OK total track newbie here but huge racing fan and have spent countless hours in Gran Turismo (stop laughing). So I understand the basics, slow in-fast out, steer into slide, yadda, yadda, yadda - but have never really driven my car hard because its stupid on the street. Heck at HPDE events "hard" is only 7/10s but with ZERO experience even that level was pretty intense. 100 MPH isn't fast until you have to brake for a turn

Anyway I fully expected my bone stock '03 Touring Z to be a little tail happy on the track, after all it doesn't take much effort to kick the rear end out on the street at low speeds. Turn in, apply heavy throttle too quickly = SLIP light and VDC cuts the power rear end swings back in line... no harm, all good fun

However on the track my experience was very different from the expected condition. The car pushes like a FWD brick. The car I thought was balanced, light and fun became a heavy slug. Now I know the Z ain't light and with the VDC on (yeah I'm chicken sh... so what) I found the car was difficult to rotate

For reference track was Homestead in Miami, temps were mid 70s

So what's the problem?

1) Crap tires? - Running Bridgestone Pole Positions, RE970s (I think) nothing special.
2) Brakes? - Stock replacements, even the standard fluid (big mistake there, fade from hell)
3) VDC nanny just doing her job - turn off to enjoy car
4) Nut behind wheel? - Silly noob, too slow + early apex = fail
5) Stock power too low? - Needs more cowbell?
6) Not enough steering effort?
7) Nothing wrong, Zs naturally understeer (several professional reviews mention this)
8) Other??? Suspension?

Even my instructor was a bit miffed about the amount of understeer/push - at times the car would just plow forward while I attempted to turn. He figured the tires were junk. His track ride is a slightly modded Z06 Corvette.

Suggestions? Comments? Thanks

 

I haven't tracked with my 350z yet (bought it a few weeks ago), but I have tracked with other RWD cars I own, so take this with a grain of salt. My guess is that leaving VDC on was your first mistake. Try turning that off. The car should be much easier to rotate after that.

As you gain some more experience, you can look into the DIY to fully disable VDC. That should enable the car to respond better to more advanced techniques like trail-braking.

 

You should change the tires. I used to run the RE970 when I first purchased my Z, they came on the car. They are rock hard and overheat quickly. you should also consider going pretty wide when you do change to a better tier. I run 265s square and plan on going a little wider next time around.

I think one of the easiest ways to dial in under-steer/over-steer is with adjustable sway bars. The adjustable sway bars could allow you tune where/when you want the car to break lose.

Hope this helps

 

Honestly I think it is combination of all of the above but mostly "the nut behind the wheel". One thing that it definitely is NOT is "the lack of power".

I also think you should go and re-read what "handling oversteer" is. What you are describing in your post above is power induced oversteer if that is the fun you want you need to look into drifting as that is not the fastest way around the track.

You should invest into more seat time with different instructors before you go changing anything on the car. Some instructors even though they might be great drivers are just shitty instructors

Try to go along for a ride with some of them or ask them to drive your car to see the line you should be taking or give you some feedback if something is not OK with the car. It might be as simple as bad alignment or tire pressures...

 

Congrats on getting to know your Z better. Is your car stock?
Here are a few things I notice in stock form that creates the understeering issue.
Staggered narrow tires, toe in, too little negative camber (especially when there is more in the back...).
At least these are what I am trying to fix for now. Let's have the more experienced members chime in.

 

#7 is it. For track these cars really need a square tire combo. I laugh at the street kids who say their car is neutral after suspension mods yet have never been on a track with it, completely different world. Then the camber part has also been mentioned, the lack of front camber is directly related to the lack of front grip.

 

Thanks for confirming. Clearly more seat time is needed. I'm not making any modifications until I learn ALOT more. Honestly since the car is my daily driver I'm not into huge mods anyway. Just like the idea of driving on the track away from soccer moms in SUVs updating their FaceBook status

Would making some tire pressure adjustments help me with the learning curve / feel of the car?

 

You're gonna need a stickier tire. An RE970 is a nice all-season tire but has no buisness on a track. Switch over to some RE-11's or something that will hold up under abuse and actually provide grip.

Address your brakes, although you know that now. Brakes/tires are the most important parts of the car as they let you control/stop/turn the car. After that, just practice and practice some more until you are getting most of what the car can offer out of it.

 

I am going to disagree with this.

A better tire is great for lap times and competition, but they really do nothing to help learn vehicle dynamics. Actually, the more the tire slips the better you understand what the chassis is doing. Too many times people aren't happy with the way their lap times stack up to what they have read or others at the event (what, A Miata passed ME??!!) and go out and buy R compounds or the like. This just covers up driving mistakes, and that “advantage” will disappear once everyone else is one the same compounds as well.

