I didn't know the G35C has rear steering.

[mmm def]

http://www.infiniti.com/content/0,,cid-127023_sctid-32005,00.html

 

Click on the bottom middle pic, rear active steer. My prelude had 4ws, that was fun! In a low speed tight turn you could feel the back swinging around..fun!

[wukindada]

Very nice.....Is this a new for 06 option?

Did you happen to see if it is avail on other Infiniti vehicles?

Wifey loves the new M45:)

[Project84]

My '84 Camaro had rear wheel steering too... it was called MORE THROTTLE!!!

 

 

I MISS YOU BABY!!! (she had to be sold)

[mmm def]

Very nice.....Is this a new for 06 option?

Did you happen to see if it is avail on other Infiniti vehicles?

Wifey loves the new M45:)

 

I was just building an 06 it came up as an option for $750. I know they have it on the M45, maybe the G35 sedan will get it? i'll go look.

[rallispec]

i do think thats a new option for '06

 

i wonder how much weight it adds to the car, and if it will make it down to the 350z.

[Guest *Jedimaster*]

My '84 Camaro had rear wheel steering too... it was called MORE THROTTLE!!!

 

 

I MISS YOU BABY!!! (she had to be sold)

My 85 T/A does that too

[Xenonk]

is the car that big you need rear steering?? it aint no fire engine.

[mmm def]

Keefe,

 

Can you explain the advantages of rear steering? I think on my lude the rears would steer opposite up to a certain speed then switch and steer with the fronts. Pretty cool and the car handled great but is it necessary?

[Leonardo]

Monster Trucks have them too!!!

[PGT]

Many cars have passive rear steer which allows the rear suspension to add toe under load.

 

Nissan has been doing SUPER-HICAS rear steer for a long time (since the Prelude days). Didn't the 300ZX have it?

[Leonardo]

yes they did and Stillen had the kit to eliminate that.

[mmm def]

Many cars have passive rear steer which allows the rear suspension to add toe under load.

 

Nissan has been doing SUPER-HICAS rear steer for a long time (since the Prelude days). Didn't the 300ZX have it?

 

Yeah it was a lot of fun in my lude. How does it work to improve handling? By pointing the rear wheels the same way as the fronts (high speeds) I don't see how it would improve...I don't get the physics part.

[ChruiSSer]

A lot of trucks have the rear wheels steering for manuverability in tight places. I think the VR4's had it as well. Honestly, it's just something else to break!

[Xenonk]

Many cars have passive rear steer which allows the rear suspension to add toe under load.

 

Nissan has been doing SUPER-HICAS rear steer for a long time (since the Prelude days). Didn't the 300ZX have it?

 

HICAS, Super-HICAS, and Super-HICAS II was part of the Skyline Family as a premiere thing on TOP of the LSDs.. (as if you can turn and go fast enough already).

 

Keefe,

 

Can you explain the advantages of rear steering? I think on my lude the rears would steer opposite up to a certain speed then switch and steer with the fronts. Pretty cool and the car handled great but is it necessary?

 

 

The advantage of having rear wheel steering is simple. Try driving your car in reverse around the neighborhood.. you'll soon realize it's easier to aim the car where you need to go without using a lot of steering input. Less input for the same amount of degree of motion. Basically you are converting your car from a "wide sweeping motion" into an "oversteer motion" by using rear as the active end. The reason why it's not used widely for consumers is that it can be very twitchy, especially in high speeds because it requires even less input to change directions. Just drive around in reverse, then you can tell me how easy and hard it is to steer the car.. but you will soon realize that it just takes less steering input to get the car pointed in the direction that you need to go.

 

Some people say that the geometry doesnt yield any difference between front and rear steering (which is true), but when you mix in the fact that one of the axles is a fixed direction, that's when your geometry is really different.

