R32 GTR Full-time 4WD

[Oosh]

So anyone who buys an R32 GTR and expects it to handle like a front wheel drive car is going be dissappointed.

They should also be shot!

[Warpspeed]

Hey...... you could always get a GTR and jack it two metres up in the air and fit REALLY big wheels to it. Use it like one of those monster trucks for crushing little cars.

*** Warpspeed runs away and hides *****

[Oosh]

Hey......  you could always get a GTR and jack it two metres up in the air and fit REALLY big wheels to it.  Use it like one of those monster trucks for crushing little cars.

*** Warpspeed runs away and hides *****

RowdyR32 and myself have discussed this often, if money ever becomes a non-issue (we can all dream), then we've both agree that we'll build a R32 GTR bush-basher!

Big wheels, suspension, 5 post bullbar, maybe even a custom station wagon conversion and a roof extension (so you don't hit you head going over big stuff).

You can't tell me it wouldn't be cool! :wassup:

Bring on the :flamed: !

[slow13dude]

Do you think that the 4wd system on the GTR is a bit of a waste of time for the street?  

Cheers

It's raining in Brissy today, ATTESSA got me through some wet patches nicely.

[Laurence]

Thanks SK, that was great. Julian E wrote that the system was designed to reduce front drive when lateral/cornering force was felt by the g sensors, whereas you've said that the ATTESSA kicks in when the rears display slip in comparison to the front...such as that encountered when cornering. I'd have thought that in a power oversteer situation while cornering you'd want more not less front wd (but not enough to understeer of course). Mine certainly feels like it pulls from the front when it gets taily.  Did he get it wrong?

Do you think that the 4wd system on the GTR is a bit of a waste of time for the street?  

Cheers

Lateral G-force indicates that a car has lateral grip so there is no need for the 4WD system

When the car gets slip/yaw the lateral forces will be reduced and the 4WD will increase and all will be well. Makes sense to me...

Might not work in the real world™ but since when have Nissan engineers lived there.

[GTR32]

Lawrence I think I know where you are coming from but not sure I agree with you on that.

Lateral G force does not equate to grip. Lateral g force increases with lateral acceleration since force = mass x accel. A car that corners well can do so at high g before letting go, but the lateral g increases once it loses grip since although mass stays the same, lateral accel increases when it's going side ways. Hence my question about power oversteer and less front wd, as JE suggested, seems strange.

Might not work in the real world™ but since when have Nissan engineers lived there. LOL!

[fatz]

that jjulian guy should go back to driving his hyundi wrx

[Roy]

.... A car that corners well can do so at high g before letting go, but the lateral g increases once it loses grip since although mass stays the same, lateral accel increases when it's going side ways  

Are we sure thats true?

[PHATR32]

so is it possible to use the attesa ecu and snesors on a r32 box, and get an improvment?

steve

anyone?

steve

[Duncan]

Are we sure thats true?

yeah actual G goes mcuh higher just as the spin starts. Say on cheater tyres you can pull 1.1 lateral g, then it lets go and starts spinning, lateral gs go way up, we recorded 1.35 in the gtst at one stage lol

phat32r, did you mean the sensors and control box from later models on the r32? There are a few options for atessa controllers which would be cheaper and more effective, the one we use just changes the % of front bias until at full on it reaches 50/50.

[Roy]

yeah actual G goes mcuh higher just as the spin starts.  Say on cheater tyres you can pull 1.1 lateral g, then it lets go and starts spinning, lateral gs go way up, we recorded 1.35 in the gtst at one stage lol  

Are we talkign spinning or going sideways. Id be willign to bet that once the car starts going sideways the lateral G decreases, remembering that with spinning and the tank slapping effect you will get spikes in G forces purely as a result of the all the unbalanced loads and inertia as the car spins:(

If you put a car on a large radius dry skidpan and drive the thing on a constant arc, the highest G will be achieved on the brink of losign traction, not once you have lost traction and started going sideways...i can draw up a little dynamics sketch to prove the dynamics of it:) ... but in reailty perhaps there are other thigs at play to explain in it????

Not sure, but perhaps differentiating spinning and going sideways is the key

[Duncan]

sorry yes, I definately meant spinning. If you could pull more lateral gs just driving sideways everyone would be going quicker thru corners by drifting. Maybe the tofu delivery boy did discover a new law of physics after all.

[jonn]

anyone?

steve

See attached.

