After my last trip to Thunderhill, my stock rotors (C6/F55, no slots/holes) look like they've been put in a blast furnace then dipped in cold water . . . got that splotchy, heat-treated look instead of the stock polished look. Fronts and Rears. They're also a bit pitted (that's interesting, what causes that?). Pads are still serviceable, so there's no scoring. I don't think there are any fractures. As I said in a previous post, I found the brakes (finally) on track day and have every intention to fry them again every chance I get!
Here's the question(s) . . . Is this typical of severe use, and what pads and replacement rotors do ya'll suggest for a weekend warrior (road course only). I don't care about pretty (although that's OK). I'm looking for decent function that's not terribly expensive but clearly consumable/expendable. No real plan to replace the stock calipers . . . don't want to get too crazy with this new habit. And, should I replace the brake lines with SS?
Oh, BTW, I've been leaving AH and the TCS "on". I'm probably not doing myself or my brakes any favors with the TCS ON at this stage in my education. I'm betting my brakes are getting worked harder than I realize.
While I'm at it . . . any recommendation on a street-legal tire that's best on the track? I don't have any plans to trailer my ride, so it'll be taking me to and from the track as well.
I'm running Performance Friction Z-Rated street/track pads and the front rotors are also from Performance Friction, just slotted not cross drilled. I put on Baer Eradispeed Cross Drilled and Slotted rotors in 2003 and the fronts developed stress cracks around the holes last spring. The setup I have now is awesome, once they heat up, usually takes almost 2 laps. If I push it before they warm up I almost visit the dirt on turn 5.
As for tires, I used to track with Michelin PS2's, great tire but kinda expensive. Before that I had F1 Supercars - both are awesome on the track. The PS2's take a little longer to hookup than the F1's and took a while to "trust" the tires. PS2's are a lot better in the rain. I run Kuhmo's on the track now and they are great, also DOT certified. I have another set of wheels with the Kuhmo's and just swap out before and after track events. The HPDS in october (garbage truck day) I had the PS2's on because it was so wet out.
I have a friend with a Cadillac CTS-V that tracks his car and he runs Nitto NT-01's. A little more "tread" (grooves in the slicks) than the Kuhmo V710's I have and he drives to and from the track all the time. Don't know if they come in your size.
As your comfort level increases you want to expect the rotors to have short lives. Cracks close to the edge and they should be replaced, until then your golden. I would go with more aggressive pads for just track days unless someone can recommend a nice, low dust, all around one. I run PFC-01 upfront and unless warmed up and hot, you don't want them on. Sounds and feels like metal grinding.
As for tires, I’ve had the Michelin PS2s, and while they are a good street tire and wear well, I found they don’t grip very well compared to softer compound tires. Surprisingly, the best set of tires I’ve ever had for street/track combo use were Sumitomo HRZ II. http://www.tirerack.com/tires/tires....Model=HTR+Z+II
And they were REALLY cheap – About $600 for a set of for (in C5 sizes), including tax, mounting and balancing, if I remember correctly. I bought them at Roger Krause Racing in Castro Valley. Tire Rack also carries them.
But with that said, if you ever get the chance, a set of track tires makes a HUGE difference. I use the Hoosier R6, and get about 4-6 track days out of a set. http://www.tirerack.com/tires/tires....r&tireModel=R6
But then you do have the hassle of hauling them to the track and switching them out.
As for rotors, I’ve only had C5s, so I’m not sure about the C6. But I found that the cheapo rotors from either Napa Auto Parts or Monument Auto Parts held up the best. Monument Auto Parts seems to be more consistent as far as keeping them in stock. And at less than $30 a piece, they’re just about throw-aways. I always take an extra set with me to the track. That’s a bit more pricey to do if you’re running expensive Brembros, or the like.
And a set of race pads will also make a HUGE difference. I use CarboTech pads – XP12s on the front and XP10s on the rear. http://ctbrakes.com/pads/chevy.html They run about $400 for a full set. MSI in Roseville keeps them in stock. I usually just call them and have them shipped.
Good luck! And enjoy the addiction!
Hope to meet you in person at the track one of these days.
Thanks guys. Exactly the kinds of info and advice I'm lookin' for.
Here are some pics of my rotors (15K mi, 2 trips to THill). Lots of surface anomalies. Don't remember seeing these when they had that nice chrome-looking sheen. And notice the tempered appearance. Is this typical of rotors that have seen some serious use? I've looked as close as my old eyes will allow and I don't see any fractures, but would I recognize it if I saw it? There are some marks that almost look like scoring, but there is still lots of pad left on all 4 corners. And look at the oxidation. That definitely wasn't there prior to my last trip to THill. I assume that's another sign these babies have been very hot. Again, just curious. I realize rotors are disposable.
I'm thinking I need a set of street rotors to keep the car from looking like a rust bucket, and a set (or ten) of rotors for the track that I don't care what they look like as long as they perform. Same with the pads I suppose.
