track to let it cool (have since purchased an oil cooler but not yet installed). I was running the stock pads - that could be one of the reasons for your issues. I'm sure the ones you were running have a higher coefficient of friction than the OEM pads. I will likely add some cooling ducts to the front rotors ala the kind DRM sells on it's web site to help reduce fade and improve reliability. I have also heard GM has a set of "Grand AM" rotors for this car that are a little thicker and resistant to fade although I haven't heard of anyone with experience with them.
After a couple months of ownership, I think brakes would be one of the things I wish GM would improve. I wouldn't care if the price of the car went up by $1-2K, I'd much rather have brakes that performed like a 911. The other thing I'd like to see them improve would be the seats.
Yeah, CMP oughta hand out pads and rotors as door prizes!!
I swore I’d never return when I fried a set of $2800 AP racing brakes there when I had a 3rd gen Rx7, but I have recently been several times in a spec miata which makes you forget about ever having brake troubles.
Anyway, I appreciate the feedback. I tried to get the DRM ducts before going to any track, but they are backordered for a few weeks as the T1 guys wiped them out.
It was a relatively cool day yesterday (80-85F) and I was able to keep my oil temps around 265F by short shifting at a few places.
I would love for someone to build a set of rotors similar to eradispeeds (aluminum hat with replaceable rotor) with full emphasis on track use. I would think a similarly sized Coleman or AP rotor on an aluminum hat would have the potential to absorb more heat without cracking to pieces.
Not bashing the eradispeeds as I have not heard from a serious track junky about their abilities vs. stock rotors, but the drilled rotors give me an uneasy feeling.
Dilusi makes what looks to be an interesting solution…..anybody tried their stock size replacements?
I may just have to stick to the more brake-friendly tracks for awhile
Wow,
That event looks like a pretty good deal. I may be up for the Fri. lapping day. Can't beat all day for $100....just gotta watch that left front tire, as RR will tear it up.
I ran -2.25F camber at CMP and still got some uneven outside edge wear, but I am sure the street driving will even them out....they will end up bald on the inside and outside with plenty of tread in the middle
If you're going to sign up, do it quickly. The coordinator told me it was filling up fast. I sent my app. in early last week and I'm not 100% sure I got in. It's a great track though. If I get in I will sign up for the lapping day as well - maximizes your weekend bang for the buck.
The Z06 Brakes.....ARE the weakest link.
The stock rotors are relatively cheap and most T1 guys consider them disposable items changing them after 1-2 races.
You are on the right track with the Motul 600 and the Pfc o1's. As to the rotors I might suggest having the new ones Cryo treated. This will help them not to stress/heat crack and will add some life. 50%. It will also increase their performance slightly. You might also have grooves ball milled into the rotor faces.
I am concerned that th e rear has a lrge crack and the rea cracked first. I am thinking it was the outside rear and had more stress on it. Rotors can be cracked also from an uneven mounting/mating surface(s). Make sure when you put the new ones on that the hub, both sides of the rotor and the wheel rim surface is clean and pristeen. Rotor cracks can also develope from incorrectly torqued wheel nuts. Don't overtighten. Torque using a "star" patern and use a step method per factory recommendations. Do not use an air impact wrench and Hand torque with a good 1/2" drive torque wrench.
Of course you may also have heat problems. Make sure the brakes are vented and nothing is in the ducts or covering the vent.
You can also change the stock Aluminum Caliper pistons to Stainless Steel Ones. Doug Rippie has them. But they are heavier. Vette Brakes and Products will redo your calipers with Titanium ones or you could have Titanium ones custon made. Both SS and Ti will not conduct heat to the rotors and wheel hub/bearing as Al will. You might also try Ti or Ceramic pad backing plates or pads with integral non-conductive backing plates built in.
Thanks for the input DJWORM.
I agree with everything you have stated(proper lug torque, proper tightening sequence, ect) and all of this was done. I do consider rotors relatively cheap consumables on any track driven car, but I do not expect them to come apart in only 100 track miles.....this rotor does not just have surface stress cracks (normal) but from the outside it looks almost cracked in half.
I am actually wondering if it is not a manufacturing defect or if maybe the rears were cooled to quickly on my cooldown laps (one or two laps without brakes at all.)
I am actually surprised that I didn't have any other issues with fade or brake fluid boiling. This track is really tough on brakes, and since I didn't have any fluid boiling issues there, I am going to wait on the SS pistons or ceramic backing plates.
I would love the DRM 4-wheel AP brake setup....dang, I would even settle for a measly set of Stoptechs
Just not ready to give up on the stock setup yet.
FYI - a buddy of mine tried the frozen rotors on his 1988 911 and first time out at CMP, he warped them badly. I'm not sure it's really worth the extra $$. Also when he called to check on the guarantee, they were only willing to refund the cost of the cryogenic treatment, not the full cost of the rotors. Given the relative pittance they offered him on a refund, I have to assume they're not adding much value in the treatment.
I am not really keen on the frozen rotors myself, as cryo just seems like vodoo magic to me at this point. I would rather just bring an extra set with my to the track. I actually have a really good hypothesis formulated at this point from advice from another forum. Here goes:
I had the car in Competition Mode all day at the track, as it didn't seem to kill my fun, and actually saved me from having a "moment" a few times. I activated the Active handling several times per lap, which may have contributed to the increase rear rotors temps. I guess that the rear brake were working overtime to keep the wheelspin down
Hey, it is as good of a theory as proposed so far....
Makes sense in that my front rotors, pads, dust boots, and tie rod ends all looked really good when changing out pads today, but the rear rotors and pads looked kentucky fried.
Often when a rotor cracks all the way through (single crack, not hairline), it is found to be a bubble or debris in the casting. Take a careful look at it. If you find such a defect, GM might give you a new one. Ford does if you argue...
I guess if you are hardcore, you could X-ray or magnaflux for defects prior to install, but unless you're racing for money, I wouldn't.
Been there done that. On my third set of OEM rotors. Let's face it the OEM Rotors are junk. But, I am cheap and in the long run the OEM rotors, which you can get for 55 a piece, are cheaper then the fancy cryo BS stuff. Metal is Metal and it is going to crack and wrap after a number of heat cycles. Yes cryo treatment prolongs the rotor life, but it will crack and wrap like any other rotor under a lot of heat stress. My structure prof in college use to call metal like you are lead to believe what the cyro treatment will do for it, un-atain-ium. Cause it is not on this planet.
If you talk to the guys who run SCCA T1. A lot of the front runners use the OEM rotors and replace them like brake pads. I have friend I run at the track with and they have tried the fancy BS stuff only to go back to the OEM rotors because of cost in the long run. I can see if you have a lot of money on the line for a race then you want every edge you can get.
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