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.