It looks like a non uniform film of friction material could of deposited on the rotor due to overheating. I think a change to higher temperature pads are needed.
Fred, all good inputs above, everyone finds what works best for them. I
agree with Sidney that the visual signature is pad material, most likely,
and since uneven it might be from not getting cooled enough before you
park or things as simple as parking the car after washing. There are
some writeups that are good on the StopTech site as I remember.
The track tire options come in about three flavors, I run 220 wear rating
Kumho MX's, one of the pretty cheap options and true street tire. Then
there are the close to 100 wear rating tires and I think that the NT-01
fits there. It has some tread for the top 3mm but then is just like a
DOT-R with only twin grooves. The twin groove, 40 wear rating, DOT-R's
will get you to the track and back in the dry but pays to be very careful
when they are cold.
As for running AH in Comp mode, with TC off or with TCS on, just remember,
I was coaching two different guys at Spring Mt. recently and they both
had the system on and each had a major slide and off. It won't save
everything! As for wearing the brake pads, the smoother you are the
less it wears them, turns out in the long run that smooth is fast, so
it pays off there too.
Randy
I agree with Sidney and Randy - Your pics look like pad material transfer on the rotors. It just looks like your pads were overheated (for the material they are made of). Using a higher heat-rated pad should eliminate that. Make sure you bed new pads in, and re-bed them if you're switching from one pad to the other. Bedding them in actually transfers a uniform layer of pad material onto the rotor, which is what you want for maximum braking affect.
And Arnel is right about not wanting to use race pads for street use. They're very noisy and dusty.
As for cracks in the rotors, they are hard to see on the face of the rotor. They are much easier to spot by looking along the outer edge of the rotors (the rusted edge that does not contact the pads). The cracks show up pretty well in the rusted surface.
I remember my first time at the track - I went through a brand new set of street pads in a day and a half, and cracked 3 of my rotors (drilled & slotted). In time, as Randy mentions, I learned to be easier and smoother on the brakes. Smoother really does translate to faster. It's more about weight transfer and keeping the car in balance, than charging into corners as fast as possible (which is what I did at first).
Oh, and as I found out, drilled rotors are NOT a good thing for track use. The holes just give cracks a good place to start.
Another comment on rotors. NAPA recently charged me something in
the mid $40 range vs. the $26 I was used to. I still got a set from my
service guy through his parts source in the 20's but I think that may
be drying up.
Randy
Another comment on rotors. NAPA recently charged me something in
the mid $40 range vs. the $26 I was used to. I still got a set from my
service guy through his parts source in the 20's but I think that may
be drying up.
Randy
Randy,
Try the Monument Auto Parts store in Pachecho. That store seems to keep the C5 rotors in stock. Not so much the case for their other stores for some reason. I think they're Raybestos brand and only $29 each last time I bought a set. I think they have another brand for about $40 each, which is what they give you unless you ask for something else. So I always ask for the cheapest ones they have. I had them on the green C5 (Kermit), as well as on the GTR. They held up very well.
Seems like every time I called Napa Auto Parts no one had them in stock - Had to special order.
If you want...I have set of Base rotors only used 5k miles of street driving. Free
Shalen:
Great to meet you yesterday. I'll never beat that deal, nor the price of delivery! Thanks a million (or at least a few beers worth!). After all the car-talk (and a peek at weather.com), I just had to get the beast out of the garage this AM. You've got one sweet ride. I want your Kooks and your Corsa's BAD!
I'm going to get some decent street pads and then swap my rotors out for yours (mine ). Night and day visual difference. I clearly burned the zinc off of mine. But I had a blast doing it!
If mine aren't fractured and I can get someone to turn them down for cheap, I may attempt to get another track day or two out of them. I'm inclined to agree with the "deposit" theory. Another friend at work suggests the minor scoring could be from track debris. Regardless, it seems unanimous that I took my pads beyond their designed use.
Fred, all good inputs above, everyone finds what works best for them. I
agree with Sidney that the visual signature is pad material, most likely,
and since uneven it might be from not getting cooled enough before you
park or things as simple as parking the car after washing. There are
some writeups that are good on the StopTech site as I remember.
The track tire options come in about three flavors, I run 220 wear rating
Kumho MX's, one of the pretty cheap options and true street tire. Then
there are the close to 100 wear rating tires and I think that the NT-01
fits there. It has some tread for the top 3mm but then is just like a
DOT-R with only twin grooves. The twin groove, 40 wear rating, DOT-R's
will get you to the track and back in the dry but pays to be very careful
when they are cold.
As for running AH in Comp mode, with TC off or with TCS on, just remember,
I was coaching two different guys at Spring Mt. recently and they both
had the system on and each had a major slide and off. It won't save
everything! As for wearing the brake pads, the smoother you are the
less it wears them, turns out in the long run that smooth is fast, so
it pays off there too.
Randy
Thanks. Do you suggest a moving cool-down after coming off the track? At least once the black flag came out while I was deep into the throttle approaching 14, so it was hard on the brakes and then right to the pits and park.
