First autoX and need some advice
 

Hey guys,
Finally had my first scca autoX with my Z this weekend. Had a blast and can't wait for the next. I have a base z with sport pack, other than that my Z is completely stock and ran on stock tires also. A noticed a bit of understeer on the stock tires. Now i'm debatign what I should turn to for my first mods.

What would you guys suggest for these things:

1) Set of track rims and slicks (budget minded so whats the best bang for your buck)? Maybe a set of rims that I could also double up as winter rims?
2) A set of track anti sways? Typically do you track guys run front and rears? I guess this might be very tire type and setup dependent, or is the car always biased towards one side?
3) Brakes seemed fine, but I see numerous posts about upgrading pads asap if you start autoX or tracking.
4) Oil cooler suggestions. Even with my short 40 second runs, I got the oil up to 250. I know Zs have an issue with this, but isn't this a bit ridiculous. Even when i'm cruising on the highway @65 on a 90 degree day, oil temp sits at 220, this is normal?

Hope to hear your opinions and suggestions. Thanks

-Matt

Hi Matt--

My thoughts are as follows:

1) Go with some light 18's in 9.5/10.5 fitments for you track setup. RPF1's are a good choice. Tire is dependent on your total usage.

2) Stillen and Eibach are both good sways. Hotchkis are good but more aggressive (and dial in more understeer)

3) More aggressive pads might help with feel, but autoX isn't usually terribly demanding on brakes

4) 250 is not a problem. Autocross runs are short enough that you can comfortably get away with no oil cooler.

Couple of things.

First you need to determine class you plan to run. Stock class doesn't allow much in way of mods other than tires and front sway bar.

There are some things you can do with your setup now that will help eliminate understeer as well. Do you know what your alignment specs are currently? Put a little toe out in front, put some negative camber into the car as well.. What tires do you have and what pressures did you run?

On oil cooler. Unfortunately oil cooler bumps you out of stock class but at local level I don't think anyone will protest you if you run stock class. Oil cooler bumps you to BSP. A good oil cooler will keep you around 220 at ax events and 180 to 210 on street usually.

Brakes. Just put a good pad on the car. You don't need muchnin the way of brakes in AX. Replace brake fluid with high quality race fluid like Motul.

If you want to go beyond stock or just run for fun I would put good set of shocks and springs on the car. Good swaybars and upgrade to a top notch street tire like Bridgestone re11, Yokohama Advan a008, etc.

Definitely plan to run c stock and stay there, no intentions of making mods that get me out of that class (is there a good place to check what exactly is allowed). Being able to tweak the balance some would be great so i'll go with an antisway definitely. Also I would prefer to invest in a track slick so i don't put such a beating on my DD tire, and being more competitive while staying within the stock class of course would be great too with this mod.

I had the bridgestone re050a on there with 45psi all around. Didn't know what tire pressure to put these things too and how they would behave with a lower/higher pressure so i kept them put. Not familiar with street tires and their behaviours, only have dealt with slicks for race purposes before. The guy in charge said to keep your tire pressures up, and being new to this whole street car racing thing I listened (only have experience with light open wheel cars). Any insite on what to set stock tires would be appreciated bc i'll probably run on them once or twice more before i pick up a set of slicks.

I don't know what the alignment settings are at at the moment. Whatever came from the factory, if thats a reliable measure and tells you something.

I guess I'll stay away from the oil cooler, just to make sure I don't have trouble, and if you guys are saying 250 aint bad then I'm fine with that.

I'm very familiar with tuning suspensions, need to take a closer look under my z to see what I can tweak and adjust because I haven't been under it yet. But I wasn't aware that you would be able to tweak camber on a stock car, even if it is built to be a sports car.

Questions:
1) What would be a max oil temp I should look for and make sure I stay within?
2) Is there a particular track slick you guys are fond of? I doubt tire data on any slicks for our car is available correct? I definitely plan on having this tire just for autocross and the track, so thats all I need it to do.
3) Has anyone publicly released accurate dimensions of the 370z suspension geometry? Would love to put this into my kinematics software and see its camber profiles, ICs, RCs, etc.

