Any Reason Why I Can't Go 245/45 Rubber On The Fronts?

[Unique]

With VDC one press of the button is only semi off, with the light coming up on the dash. Having VDC totially shut down is different again. Hold the button down for a few secs and it is off off, the light on the dash will also go out. You cannot push the button to reactivate it. You need to turn the car off and on again for VDC to again be active.

Edited September 16, 2009 by Unique

[superspit]

With VDC one press of the button is only semi off, with the light coming up on the dash. Having VDC totially shut down is different again. Hold the button down for a few secs and it is off off, the light on the dash will also go out. You cannot push the button to reactivate it. You need to turn the car off and on again for VDC to again be active.

woah!...Can't wait to get home and try this out!!!..(I'm driving the Festiva today)..Hope it works!!!....Will let you know later in the day how I went. (into a tree...lol!)

[Touge Kyousou]

Yep, have had VDC kick in even though i had it off (semi off).

[V35_Paul]

Cool it works

had to hold it down for about 7-10 sec

Edited September 17, 2009 by V35_Paul

[FlyingEL]

Correct me if I'm wrong, I thought the VDC only control our drive wheel, not the front at all.

[rs73]

I believe the way it works is by electronic brake distribution (ebd) which means it can 'clamp' either sides of your front brakes in order to stabilise the car, as it sees fit... it works on all 4 wheels through the abs system

[mosoto]

Correct me if I'm wrong, I thought the VDC only control our drive wheel, not the front at all.

VDC has sensors on all 4 wheels

[scathing]

Correct me if I'm wrong, I thought the VDC only control our drive wheel, not the front at all.

VDC can control braking force on all four wheels, as well as overriding your throttle pedal and closing the butterfly (which is the TCS part).

[superspit]

VDC can control braking force on all four wheels, as well as overriding your throttle pedal and closing the butterfly (which is the TCS part).

This makes sense...It's this 'closing down' of the induction system that is the part that I'd like shut-down for my own personal safety reasons, as explained prior.

So VDC encompasses all the various safety 'sub-systems' in this car (EBD, ABS, TCS)? and is controlled by the one button labelled VDC?

If so, then the TCS would be the part I'd like turned off, and only TCS.....easier said than done?

I have no issue with the EBD/ABS systems....Infact, the EBD system is quite impressive on this car..... (under test conditions anyway).

Gettin' down to brass tacks here I feel.

Cheers.

[scathing]

So VDC encompasses all the various safety 'sub-systems' in this car (EBD, ABS, TCS)? and is controlled by the one button labelled VDC?

(Apologies in advance for the long post)

No, VDC is independent of the first 2 systems and only works while you're cornering. However, it does use the same hardware.

EBD controls brake bias front to rear, depending on the weight on the rear of the car.

ABS detects wheel lockup under brakes, and releases pressure to that caliper and reapplies it.

TCS detects wheelspin under power via the ABS sensors, and closes the throttle butterfly to cut power.

The system has 5 inputs that I'm aware of (individual wheel speed via the ABS sensors, yaw via an accelerometer in the middle of the car, steering angle, throttle position, brake position) and works in conjunction with the above safety systems. On the output side it has the ability to control your throttle butterfly, and the clamping force in each individual caliper.

For a given wheel speed and steering lock you should turn at a certain rate. If the value that it's calculated is different to what the yaw sensor is telling it, then it knows that you've deviated from your desired line. The difference in value will tell the car whether its turned too little (understeer) or too much (oversteer). The VDC also knows that, for a certain amount of steering angle, your inside wheels should also be turning a certain percentage slower than the outside wheels. If those relative speeds don't fall within its acceptable range, it knows you've got a bit of wheel slip.

The system is accurate down to a single wheel. If your 2 front wheels are rotating in the appropriate ratio and your outside rear wheel is spinning at the same speed as the front, but your inner rear wheel is not spinning at the correct speed or ratio, then it knows you've lost traction with the inside rear wheel.

The VDC will then cut power using its TCS component, and also adjust the force on the brakes to bring the car back onto the ideal line with all four wheels spinning as fast as they should be.

It doesn't matter if you're under throttle or under brakes, VDC will always be there to help you (TCS only works if you're on the power). Technically on your car the TCS is considered a part of the VDC so its not really independently switchable. ABS and EBD can never be switched off (it can only be "disabled" by causing a fault in the system).

-

As an example of how VDC works, lets say you were to get push understeer under throttle. If the push is gentle it might compensate by just grabbing the inside front brake, to pull the nose back into the corner. If the push is heavy, it'll cut power as well. If its very heavy, it might also grab the rear brakes to slow the car down.

