Getting ready for a day at VIR tomorrow. I drive pretty hard at the limit in the intermediate class, but still on streetable tires (Nitto Neo Gen 215/45R17 currently) and OEM brakes with Carbotech XP10/XP8 pads. One thing I'm still trying to figure out is tire pressure... I have a pyrometer and a good pressure gauge, and tried to use them last time at the track. I understand the concepts behind the impact of low and high pressures on temps across the tread, and impact of pressure on tire stiffness. I experimented with a pretty wide range of pressures last time, but still spent most of day cornering on my sidewalls and wearing the outside shoulders off my tires... Any general pointers you guys with more track experience can give me about what my cold and hot target pressures should be on these (or similar) tires? I'm just trying to figure out where my starting point should be. I've heard folks say I should be starting anywhere from 25psi to 50psi... obviously that hasn't helped... :mad2:
OK... so I've read a little more on this... 1) in case you need to know... I'm running about -1.8deg camber F, -1.2deg R 2) Koni FSD's, Ireland fixed plates, TSW springs, H-Sport 19mm swaybar (medium setting), H-sport lower control arms, TSW endlinks set for no preload with driver in car. While I know I can do MUCH more experimenting with pressures tomorrow, and maybe need to start with something like 40psi hot as a starting point, I'm probably driving beyond the limit of these tires at my current camber settings and need to slow down vs. drifting like mad out of every corner... I'm probably pushing way too much slip angle for these tires... Thoughts?
I would like to see some input on this too. I know how I used to run my 67 Alfa GT on R1s, but the R56 on the track is a little different for me. Currently on casual lapping I'm leaving my 16" F1s at 36 all the way around, but not aggressive driving, pretty much moderate lapping. I imagine tire setup between the R53/R56 and Cabrio might be different. Don
40 hot is what I've had recommended to me, and it works as a pretty good starting point. I usually start around 32-33 cold, then adjust as the day goes on depending on how the day is going. I usually wind up going a little higher on the rears than the fronts...
I run the cabrio top-up at the track. With the top down, it's significantly more rear-heavy - you can visibly see the difference in ride height with the top up vs. down. It's still a little more rear-heavy than the coupe even with the top up due to the convertible mechanism and under-chassis bracing. But I haven't corner weighed it to see what the weight distribution really is.
+1 on top up at the track. i like top down at autocross. optimal tire pressures seem to be unique to the tire. for my direzza star specs, i used to try to keep them at 38 when warmed up. i didn't really care for the ride above 42. i now have bridgestone re-01 pole positions and am not sure where their sweet spot will be. it may be a case of trial and error for us all. i did find a lot of info on the star specs on nam that was helpful....so when you find your sweet spot, please post it! have fun and be safe!
+1 for the 40 psi hot tire pressure. I have run Dunlop Direzza Star specs, Falken Azenis and Hankook RS2's and the 40 psi has generally served me well. The first run of the day I start at 35 all the way around. Depending on how your car rotates you will want to adjust the rears appropriately. Higher for more rotation, lower for more grip. For reference, I am running TSW KW V2's with a 19MM rear sway on the middle setting. 2.4 neg camber up front, 1.5 neg in the rear and have had the car corner balanced.
I've also found that grippier tires need a few pounds extra pressure. Stiffens them up a bit to move the wear to the center of the tire vs. the outside edge. For reference: street tires (around 200 UTOG) 32 cold - 40 hot R-comp (100 or less UTOG) 34 cold - 42 hot 205/50/15 track tires Alan
I run 205/50ZR16 BFGoodrich g-Force T/A KDW 2 For the track I like them to be 40 psi HOT. That's about 32 cold. I run then at 36 for long highway drives.
