Zmazing03

iTrader: (9)

Watch out for snap oversteer. Its a doozy.

Kolia

iTrader: (2)

You porbably just missed the SLIP light. Altought the car will let the rear end stand out a tiny bit as long as you're not counter steering (on VDC equipped cars. TCS doesn't care about the steering).

If you really want to loose the rear, make sure you turn the TCS/VDC off.

Snow Z... Nokian make the RSi tire in 255/40R17... It's soo tempting to get those mounted on the track wheels... But it wouldn't be reasonable to deprive the Titan of it's winter tires this year...

tienlo

Keep steering until you hear the B in BANG

350zz053

iTrader: (8)

This a trick question!!! lol! What came first, the chicken? or the egg?

rockinbboy

iTrader: (1)

Why shouldn't you counter steer on VDC equiped cars? I tried also with the TCS OFF and I definetly lost the back end a lot harder/faster than with it ON. That was too damn hard to control too.

Kolia

iTrader: (2)

I meant that the VDC will let the car oversteer a tiny bit (it's not really oversteering, more like a 4 wheel drift) as long as you're pointing the steering in the direction of the rotation. As soon as you counter steer to catch a spin, the VDC will kick in as it sense the car turning one way while the driver tries to turn the other way.

My comment wasn't meant to be understood like VDC equiped cars don't need counter steering.

SteveZ

iTrader: (3)

When you make that transition from sliding to countersteer the VDC will kick in and usually snap the rear end right back into line. What you describe points out one important aspect of VDC - lateral loss of traction in the absence of a transition, it won't do anything much. It's when you have significantly different things going on across the 4 corners (just like as in the transition you describe). VDC in a 4 wheel drift won't do much at all until it detects a significant differnce at one of the four corners in linear traction - not lateral. That's why it kicks in during the transition you describe - one of the 4 corners (rear in that case) has a change in linear traction and wheel speed relative to the other one. It doesn't otherwise do squat for loss of lateral traction if it is relatively the same across 4 wheels - when you 4 wheel drift it only kicks in when you come out of it, transition cross over to L/R or R/L - because wheel speed changes relative to its other side. And yes, countersteer there definitely applies.

Word of advice if you drive in ice and snow - which is a very interesting place to go if you have the tires and snow time, you learn a lot about the traction aids in our cars. With my 350's open diff (Base) and no VDC, I had to worry about parking one wheel off the dry pavement - game over, it just spins and the one on the road did nothing. VDC is a little different -
1- Ice and Hardpack, VDC is your very best friend...it works great. Turning it off on normal clean pavement maybe isn't such a good idea when you understand the next part - it keeps rapid transitions from becoming something you may not expect or be able to handle. I once drove in an unexpected snowfall with freezing rain on the Pilot Sports, VDC is the ONLY reason I was able to get anywhere, otherwise the car would have just slid off the road on a sudden L-R or R-L transition. TCS would not have been relevant. Never try to drive in a half inch w/o dedicated snows - just park.

2- deeper snow like 2-6+", turn the damn VDC off - if you are starting out it detects alternate side wheel slippage and you cannot spin your way out of a few inches. The car will just cut power to the rears alternately until you don't go anywhere.

I took a side road by accident last Winter, tried to spin the rears to get the traction I needed, but the VDC killed forward momentum when it figured I was steering to the right, but the rear end was sliding to the left. I realized it was impeding my forward progress, turned it off, right away was able to back up, go forward w/o problem through 6" of fresh snow (that is a lot - much more than 6-8" and it packs up under the car, wait for the plows).

The VDC picks up the transitions that are common in snow where the rear end goes L-R-L etc. it can bring you to a very quick halt. In this case you want to spin to your hearts content and let the snows dig down through the fresh stuff to the hardpack.There's a lesson here that transfers rapidly to pavement w/o snow - pavement isn't so slippery, but the lateral vs. in-line loss of traction behavior is about the same, just takes more to lose it...VDC is your pal when something unexpected happens, not such a friend when you are pushing the limits of traction knowingly

SteveZ

iTrader: (3)

If you find it hard to control, leave it on all the time. Its main function is to keep unexpected or rapid transitions from becoming bad experiences. If you turn it off and something truly radical happens, you will likely have bad experience. You can still have a great time driving the car and never turn it off. If and when you do, you should by then have such a good feel for what's happening it won't be difficult.

The car is neutral and one of the better behaved I've ever driven out of the box. That said, it's not light, it has stiff suspension, gobs of torque across the power band, and while this is all good it is a bad thing if you begin to lose control of the car and don't instantly have a good feel for how not to. Observe what the traction aids do - one of the reasons for the VDC switch is that it does not work fantastically well in all situations - not so you can just turn it off to tear up the pavement on a summer day.

Kolia

iTrader: (2)

From reading your post Steve, it looks like you might be a little confused as to what is involved in the VDC operation. Here’s a short description from the Nissan Technical manual. You will find that the VDC system does know how many lateral G are involved in any movement, as well as the rate of rotation which is compared to the expected amount of turn from a giving steering angle.

It’s not just wheel speed that’s taken into account.


Edit: I've re-submitted the attached files for clearer ones.

SteveZ

iTrader: (3)

Nice docs - no, I am aware of the steering input and the yaw angle sensor, braking, steering, etc. My point was the most significant input is the sensation of a rapid transition as detected primary by the yaw sensor and the steering pressure/angle, the bottom line is the VDC really kicks in when it senses abrupt transitions.

You could plaster the wall with all the possible combinations, and note all of my comments assume you are completely off the brakes.

In deep snow the problem is if the yaw rate increases and the rear is sliding starting out, and you are steering the direction you wish to go (straight), the VDC will kick in and effectively stop you cold.