Thanks for all the info guys, greatly appreciated!

-Matt

nevermind about the camber being able to be tweaked on the stock suspension.

You can only legally run a front sway bar which will unfortunately only increase understeer unless you are running DOT slicks. You are also limited in wheels to stock sizes and offsets which means basically another set of sport wheels unless another manufacturer makes a set with near perfect offset.

1) You wont have any issues provided you stay < 280F. Before I got my oil cooler and moved to SP I had a fast rerun on a long course and hit limp mode towards the 2nd half of the run. In standard conditions on a < 60s course I would never expect you to get above 260F.

2) A6 is the fastest auto-x tire hands down, but they wear fast. 50 runs and your done, and after several heat cycles they start to slow down. If you want to use it as a track tire as well then you can consider an R6 or V710 - takes longer to get up to temp but very nice manners on track. They won't last more than a 4-6 days on a busy race track though, depending on how hard you drive. R6's wear a little better. For track practice and HPDE I use Nitto NT-01's, and then use the V710's for time trial and auto-x.

3) Not as far as I know.

thanks a lot chris Slicks... yeh I was just thinking about the fact that you can only put a front sway on and how thats only going to make things worse for non-transient situations, so my solution was going to be to just put some more tire on in the front and maybe bump the offset out a bit to counter it and still be able to get some sway in there to stiffen things up (the stock suspension could definitely use it just from the few runs I did thus far). Didn't know exactly how that combination plays out and just signed on to post the question... Its a good thing that you brought up that you're not allowed to play with offsets or wheel sizes in order to stay in the stock class because that answers all those options.

Are you saying the A6, R6, or V710s (i assume they are all DOT slicks) in stock sizes (to keep you in C stock) don't have as much inherent understeer on the overall balance of the car with stock bars? Depending on what the behaviour of the car is on these slicks I feel determines what front bar I want to get. But I think anything more than the stillen bar which is like 20-40% increase or something like that (with 3 adjustments) and I'll probably be sacrificing way too much grip at the front for the gains i'll be getting in other places.

Thanks a lot on the tire info, very informative!

Matt

There's only so much you can do.

#1 A6s
#2 Front sway bar
#3 Cat back
#4 Shocks

Good luck

I thought the z was b stock?

Almighty Nismo yes, not regular one

Damn, theyve been classing me as b stock. No wonder it's been tough to compete with 225's....

It was B-stock originally, they reshuffled the classing.

Hey chris or anyone else with slick/track experience with a6s, r6s, or v710.

Just want to get this straight. So a6s quickest but softest tire compound out there. Maybe even too soft for track, so renders it strictly an autocross tire, unless u plan on blowing through tires. V710s and r6 pretty similar to eachother, with R6s having slightly better wear. Best performance street tire, nt01s.

@ chris: do u run V710s due to value? They seem like they are cheaper than the hoosiers.

Thanks, and sorry for all the questions!

Yes A6 should only be used for autox only, you will kill them in no time at the track.

I had V710s on my 350. I love the tires, but I found my time to drop considerably after four events. By the 5th or 6th event, I was running roughly the same time as my RA1s. It's a great tire, you just have to prepare for the treadlife. I do have to say that I did run very low pressure with the V710s, probably killed them quicker that I should have. Also my friend's 350 with modified suspension seems to be much easier on them than mine (we both drive roughly the same way)

Yeah the V710's will wear and heat cycle out if you use them for every session. I've taken to using them only for time trials and the practice session before the time trial to set pressures and get a feel for the grip. For the rest of the sessions I use the NT-01's. They sit in-between a premium street tire and a slick in terms of grip and times. So yes, it is an economical decision, I like to do a lot of track days and can't afford $5K a year for tires. I think the V710's a slight grip advantage over the R6 which is why I like them for TT's. I also flip my slicks halfway through their life expectancy to get a little more out of them.

I have a friend with a Miata that runs A6's for the TT but basically even in that light car it is a one lap deal. Each lap time after the first gets slower where as with the V710 and the R6 each lap after the first gets faster as the temperature builds.

Be aware that if you auto-x club runs a street tire PAX then the NT-01 will not qualify as it is 100TW tire and the cut off is typically 140TW.

