4 Wheel Steering Porsche

[M.D. Holloway]

http://autos.yahoo.com/news/closer-look-porsche-four-wheel-steering-system-w-140030910.html

Just love the idea of 4 wheel drive 4 wheel steering

[oldE]

They are of course referring to active rear wheel steering.
We all know the 928 had passive rear wheel steering incorporated into what they called the Weissach axle.

I guess it's a matter of degree. (sorry)

Best
Les

[kach22i]

Double Post.

[kach22i]

Double Post

[kach22i]

Originally Posted by oldE

We all know the 928 had passive rear wheel steering

I didn't know that, well I do now.

From the link:

Four wheel steering systems have appeared on about fifty different car models starting in the late 1980s. The two mode, “high-and-low-speed” system has been found on 1991 Honda Accord, ’92-’95 Mazda 929, Mazda RX-7, and many others throughout the years. What is your favorite four-wheel steering car? Tell us in the comments below!

Again news to me, all I can recall is the Mitsubishi 3000GT.


Dodge Stealth cars

[fastfredracing]

I remember the Accords, and there were also Preludes that had 4ws. I worked for a Honda Dealer back then. They were cool to park .

[onewhippedpuppy]

Originally Posted by fastfredracing

I remember the Accords, and there were also Preludes that had 4ws. I worked for a Honda Dealer back then. They were cool to park .

I remember wanting a 4WS Prelude SI as a teen. Cool cars.

[daepp]

Some (POS) Q45's had it. But then again, the Q45 was worthless!

[Chuck Moreland]

Hey, that's our video!

We put that video together about a week ago, and it's been picked up by all types of automotive blogs and websites. Gone viral.

The rear steer is interesting stuff. The benefits for low-speed maneuvers is clear with the counter-steering action, effectively shortening the wheelbase. For high speed (over 80kph) the rear wheels steer same direction as the fronts.

I'm still digesting the benefits of the high speed same-steer action. For the first time we need to consider caster angle, king pin inclination, and ackerman steering for the rear wheels. We have done some measurements and testing to measure /derive these metrics. these parameters can be used to change the rear camber in turns, and in fact the system does just that. This may be the primary benefit of active rear steer.

When driving the car, you are not aware of the rear steering action. It is very transparent. The car handles awesome and high speed turns are confidence inspiring and planted.

Questions remain with respect to long-term reliability. Will the system maintain the required precision? Or will it get sloppy with wear? What are the failure modes? Will tire wear improve, or accelerate? Is there opportunity to improve performance by reflashing the software?

Does it really make the car faster? Don't know since we haven't yet modified the car to remove it. Will the forthcoming RS have it? I'm pretty sure the cup cars do not.

[David]

The best explanation I've heard is the rear steer essentially changes the wheel base. At low speeds with the rear wheels turned opposite the fronts the radius from the centerline of the rear wheels to the turning arc of the front wheels shortens thus shortening the wheelbase. At high speed the opposite happens increasing the wheelbase and high speed turning stability.

[daepp]

Does anyone who buys that car really worry about parking?

[TGTIW]

Wow, with the new Turbo, Porsche really did build a Mitsubishi 3000gt VR4.
4 wheel steer, front and rear active aero, overweight..

[island911]

Originally Posted by David

The best explanation I've heard is the rear steer essentially changes the wheel base. At low speeds with the rear wheels turned opposite the fronts the radius from the centerline of the rear wheels to the turning arc of the front wheels shortens thus shortening the wheelbase. At high speed the opposite happens increasing the wheelbase and high speed turning stability.

Cool

and bump