# 4WD handling without ESP/VDC...



## Ice512 (Oct 16, 2006)

Snow is commin..and ive a question that has been bothering me for a long time ever since i got my car.

My car has 4wd, but doesnt have ESP/VDC.

suppose my car went understeer when im turning into a corner, how does 4wd help this situation ??
The 4wd only kicks in when it detects wheel spin, not a skid.

So does 4wd help at all ? or its useless without ESP/VDC ?


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## flynn (Jun 23, 2006)

Don't get much white stuff here so you'll be more of an expert than me. I think 4x4 drive is probably better at getting you going and won't help so much if the urgent matter in hand is stopping. Mine came with ESP as standard but haven't had a chance to see how effective it is yet.


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## Rockford (Jan 28, 2005)

I posed a similar question last year.
I have VDC but still haven't been able to play around in a big open, snowy space to see just what it does. 
The t/c is great but like you, I'm wondering about under and oversteer situations. Will it pull you back from the brink? Maybe I'll find out _this_ winter. 

http://www.nissanforums.com/x-trail/114053-vdc.html?highlight=vdc

*Edit: Just re-read your post and I guess you don't really care about VDC since you don't have it. I missed that the first time.

If you're understeering, you're not likely to be on the gas (and have your front wheels spinning). Understeer scares the driver, oversteer scares the passenger. Your first reaction when in an understeering situation is to lift. When you do that in Auto you're never going to engage the rear wheels since the front aren't spinning (skidding yes, but spinning, no.). 
On the other hand, if you start understeering in Auto and* do* get on the gas hard (in an attempt to spin the fronts) maybe it would help. I doubt it, though. While that would probably get the rear wheels driving, you'd be adding speed to a vehicle that still has no traction in the front end. That's the last thing you need. Maybe with some left foot braking rally driving skills and a manual transmission you could make it work, who knows? 
I can tell you this: 4WD dos not mean 4WStop. If you're understeering, you've already lost traction. 4WD (and good tires) may allow to go quicker through a corner before you actually lose traction, but once it's lost a skid's a skid. 4WD may however, allow to regain traction sooner in mid-skid.
Of course, that assumes you're in full-time 4WD which you likely would not be (Auto).
So what am I saying? I'm not sure, but right after a big snow head out to the Yorkdale parking lot and play around. That's probably the only way you'll know for sure. I think it's important to find the limits of your vehicle and how it behaves once you've exceeded them. At least you'll be a little bit better prepared to deal with "issues" should they arise on the road.
Skid School's never a bad idea, either.


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## GFB (Oct 16, 2006)

Ice, I don’t know for sure but would reason as following: 

My XT brochure says AUTO mode acts both proactive and reactive. One example of proactive already mentioned in this forum is launching in 4 wheel drive. But, I am trying to say one gets the impression there might be more than one type of road condition calling for proactive steps to be taken by the 4WD system.

But, say no proactive steps was taken…, then the very moment you start skidding, the friction coefficient below the front tyres changes to some lower value and for that moment giving rise to some front wheel spin, in turn sending drive to the rear. As I understand, understeer is typical of front wheel drive, and oversteer of rear wheel drive – so, I guess sending torque to the rear would better any existing understeer situation. Even though we initially only have skidding, the static coefficient of friction changes to some lower dynamic value. Bottom line; you might regain some traction & control as Rockford also said.

Challenging question you asked – above is my speculation! However, I would hope that the proactive drive control would know you are on snow...


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## ERBell (Aug 7, 2005)

The car handles fine in the snow as long as you drive slow and use your common sence. 

I drive in Lower mainland Vancouver and in the valley out here in BC. The past couple of weeks are the first times I have had to use my 4wd and all was fine. 

I kicked the back end out a couple of times just to see and found the X Trail to be very stable.


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## Ice512 (Oct 16, 2006)

i found sthg that MAY surprise some of you guys...

I was reading the Murano brochure and found out tat Murano has the same AWD system as the X-Trail, and here are the exact wordings quoted from the Brochure.

Available All-wheel drive. A full-tiem system that sense if a wheel is slipping and immediately responds by switching from front -wheel drive to AWD.

Surprised ? So i'm guessing this system detects slips too ??


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## ERBell (Aug 7, 2005)

It is base on the 4wd system used in the Nissan GTR Skyline. The skyline's system also engages when wheel slippage is detected.


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## Ice512 (Oct 16, 2006)

but as Rockford has explained, the last thing i need is more power from the back when im understeering..lol
so in a way, this 4wd system will be doing me more bad when im in trouble ? hahahaha !!


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## Avery Slickride (Jan 6, 2005)

One thing to remember is that these traction control and electronic stability programs started as a way to approximate the benefits of AWD in 2WD cars. Installed in AWD cars, presumably they help. How much, I'm not sure. What I do know is that I've driven an AWD X-Trail through two winters in a snowy and (very) icy area. It doesn't have ESP or TC, but it hasn't given me an anxious moment. For one thing, the AWD system always launches with all four wheels engaged. For another, it's electronic, so it responds faster than the cruder viscous-coupled setups in some other small SUVs, which require a distressing amount of wheelspin up front before the rear wheels get involved. The best safety feature on ice and snow is your own common sense. If you keep that engaged, you should stay out of trouble. And good snow-and-ice radials are probably more effective than the best ESP system.


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