Smooth . . . check. A Jackie Stewart trademark. Dom was all over me for upsetting the car too much turning in on 5 . . . and everywhere else for that matter. So, my brain knows, if I can just get the hands and feet to comply. I think I'm doing OK for a noob with my steering inputs, but brakes and throttle are still a mystery . . . all in good time I suppose.
Thanks guys. Exactly the kinds of info and advice I'm lookin' for.
Here are some pics of my rotors (15K mi, 2 trips to THill). Lots of surface anomalies. Don't remember seeing these when they had that nice chrome-looking sheen. And notice the tempered appearance. Is this typical of rotors that have seen some serious use? I've looked as close as my old eyes will allow and I don't see any fractures, but would I recognize it if I saw it? There are some marks that almost look like scoring, but there is still lots of pad left on all 4 corners. And look at the oxidation. That definitely wasn't there prior to my last trip to THill. I assume that's another sign these babies have been very hot. Again, just curious. I realize rotors are disposable.
I'm thinking I need a set of street rotors to keep the car from looking like a rust bucket, and a set (or ten) of rotors for the track that I don't care what they look like as long as they perform. Same with the pads I suppose.
Thanks again . . .
FM
I'm almost positive that it is pad material, and that you could prevent this from happening by just changing the way you park the car in the paddock.
When you finish a track session and park in the paddock, you do not want the pads resting against the hot rotors. It causes what you see on the rotors, but it also causes things that are harder to see. Your rotors can warp or even crack, due to uneven cooling. Also the rubber seals on your caliper pistons can be destroyed when the heat of the rotors seaps into the pistons.
To finally stop the car in its parking place (to slow it from about 1 mph to the final stop), do not use the brakes. If you use the brakes that last time, then the pads will remain firmly against one spot on the rotors until you decide to move out of the parking place, and you'll likely cause some or all the above damage.
What you need to do is:
1. Of course, use the brakes to slow the car down in the paddock, including getting it slowed way down just before parking it.
2. Slowly roll up to your parking place in first gear.
3. Release the clutch and kill the engine just before you turn into your parking place. If you still think you're going too fast, then use the brakes to slow down to less than 1 foot per second. Try to let the car roll with no brakes for at least the last 3 to 5 feet.
4. When you're almost in the final position, then release the clutch (transmission still in first gear) to let the dead engine stop the car.
Bob's advice on getting the car to stop with the pads not in contact
with the rotors is spot on. Lot's of groups are now going to 1/2 lap
checker's and it pays to take it easy around the paddock once just to
get some cool air around the brakes. You also might watch the temp
of the coolant on that lap, at least mine with an old stock radiator, goes
up as I'm driving with the wind and then goes back down as I turn
around and go into the wind, astounding how much difference it makes.
You may be surprised but at the beginning you really aren't stressing
the whole package much. I used to get oil temps up in the 250's at
Sears Point then it went to 270's and finally before I got a cooler it hit
295 one day about a year into doing track days. Just keep an eye on
things like you are doing and you will sort it all out as needed.
Randy
Bob and Randy . . . thanks. Makes all kinds of sense. In fact, in that last rotor photo you can even see the negative of the gap between the pads superimposed on the rotor . . . thought it was my imagination until now. I'll definitely follow your stopping advice. First time I heard the park brake story it made sense, so I've not made that mistake.
I've been concerned about oil temps on this car from the beginning. In normal, low RPM summertime highway driving I was seeing as high as 240s. Get on it a bit and I'd see 250s. Coolant temps hovered just a bit over 200. Rick at Synergy didn't seem concerned, but recommended I change (all my vehicles, in fact) to 10W30 and put in a 160 TStat, both of which I've done. Of course he changed the fan. Magically my oil temps dropped (this was back when ambient daily temps were still in the 80s and 90s). My research says he's right about the oil for this area, at least for highway miles and a garage-kept car. But I can't explain the dip in oil temps. Even on hot ambient days I started seeing 220s as the norm with 230s under "spirited" conditions. Regardless, I've seen 260s on the track, but it's been relatively cool both times I've been to THill. Coolant temps on the highway are also generally lower, staying at or just below 200. I don't remember what they were on the track. We'll see if this holds when the weather heats back up next summer.
BTW, do you use a different viscosity for the track?
Thanks so much again guys. I've had so much fun at the track I'd continue to go back regardless of my progress, or so I think. But I don't want to hurt the car out of ignorance.
Because of the high oil temps I see on the track, I use 20W50 for track days, especially in the summer. 250's to 280's is not unusual for oil temp at the track, depending on how much you're pushing it and on the ambient air temp.
Also, the more HP you're pumping with various engine mods, the more heat you'll see. My stock C5 ran all day long and would barely reach 250's on the oil temp. But the GTR, with a 382 stroker at about 11:1 CR, would easlily run up into the 270's+.
Corvette Store
Advice on brakes . . .
). Night and day visual difference. I clearly burned the zinc off of mine. But I had a blast doing it!