 

On a front wheel drive car when driven normally (without any loss of grip to make the car neutral steer or understeer), the front wheels will have a larger radius to cover than the rear. Larger radius = Larger circumfrences = Larger distances to travel = Longer it takes to complete a turn = More time to react to the changes that goes on. At the same time, your rear tires will actually even have a smaller radius to travel (as it wants to become the pivoting point, just imagine if your front tires can turn 90 degrees to the rear tires, basically you will be making front wheel drive donuts in a parking lot and we all know front wheel steering on publicly sold road cars dont even get that kind of angle on the front wheel steering, max would be 40 degrees or so). Imagine you had a fixed front axle, and now your rear is steerable, you just changed the pivoting point of the car to the front of the car. Now add that notion to the fact that we all drive forward and you have to make a turn.. the rear of the car will see a shorter radius while making the same turn, but because you have control of the rear tires, you can change the angle of the rear tires to even make even a SMALLER radius turn than it was able to in the front steering drive car. It's like adding insult to injury..

 

It's the same principles to fire trucks and dual steering vechicles:

http://en.wikipedia.org/wiki/Fire_engine

 

Fire trucks-

 

The turntable ladder is the best-known form of fire truck, but there are also "cherry pickers", rescue tenders, floodlight trucks and other specialized units. A "Tiller" or "Hook-and-Ladder" truck (a semi-trailer carrying a turntable ladder), formerly much used in the United States but are becoming rarer today, requires two drivers, as it has separate steering wheels for front and rear wheels (the steering device for the rear is sometimes a tiller rather than a true steering wheel). This truck is often used in areas with narrow streets that prohibit the longer single vehicle trucks from entering.

 

 

Hopefully, now you can understand why 18-wheelers need to take wider turns (it's so that the rear doesn't clip the inside curb or corner.. rear steering can help eliminate that by turning later and making it's own apex further into the corner OR better yet, share the same turning radius as the front does).

 

So after all, rear toe does have a larger impact the car's handling characteristics than the front toe alignment.

[Xenonk]

Yeah it was a lot of fun in my lude. How does it work to improve handling? By pointing the rear wheels the same way as the fronts (high speeds) I don't see how it would improve...I don't get the physics part.

 

 

it's like your car is doing neutral or oversteering without the loss of grip from the tires to achieve such actions. Your 'lude has what as known as 4WS (4 wheel steering) Google it.

[f1anatic]

I don"t know if it is rear wheel steering like on the Mitsubishi 3000 GT VR-4 or not. That one had the rear wheels steer in the opposite direction ...say front wheels were steering left ...the rear ones were steering slightly right ! - this way the turning radius was smaller (and truth be told at almost 2 tones that car needed it).

 

Other Euro cars have had rear wheel steering particularly models from Lancia and Alfa Romeo and Opel. But it was electronically controlled - using ABS - and braking the inner wheel during a turn - to creat a pivot effect

[Slickvic]

Honda dropped it because it was expensive as hell to repair and the advantages just were not worth the added complexity. And like Cruisser said, its just more to break.

[malfeas99]

I also heard that the earlier versions of 4WS technologies caused seriously spooky wiggling on the highway sometimes.

[Xenonk]

With today's wheel sensors, steering wheel angle sensors, wheel speeds, tranny speeds, accelerometers, etc etc, the car should be better with the changes in rear steering methods. Nissan is trying to get back into the leading edge of technology by going back and mating all the goodies into one car.

 

I remember that Nissan has some really neat stuff such as:

 

Super HICAS II

ATTESSA-ETS-PRO

All Wheel Drive

Twin Turbo

VVL (old version of CVTCS)

 

I can only imagine that time will bring all of these designs back into one car with way better refinement and then some.

[John M]

The 3000GT/Stealth had 4WS through 1995. The Galant VR4 also had it for both years of production.

[godwhomismike]

Interesting.... I wonder if it handles better now with it.

 

Hopefully some auto magazine will test it.

 

A good test would be an '05 without the option vs. an '06 with the option - equipped exactly the same just one with and one without.

[IwannaSportSedan]

I always thought the idea of rear steering was an interesting one.

 

I drove a fork lift for a little while, and rear steering can be a real fun time whipping things around, especially with a very bottom heavy vehicle. (it still tips a bit, though! )

 

The idea for counter rear steering at slow speeds is to make the car behave as if the center of the car is tethered to a center point, and the front and rear wheels follow the same arc around it... shortens the turning radius by quite a bit, as Keefe so well explained.