If I recall correctly, the size the V710s come in for the 370 is crazy expensive compare to all the other size too. I really did like my V710s, but I couldn't believe how my times dropped after 4 events.

In all seriousness, you might want to try a couple more times before you drop money into something that you have only tried once. You know how many people quit after the first four or five events. Waking up early on Sunday for 5 runs is not everyone's cup of tea, also track day is the next step for a lot of people too. Out of the 20 novices I see every year at each event, I would say only 2-3 stay on to be full timers.

They don't make the Kuhmos in the correct sizes for the 370 so you're stuck with A6's if you want an autox rcomp.

Thank you all so much for all the information. Will be very helpful in making my decision. I plan on getting a slick in another two events or so. I'm definitly going to stick with autocross and only get more deeply involved in track days/weekends as my expendable income increases for sure :) I've designed, built, and raced 5 open wheel fsae cars in the past. And not just being a member on the team but being the head design engineer for 4 of those years, so I can say racing is definitly a huge part of me, hence also purchasing my z for this purpose :) so chances are pretty slim I would quit after a few events :)

Once again, this forum is immensely helpful and I appreciate all the feedback from everyone! Picked up the stillen front anti last night. I think its conservativeness vs a hotch was the right thing to do if I'm planning on staying C stock and not planning on modding more suspension than that for a while.

Hope to run with you at the Tri-State then (minus the R comps)

If you stay in C Stock you dont have much you can do.

As mentioned front Swaybar, Shocks, cat back exhaust system and tires are only real changes. You will be camber limited in C Stock. You cant change stock offsets more than .25. These cars turn well so I wouldnt rule out front bar. In stockish base car you will want roll stiffness espeically if you are camber challenged.

A6 is only choice for AX if you are serious. I will say I ran A6 on track and they were much tougher than I had suspected. I ran two full track days and put 60 autocross runs on my fiorst set of A6's and they still have tread! I'm no wall flower either. I have spun car numerous times in AX, spun tires out of turns etc. My lap times were similar on both A6 and R6. A6 would get a little greasy towards end of hot session in 80 degree wheather.

Next step down would be Kuhmo 710 or Hankook 214. You not going to get ideal size in these tires however. Avoid the BFG r1 if AX is your gig as they need heat to work. anything under these will not be competitive in C Stock.

Nittos, Toyos, etc treaded DOT R's just dont cut it in AX as they require higher operating temps and just dont stick as well as slick DOT tires.

Street tirees. You might have a local street tire class you can run. If that is the case and they allow 140 Treadwear. Bridgestone re11, Yokohama Advan a008, Hankook RS3 are some of the top tires. I run cheap $200 a tire Nitto NTO5's and they are fine for street tire. I run 285 rear and 275 front. I use 43 front and 40 rear for those street tires. But I hate street tires in AX. I dont like abusing my street tires.

Back to A6. You can run 295 hooiser A6 up front on stock 9.5 and I think most of the C Stock guys run 295 on 10.5 back too. Because I run BSP and have a lot more freedom with suspension I run 315 rear and 295 front and car turns like there is no tomrrow.

Im rather biased but I cant stand running the 370Z stock in AX. Even my Nismo was frustrating. The car lacks proper LSD and suspension tuning to truly do well against much more agile MX5s in that class. Without a proper LSD you are definitely going to want a bigger front bar or you will be laying down big black stripes on inside wheel all the time if you are an agressive/fast AX driver. Did I say stock VLSD sucks? Man does it ever suck! I think thats the one thing that keeps the 370Z from doing well in Stock classes. Sure there is one hot shoe who podiumed at nationals but I'd put money on him being faster in a national class MX5. Also beware that AX seems to accelerate VLSD degradation in performance. Mine after a few AX days really seemed to fall off.

It took a lot of work just to tune out all the crappy dynamics of stock Nismo for my car to finally feel good in AX. I cant imagine driving a sloppy base 370Z in AX would be much fun if you are used to open wheel cars. They are very sloppy cars in stock form. Guess with a real good damper you could tune the car to work a little better.