[Gonad Man]

Lawrence I think I know where you are coming from but not sure I agree with you on that.  

 

Lateral G force does not equate to grip. Lateral g force increases with lateral acceleration since force = mass x accel. A car that corners well can do so at high g before letting go, but the lateral g increases once it loses grip since although mass stays the same, lateral accel increases when it's going side ways. Hence my question about power oversteer and less front wd, as JE suggested, seems strange.  

Might not work in the real world™ but since when have Nissan engineers lived there. LOL!

Lateral G forces drop dramatically the moment you lose traction. Lateral g's are a result of the car's ability to push you towards the centre of the curve you are tyring to negoatiate and the moment you lose traction this force drops dramatically.

If you could get more lateral acceleration from losing traction all racing drivers would be drifting.

...Ben

PS-G'day Duncan.

[RedRocket]

Yeah, and drag cars would pull more g's doing burnouts than hooking up at launch...

You might be going sideways off the track having converted some of your longitudinal velocity into lateral velocity, but without as much traction the opposing force will be less, so less g's.

[GTRgeoff]

Yeah sorry D, but what your G sensor has been fooled by is obviously some compounded inertial effects and possibly the location relative to the instantaneous spin centre. Not saying it wasn't measured though. As mentioned earlier, I believe the lateral G sensor will be sensing a lack of rate of change of G and so dial out front drive, but from steering wheel position, differential wheel speed and a change in lateral G that doesn't fit the parameters of the other elements it will determine traction loss and crank in some front drive. I think that will be the key to the Attessa as most closed loop control systems work better on rate of change that a simple integer value function.

It's well known that the friction circle is actually more of an ellipse and is lower in side traction (due to tyre construction limitations) than in front rear, which is also different due to CoG (dominated by engine) location. Now I hope SK doesn't come and tell me I've blown this theory lesson as this is his bread and butter. So my point is you should measure more front/rear G than in any other direction during controlled driving.

[justinfox]

I have the HKS Atessa controller on my R32 GT-R. It's fun to play with it on track. I can adjust it as I am driving so when my tyres start to go I tend to make the car rear wheels drive so I don't get so much understeer!!! I have had the controller on max front torque on Eastern Creek and on corner exit at full throttle you can actually feel the front wheels pulling you out. It's a strange feeling though and the rear just doesn't slide out at all.

I went to Wakefield for the first time in the rain. I had semi slicks on too and almost killed myself on the first corner out of pit lane. It was so damn slippery and scary I almost packed up and went home but I turned on the HKS controller to full front torque (full time 4WD) and wow, car felt AOK around the track. There were a few more GT-R's there and one guy came up to me and said "Damn how the hell were you cornering so fast?! I can't do that in my GT-R!" So there you go, it really works in the wet. I managed to do a 1.15 at Wakefield, first time and in the rain too. Car felt balanced and I even got to take home a trophy for the fastest GT-R of the day.

I love the little thing. It's clumsy by design, doesn't look too hot but it works well.

[Scooby]

So...

Did Julian Edgar get it wrong?

Is 4wd a waste on a street GTR where tyres are unlikely to go off, is it better to ditch the 4 wd and benefit from the weight loss if you're not racing?

[Sydneykid]

Did Julian Edgar get it wrong?

In my humble opinion, absofarkinglutely. :kick:

Is 4wd a waste on a street GTR where tyres are unlikely to go off, is it better to ditch the 4 wd and benefit from the weight loss if you're not racing?

It still rains sometimes (today for example) and there are dirty, greasy, bumpy roads out there in the real world. Then you have the power up capacity, there aren't many chassis out there that can easily handle double the standard power output. R33 and R34 GTR's are certainly more likely (than R32 GTR's) to save your ass if you overcook it. But R32 GTR's are much more fun to drive.

If you don't want to or don't have the skill/training to use it as it was intended, then a GTR is a waste of time. But the same applies to any number of other cars.

[Warpspeed]

Many things have really impressed me over the years. the first time I drove on radial ply tyres (a very long time ago) I thought, wow this is really terrific.

Then I was pretty impressed with disc brakes and multi-point EFI when they became available. My first drive of a turbo car also was pretty memorable too. After owning a couple four wheel drive road cars I would NEVER now consider owning anything else.

If you have to ask the question, you have never driven a 4WD road car for any length of time. Sydneykid has it exactly right (as usual). Even in something really slow like a 4WD Laser, the traction and stability in the wet is awsome.