Not confused in the operation of the VDC, just trying to simplify, have 4 years in total driving all year round in CT, believe me, I damn well know the majority of variations of the VDC effects. The combination of the VDC, TCS, and ABS will stop you cold if you are trying to start the car on a hill, for example, in th snow.

My other point is because it kicks in when certain thresholds are passed, turning it off is not a good idea for people not comfortable with the car.

Kolia

iTrader: (2)

I didn’t mean to imply you were wrong in your analysis.

I’m just adding to your data that’s all. Although the VDC/TCS/ABS system is interconnected, they are still individuals units and I like to keep in mind which system is responsible for what. Mainly because some Z have TCS/ABS only while other have VDC on top of that and it might help people understand what their car is doing.

We often get topics about “I spun my Z with TCS ON!”. Something that is absolutely normal if you don’t have VDC…

The VDC will work on turning the car in the direction the steering wheel is pointing.
The TCS is the one that kills power when wheel spin occurs.

Asterix

Good information I found over on Supraforums:

Oversteer Part 1: Right-click, save as
Oversteer Part 2: Right-click, save as

Understeer Part 1: Right-click, save as
Understeer Part 2: Right-click, save as

The whole lot of videos are here.

The only part I have any disagreement with is the lifting of throttle part. The Z is way more forgiving for that than either the BMW or Porsche because the rear suspension in the Z controls toe much better (as does the Supra). It is still important to get the amount of power right; it's just less critical in the Z. Also, if you're on ice or snow, putting in the clutch is the best and fastest way to get the back end to behave if it starts to hang out.

Asterix

jungle

Lots of good answers on the mechanics of oversteer and the VDC, but ultimately the SHTF because the driver makes a mistake by going too fast for conditions.
Exceeding the limits of the car on a public road is just stupid. Drive within your limits and the car and accept that you are the one causing the SHTF situation. The onboard systems may not be able to cope with anything you throw at them, they just enforce a lower safe limit- you can too.

mavtais

iTrader: (12)

It's much more of a "feel" thing. Throttle, steering, speed, and even brakes all play a role in what your car does in a hairy situation. No one can tell you how to regain control. You just have to understand the physics of RWD and feel it out.

Drift_corners

TO be honest if you need to ask ?'s like that, then you should not even begin to drive fast enough to have it slide. Iv raced carts and bikes my whole life, and cars for the last 3 years, im still a younin. learning to know how to feel what your car is telling you is not easy, and if you dont know basic countersterring, then your not in a good place to start to learn, If you want to get better go to an autocross. there will be people there who can teach you first hand. In a safe place.

SteveZ

iTrader: (3)

No offense taken. People do throw the terms around like TCS and VDC are the same, etc. Really great info. They really do work together when both are present, where I find VDC's effect negative at times is in braking impact.

Somewhere recently I read an article on an Evo or similar, and it really struck me how much Japan values stability in a car (drifting aside) and the idea of how a high performance car should stick w/o sliding, eliminate oversteer, etc. A different mindset...

psucaptkickass

I am going to track my car in the winter

Location : NoVA in the winter.

SteveZ

iTrader: (3)

Now I see what you were referring to, I think. When I said VDC doesn't know lateral, that is not correct. What it picks up is Yaw, which to me is lateral movement of one end or the other of the car relative to the center. My observation is in relatively uniform 4 wheel drifts, VDC does not appear to kick in in the form of engine management, brakes, etc. unless there is a significant difference in the steering direction of travel and the 4 wheels. Also kicks in if there is a rotation around the center axis (over-simplified).

What I have never seen in print is the following situation:
1) Got into some deeper snow than expected (have Pirelli Snowsport 240 dedicated snows)
2) With VDC on, appears that as the rear spins the wheels and there is yaw to the driver's side, there is braking on the front - w/o my foot on the brake. The way I could tell is my limited forward progress showed the front wheel was not turning but pushing through snow, aggravating the impact of VDC because the front tire was meeting resistance.

I got out, very puzzled as have driven through much worse, and note the sliding of one or both front tires - not sideways but as if they were locking due to braking. Turned off the VDC, which to my understanding also cuts the TCS on the G Coupe at least, LSD is of course still working, instant forward progress. I was spinning both rears but the drivers' side a bit more which caused the yaw, slippage to the left. The difference was dramatic. I used the same approach anytime starting up in deeper snow and the tires would bite down, find traction, and I'd move. Turn on the VDC, and I felt like I was plowing the fronts even though pointed in the direction of travel.

My 350Z came with no TSC, no VDC, and an open diff (2003 Base, my understanding is today the Base comes with TCS). Life is much simpler in that case - you cannot back out of the driveway with frozen dew!

As I head into Winter #3, I know a little bit more than before, I refuse to park for the season. Even when I head out for overnight trips the threat of snow alone would cause me to forgo the Z or the G, then I'd see three days of dry pavement. The Pirellis make surprisingly capable studless tires and you definitely get a feel for throttle, brakes, and traction aids when there is a LOT less friction available

Again, thanks for the great info, happy driving. I am jealous of NoVa track above, nothing close here in Winter that isn't closed. Lime Rock is in the NW CT hills where I live, usually the area of heaviest and longest snow pack. No track for me in 200-300 miles

Swiffer

iTrader: (8)

The best practice that I had when first driving a RWD car (94 Camaro) was taking it into an empty parking lot (no cars, light posts, or curbs) and having fun. This was a good way to leard the dynamics of a RWD car. It can actually add a bit of fun to the winter months if you know what you are doing.

As for the rain, I just always drive a little more careful because you never know when things will start to slide or break traction. ALWAYS get your speed down before the turn, never wait until the last minute.

iyah

iTrader: (6)

counter steer!! DUH!