 

Then as speed increases, the rear steering rate decreases until a break-over point where the rear steering is zero (non rear-steering cars are always zero steering rate, unless they have passive rear steering geometry) and above that speed start to dial in minute amounds of complimentary steering angle. Very small changes needed due to the effect of steering the rear of the car at high speed...

 

The rear tires steering with the front allow the car to move "laterally" at speed. Aiding in lane change maneuvers and such (car's bearing changes less in respect to it's heading... or is that the other way around?... it keeps the car pointed closer to straight forward.)

 

The thing is that a rear steering system has to be tightly controlled due to the physics Keefe describes. play in the mechanicals, slow response of the control system, improper rates, and sometimes just quicly changing speeds and steering angles at the same time can really make a mess for rear steering.

 

With electric cars being conceived with in wheel motors, drivelines will be changing, and stepper motors, computer controls, etc... become more common and more capable, some of these technologies may come back into use in a more adaptable and consistent way.

 

With varying wheel speeds individually using in-hub electric motors, not only will AWD be easier, but so will braking (recooperative-energy braking, smooth anti-lock and traction sensing) 4-wheel speed dependent steering as well as independent wheel angle steering, and real-time suspension damping, rebound, and geometry adjustment are not inconceiveable in the future.

 

Good on Infiniti for offering it as an option on the G35. It is an interesting technical feature, and as long as it isn't standard, people who don't want it, don't have to have it. (I wish lots of other things in the Auto industry were like that...)

[jon_s]

Then as speed increases, the rear steering rate decreases until a break-over point where the rear steering is zero (non rear-steering cars are always zero steering rate, unless they have passive rear steering geometry) and above that speed start to dial in minute amounds of complimentary steering angle. Very small changes needed due to the effect of steering the rear of the car at high speed...

 

 

Great description~! This is exactly what my '88 Mazda does. The effect is very noticeable and results in more-neutral handling and easy parking maneuvers. And it makes for seriously fast lane changes.

[godwhomismike]

I would strongly look into a G35c if and only if it offered an AWD option

 

AWD plus active rear steering would be an interesting mix.

[SubieDriver]

Keefe,

 

Can you explain the advantages of rear steering? I think on my lude the rears would steer opposite up to a certain speed then switch and steer with the fronts. Pretty cool and the car handled great but is it necessary?

 

I almost bought one of the AWS Preludes.

 

The thing I really liked about Honda's version was that it was so much simpler than the ones that calculate speed/steering angle/etc. using computer control.

 

Honda's was a simple mechanical linkage that caused the rear wheels to turn the same direction as the fronts for the first several degrees of steering wheel travel (although the rears turned fewer degrees than the front), then, as you turned further, the linkage would straighten out the rears, then cross over into opposite turn angle.

 

At higher speeds, turning the rears in the same direction as the fronts increases stability when making lane changes. You wouldn't have large steering inputs at high speeds, therefore the mechanical linkage wouldn't shift into opposite input on the rears.

 

When you make sharper turns (the assumption being that you would be travelling slower), such as right-angle corners or pulling into a parking spot, the linkage would give opposite angle to the rears to help bring the rear end around the corner more quickly, giving a much smaller turning circle.

 

It was a rather ingenious design, I thought. I suppose not enough people understood the value of it, so they didn't sell enough to keep it on the market.

 

I wonder if that was the same problem with Subaru's Hill-Holder Clutch? Not enough people understood the value, so it didn't stick around. I thought that was a rather ingenious design too, but good design doesn't always mean success. After all, Betamax was superior to VHS, and VHS stomped all over it in the marketplace.

 

Subaru is that way too. We all know that Subarus are well-designed cars, and will stomp the competition in performance, but we're relegated to a niche because other brands have slicker marketing campaigns.

 

Look at Windows vs OS/2. OS/2 was a clearly superior OS in its day, but Microsoft stomped it into the ground through marketing.

 

Sometimes the good guys win though. The world is starting to wake up to the fact that the AMD CPUs are superior to Intel CPUs, and people are seeing that Subarus are better cars than most of the competition.

 

Life is getting better!

 

Tim