Little tip I've found helpful - I put a little more pressure (pound or two) in the rear to help combat understeer. It might not work for you, or be to your liking, but I like it. On street tires, that means I get the rears up to 41-42 and the fronts around 38-40. This means that the fronts have to start much lower because they get most of the heat, so somewhere around 30ish. I have +- -3 front and +- - 1.3 rear. It performs balanced slides nicely when I go in too hot and is fun and neutral when I hit it right. When I put a left rear tire on the grass, it spins quicker than Bill O'Reilly hahaha :crazy: - Marc
THANKS everybody - good stuff.... I found 40 hot to be a good sweet spot for the Neo Gens also today. Definitely had to do some plus and minus adjustments to get there over the first few sessions - then the tires were pretty predictable throughout the day. But, that said, I need WAY better tires for the track...
Yep - I found this, too, into the "intermediate" grouping and beyond. As much as I loved sliding around on my Azenis (it's definitely fun), in order to continue to improve/get the most out of the car, real rubber is necessary. Looks like your suspension setup is here to stay, so blow through those tires and get some r-comps! There's a helpful thread here on which tires/sizes work well... - Marc
Or you could try the RE-11 or XS, as the next step up before going to R compound or full race tires. Thanks for the sweet spot of 40, that will help if I do some lapping with my Neogens which are going on the Challenge Wheels. Where did you start the day for cold temps? My track setup is 205/50/16 GY F1 GS-D3. (the last of the made in Germany).
dunno how useful this is as i am in a R50 but with my 205/50/16 F1 GS-D3 (also the last germany batch) i used tire wear indication to settle on 41f/40r hot ^that got the wear over the entire tread but i have no camber plates or adjustable rear arms (all i have are h-sport springs) i think it was ~36f/37r cold <-- again with an r50 my tires will heat up differently with a lighter car and different alignment (hot pressures are the important ones)
I started at about 35psi *warm* after the drive to the track. From there, I think I had to bleed off a few PSI on the left and add a couple of PSI on the right after the first couple of sessions to stabilize at 40 hot. Yeah... I gotta pay for some of my *current* mods... :lol: Then next on the list are light wheels and stickier tires (but not R-comps yet). And brakes... I roasted my front brakes (Carbotech XP10, stock calipers, Ate slotted rotors) on the last session yesterday - they were FANTASTIC before then. Still have plenty of pad left, I either warped or deposited on my rotors so I have nasty pulsing stops now, and I roasted my Super Blue so pedal is spongy. I converted the orange paint on the XP10s to ASH. Will tear it down tonight and figure out what's what... may just need to sand the deposits off the rotors and be OK... The BDM kit is looking better and better... and I checked the template on my street wheels and it fits... :cornut:
I have traveled heavily down the kill the brake pad road. My best advice is to just suck it up and buy the BDM. You will save yourself money in the long run. Pads are cheaper (only $75 for race pads), you won't boil fluid, overhead pads and ruin rotors. I just recently got the BDM and can honestly say that it ROCKS! Before buying the BDM, I went through a bunch of different pads, XP10's, HP+'s etc... Each time I went to the track I would overhead the pads and they would be crumbling by the end of the weekend. I think the key to the BDM is the 1.25" rotor, if the rotors successfully dissipate heat then the pads can cool and you wont end up boiling your fluid. The nicest thing, other than the fact the brakes stop like crazy, was having the exact same pedal feel when I apply the brakes. No more wondering how much the brakes are going to fade when heading into a corner.
Using the bullets? See Nathan's ShowCase :: R91 Bullet on GNAT I borrowed a set at MOTD and they fit, barely.
Nathan... that is REALLY GOOD news.... because the setup you tested is exactly what I think I'll end up with... and I own two sets of R91 bullets...
Paul, UK, lots of good useful information. Thanks for the updates. Of course you make me worry about my wimpy stock rotors after all the comments about your race pads getting toasted. I imagine you run in the advanced groups, I'm going to stay in the middle group. UK, how did you like the performance of your F1 GS-D3 on track. Did you wish you had a set of RE-11 or something a notch up? Don 07 MCSa, TSW Springs, other bits.