Yes, the 350Z is set up to under steer with OEM tires sizes and the VDC. Pretty much every new car is for safety reasons. Human nature allows us to deal better with a car that refuses to turn and goes straight, than one that is spinning out from underneath us. This doesn’t mean it’s a bad track car, and even the OEM setup can teach us a lot. If someone tried to “fix” the inherit safety measure built in without developing the skills to manage it they usually go to the other extreme. How many times have we heard “I went to a square setup and not the car is trying to kill me” or something similar. We have also see too many spend thousands on “set-ups” only to completely redo them once they have more seat time.

Listening to the symptoms I think the car is doing exactly what is design to do, and I also see a bit of driver learnings going on as well. I bet one big reason for all the under steer is heavy throttle application. You come into the corner at a lower speed, then apply the throttle heavy with smooth steering input (all of this is a good thing!). There is also the factor of pedal moderation and transitions that can cause significant chassis weight shift, transactional forces, and sharp power applications. What is then happening is with the larger tires on the back you are getting a good amount of traction and acceleration, thus taking a significant amount of the weight off the front. I can almost bet as you get high entry speeds you will have less and less push because your throttle inputs won’t be as sudden and as much. You will still experience push, but you will also see some rotation mid-apex or before. As your experience increases you can also start incorporating trail braking as well. Once you are comfortable with high speed rotations, then you can look at changing the car itself. Tune it to your liking. At this point it’s almost all about the diver, not the car. After a while, you will know what you like in the feel of the car, and what traits you want to enhance or eliminate by changes.

 

I was actually thinking this as I typed but I had to run and didn't want to go back and make a big speech out of it lol. You are absolutely right, it's far better to learn on a not-so-sticky tire, so you can understand better what you do and how it affects the car and traction, contact patches, all that good stuff. Learning on a slippery tire will force the driver to feel and improve, not rely on having grip. It will make you drive slower, which as you said, slow is smooth and smooth is fast.

 

Exactly how my car behaved when my it was fully stock and it was my first time on track.

Now that you know the car's limit, you should be able to drive smoother and smoother as you progress so that the car won't understeer too much.

 

Awesome info guys THANKS.

I've heard that most cars, even "sporty" RWD ones actually understeer naturally as a safety measure, but it was just such a shock to me on my first day of hard track driving. I assumed the back end would at least squirm or step out with my ham fists at the wheel, but the darn thing just plowed.

Trust me I'm not making any mods (other then BRAKES) until I feel I've gotten everything out of the stock setup. I don't need to be "fast" to have fun and that what this is all about. Some of my friends just don't understand it - I only hit 100 mph on the track and they laughed, but then I explained its all about the CORNERS. Any fool can do over 130+ going straight if given the space, you just keep pressing the GO pedal. I want to learn how to DRIVE which requires brakes and turning

And now I fully understand Miata guys... those little things look like a blast out there, they eat up the twisty bits

 

Listen to Marty^.

I'd say don't worry about the car and just slow it down, do what your instructor tells you and you'll be fine. They will get you faster as the day unfolds. You need to learn the car yourself, how its limits affect your driving style and adjust as needed. Slower with more control = faster.

 

The only thing I would change on you plan, add front camber arms. They will take some understeer out and give you a lot better tire life. Tire life is the main concern.

 

Having been an instructor with Speedventures for years, this is the number 1 issue. The problem is normally a student who comes into a cornet too fast, with the brakes on fire, and then trows in a bunch of steering lock. Front tires just give up.

I suggest you focus on yourself and you're driving before making ANY mods to your car.

 

All of the above. But I thought I'd add that my VDC button was dangling out of its receptacle and my knee hit it once to turn it on by accident mid lap.
I went right off the track wide in the easiest slowest corner on the track.
Get back to learning, but learn with the VDC off and go a a pace you are comfortable with.

 

I did some reading but still don't fully understand what the VDC is doing. Its clearly more then just traction control due to the yaw sensor. So is it also making adjustments via the ABS on the fronts? Or is it really only killing the throttle to keep the traction on the rears? I swear the SLIP light never came on during my track session but I could be wrong as I was focusing on the line ahead of me and not any lights on the dash.

I figuring leaving the VDC was safer (for now) and my instructor agreed.

 

If you are running the proper tires ( difference in height front to rear) you can run fast laps with VDC on. I can get within 1.5 seconds with VDC on when I was running a staggered height setup.

ABS and VDC engaging as you learn to drive just tells you that you're screwing up.

 

+1 to car naturally understeers. But the driver can make it worse.

I put a square setup and the understeer almost went away. It still feels like it understeers, but much much less.

 

My 2 cents…

Answer this question. Did your Z understeer on your way home from the track?

I suspect your answer will be “no”. How is that possible if you drove home on the very same tires, brakes, alignment, etc. that worked so poorly on the track?

Then what is going on? What variable has changed?

Although you won’t realize it until you complete a couple more track days, that’s your answer.