If you were to oversteer it'd definitely cut power, and grab the rear brakes to slow them down (TCS only cuts power). Some sources I've read said it'll also grab the front brakes to stop you from fishtailing because you've suddenly slowed the rear wheels so much.

ABS also only triggers when you're close to locking up. If the VDC detects that your trail braking attempt has gotten you in trouble (you could understeer or oversteer), it'll release the pressure in the appropriate calipers to bring the car back on line. This might be well before the tyre has almost locked up, where the ABS wouldn't trigger.

The guys I've spoken to who've tracked their 350Zs with VDC on have noticed that it makes the car more understeery. They've also noticed that it reacts a little slowly, which has given it a HICAS-like reputation for annoyance among Z33 drivers. For example if they go around a corner and understeer, they'll come off the gas to tuck the nose back on line. The VDC, detecting the slip, will also do some braking and pull the nose too far in. They'll react by unwinding some lock, but the VDC will detect the nose coming too far and also let the nose drift. Which causes understeer again. Rinse and repeat.

If you just press the button, the information I picked up from Best Motoring's "350Z Shock" is that the VDC stay off unless you tap the brakes during a "moment". Tsuchiya noticed that he could inertial drift and powerslide the car all day long, but the moment he tried to initiate a slide with the brakes the VDC would kick in anyway, and straighten the car. I can't remember if the car was TCSing when he tried to throttle on after then, or if he had to wait for the car to straighten up and "be safe" before being able to to break traction with the throttle again.

[rs73]

interesting...

carmakers by default always tune a car's handling to induce understeer...

after all, despite being disliked by seasoned circuit racer and drifters, understeer does saves live...

your chance of survival is greater if you hit a tree head on with all those crumple zone in the bonnet to absorb the shock around you and you landed on that airbag deployed out of the steering wheel...

even with side airbag, ending up sideway with a tree trunk into the cabin through the door has a lot more potential death threat, a metal door is metal but how thick can a door be?

[scathing]

Your average Joe, who's never seen any opposite lock, is going to panic (and possibly freeze) the first time their car fails to do what its told. Understeer is safer for them to recover from.

From a power on perspective, they're just going to pop off the gas and maybe steer more. If you're power understeering, the first but should eventually correct the issue. In an oversteer moment you need to use the steering wheel delicately and gradually lift the throttle, which is not something the license test requires you to know. If they don't steer they'll spin out. If they do steer to hard and/or pop off the throttle, the tail will snap and they'll fishtail.

Under brakes, if the car understeers because they've gone in too fast, their slowing down will hopefully get the fronts to eventually fall back into the grip circle. If the tail slides under brakes, they'll have to do that steering thing and stop braking...which is counter-instinctive to most people in a scary situation.

[mosoto]

One word: Skidpan, should be compulsory for every P plater. Get to know your car and what it can do.

[180 wanabe]

I know for sure that when the VDC is on that it will break individual wheels

for example if I turn hard right at a slow speed and jump on the gas to kick the ass out, before it goes into a slide it I can hear it grab the front left break to stop the car going into oversteet as well as reducing the power.

[superspit]

yeah...safety is important, ofcourse.

I tried the '10 second VDC Button hold', and yes, VDC appeared to de-act, as per previous posts. (ie. no dash-light, no further button control).

But upon undertaking some safe 'spirited' take offs, the car's TCS insisted I was doing the wrong thing, forcing my face into the steering wheel.......

Upon re-starting/re-setting the car at the next stop, I manually disengaged VDC (Pushed button-Dash light on), and the TCS appeared to go away, thankfully.

In my 24 years of driving all sorts of buckets, I've never owned such a pretentious system of VDC, mainly it's TCS component.

It may well be one of the factors that will make me sell this car, and get into a <>1970 Mach 1 Stang.

[ther]

Quick question , what are the stock standar rim size for a v35 coupe and the sedan?

Did the coupe only come with stock 18' or some with 17'?

[xscape237]

I personally hit the VDC-OFF button almost everytime i jump in the car.

Nothing to do with safety, its just preference.

Anyway to answer the question above. The 17" was only the AT coupes. MT coupes come with bigger wheels standard.

[n15m0]

getting back on topic...if u do plan to go 245s all around, remember our cars are RWD and hence factory specs were 245 at the rear for traction purposes and 225 at the front for manouverability. If it were an AWD GTR for example then yeah bigger tires all round would have more pros than cons.

[08r3308]

my tyre placard says 235 rear and 225 front

17"stock rims tho

[rs73]

Quick question , what are the stock standar rim size for a v35 coupe and the sedan?

Did the coupe only come with stock 18' or some with 17'?

Most non premium will come with 17"

my premium auto comes with 18" - I've seen a lot of premium autos with 18" in auction...