Good luck! Keep us updated to your progress!

i dont have any problems autoxing my car stock, but i run in a street tire pax class so i have different standards than the a6 guys. the modded cars and slicks are nice, but street tires can be challenging in their own rights on a front heavy car like the z.

I haven't podiumed...yet. Last year was the first season I've ever run on R-comps and the first event we did with the shocks. Both the car and driver are much better sorted now and anything less than a podium finish would be a big disappointment for this season.

Also to emphasize what Shamu said, get 295's square for your Hoosiers, even with the 9"/10" sport wheels. Also I would recommend reconsidering the stillen bar and going up to the hotchkis because of the traction issues he talked about.

Street tire -> Stillen
R-comp -> Hotchkis

The Hotchkis is too much for a street tire IMO, especially in a front only application. I ran 6 months that way and hated it.

Awesome detailed information and very helpful from all of you, especially from you shamu.

Its funny how u bring up how sloppy the z is in stock form shamu. Its the first stock car I've ever done any track or autocross with so I was prepared and expected things to not even be close to the same level or similar at all. I don't know how it compares to others, maybe the z is especially sloppy in stock form (anyone with experience with autoXing other stock cars chime in please!). I just had this discussion a few days ago with my buddy when he asked me how it compares. Its completely different, and I wasn't expecting it to compare or be at that level so I wouldn't go as far as saying its no fun, it definitly is, but the responsiveness/transient behaviour, balance, acceleration, braking... everything is just way off from an formula sae car but I think its inherent to expect it to be. Also not having 4 way dampers, front and rear adjustable bars, spring rates, camber shims, ackerman brackets, etc to tune with on the fly between runs is a huge downside definitely. Saying it that way makes me rethink what I'm doing trying to keep the car in stock form when I could probably have a lot more fun with it if I was able to step out of stock. Haha, its just I don't even want to see how much a set of good dampers, a few spring rates, adjustable suspension linkages, front/rear bars, diff, etc start to cost for this car.

But I think an adjustable 2way damper is inevitable and will be a very near upgrade (outside of my front bar), but I'm going to give it at least one track day and a couple of autox before the investment.

As for the bar discussion. Can the car in stock form just on rcomps get benefits from using just a front hotchkis? I feel with a stock loose rear end and the already prevelant understeer it would be difficult for front end grip having just a front bar that stiff. Does switching to rcomps really play that nice with this setup? Maybe they are less load sensitive than I thought they would be and that's why :/ That would be very suprising to me, especially cause the z isn't that light. I just figured even on rcomps with a stock car the stillen would have enough stiffness in it to balance that fine line of stiffening up just one end of the car enough before u start having diminishing returns and losing time. Has anyone on here ran front hotchkis and rcomps with an otherwise stock stepup at the track or autox? Or are u front hotchkis guys also running other mods(like a rear bar, different spring rates, dampers, etc)?

Thanks a bunch and I enjoy the conversation greatly. This is all great information for someone just getting started with autox and track days in a z. At least for me it is.

my last six autox car were stock rx8, new prius, stock c6 corvette, stock 350z, miata, 996 911. they all lean up to a certain point. its not fun to drive a car that leans a lot, but you can get used to it if you try. i change cars every 24 to 30 months, so i refuse to modify anything as it gets too expensive. unless you have a big budget, any bsp build will cost you at least 7k. its worth it to some people.

oh btw the 370 is not sloppy compare to my older cars. i would say the miata/rx8 were the easiest to drive (it actually leans more), the 370 is definitely 2nd or 3rd. its better than the corvette and 350. i give it a slight edge over the sti

got a chance to put my stillen swaybar in this weekend. What a difference it makes to the overall roll of the car (middle setting at the moment). I was definitely not expecting such a drastic difference, considering everyone saying its a mild bar. Definitely a much more responsive car in transient conditions. Haven't had a chance to push hard enough to see how much worse it made the understeer, but I can definitely see benefits in the overall response and driveability. Really happy with the upgrade and I definitely can see gains in the next autocross coming from this. Hopefully I can get some time next weekend to play with the adjustments and see how much of a difference I feel between the adjustable settings.