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Can RWS be manually shut off?

 
Old 03-14-2013, 09:47 AM
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ajag
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Question Can RWS be manually shut off?

AP mentioned he essentially made his decision driving a preproduction car that allowed this. Just curious, would it not be possible as it would ruin the overall suspension geometries?
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Old 03-14-2013, 02:25 PM
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Mike in CA
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I would expect the chance of an off switch is zero. Once you read about how active RWS actually works (most cars including Porsches already have passive systems) it's difficult to imagine why you'd want to turn it off.
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Old 03-14-2013, 03:58 PM
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I can think of no reason why I would want to turn off a device which makes a rear engine car handle like a mid engine one.
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Old 03-14-2013, 04:34 PM
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StatmanDesigns
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Originally Posted by Bob Rouleau View Post
I can think of no reason why I would want to turn off a device which makes a rear engine car handle like a mid engine one.
What about fear and ignorance?
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Old 03-14-2013, 05:49 PM
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It would be like using a duoble negative...
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Old 03-15-2013, 01:43 AM
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Not quite sure what the question here is. In regards to the OP title:

'I did a back-to-back test, in one car with the system able to be turned off by a switch, and couldn’t believe the difference. And on track, the tyres last longer, so you are more consistent.

Originally Posted by ajag View Post
AP mentioned he essentially made his decision driving a preproduction car that allowed this. Just curious, would it not be possible as it would ruin the overall suspension geometries?
Well you can certainly turn the steering wheel without 'ruining' the overall suspension geometries...I would imagine even the rear wheels have to go straight at times regardless of RWS turned on/off.
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Old 03-15-2013, 01:52 AM
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I would think the handling balance would be dangerously out of whack without adjusting the sway bars, etc.
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Old 03-15-2013, 12:32 PM
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Originally Posted by Bob Rouleau View Post
I can think of no reason why I would want to turn off a device which makes a rear engine car handle like a mid engine one.
I agree completely.*


* What's the emoticon for "If you intend this comment to be dripping with sarcasm."?
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Old 03-15-2013, 01:09 PM
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Carrera GT
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Originally Posted by ajag View Post
AP mentioned he essentially made his decision driving a preproduction car that allowed this. Just curious, would it not be possible as it would ruin the overall suspension geometries?
There's maybe five different ways to see the rear-steer product pan out.

If "off" meant to be in a fixed toe angle, I don't see a problem. I've been contemplating how rear-steer (RWS?) works in all the predictable scenarios. Any time the car moves into oversteer (rear wheel overspeed, steering angle) the car's SC/TC "PSM" would have to have a set of parameters to feed to the RWS to say "all amidships" and I presume that means both rears go to a "normal" (symmetrical) toe-in.

Even if the factory wouldn't permit an "off" (for fear of someone doing lap times within a split second of "on" times) I could see an aftermarket solution that simply by-passes signals to the RWS motors and leaves them with a signal that says "we're doing 55 mph and the steering wheel is dead straight ahead ... trust me on this ..."

I'm equally sure there will be an aftermarket that offers an "RWS Delete" kit to pull off all that unsprung weight crap, slot in a lightweight li-ion battery and who cares, faster or slower, if RWS turns out to be stinky, no big deal, just delete it.

What's really interesting is an RWS retrofit to Carreras (surely this will come to the Carreras because it will enhance handling in on-street conditions, understeer, lane change, sharp turns, turning circle.)

Looking at the "variable sway bar" (aka PDCC) which has fallen into disrepute, I think Porsche disposes of PDCC and introduces RWS ... what will it be called .. PAAS? (Porsche Active **** Steering)

Surely the longer Panamera and even the Cayenne will benefit more than the GT cars. PAAS is coming to a car in your garage.

The interesting thing for anyone with a 991 is the new geometry of the GT3, especially the front axle and the programming of the electric steering. Preuninger underscored the point that the GT3 and the Carrera have the same steering and that the differences are entirely in the GT3 geometry. That, to me, suggests they've removed steering stability (you might think of this as simply caster, which causes the car to hold its heading) and steering feedback ratios (input from the driver is amplified to the steering angle action, feedback from the tire is diminished as steering wheel movement.)

Reading into Preuninger's words, the engineers were mandated to be indistinguishable from the 997.2 RS.

This means, in net effect, they returned to the geometry of the 997.2 (wide track, fast ratio, symmetrical feedback to the wheel) using different hardware and compensating for a long production run contract of electric steering racks and a vehicle body they could not alter for the GT cars.

The optimist in me thinks a 991 (at least in the C4 body) could be renovated with GT3 parts bin engineering to give it steering feel and potentially all the wide track goodness.
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Old 03-15-2013, 01:55 PM
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Mike in CA
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Originally Posted by Carrera GT View Post
The interesting thing for anyone with a 991 is the new geometry of the GT3, especially the front axle and the programming of the electric steering. Preuninger underscored the point that the GT3 and the Carrera have the same steering and that the differences are entirely in the GT3 geometry. That, to me, suggests they've removed steering stability (you might think of this as simply caster, which causes the car to hold its heading) and steering feedback ratios (input from the driver is amplified to the steering angle action, feedback from the tire is diminished as steering wheel movement.)
Not entirely. He also stated that the software controlling the action of the electro-mechanical steering had been heavily modified. Keep in mind that despite the electric assist there is still a mechanical connection from the steering wheel to the front wheels. There's no inherent reason why the twitching of the steering wheel we're used to feeling over various road surfaces can't be physically transmitted; the earlier iterations of EM steering were simply programmed to filter them out. A change in programming could fix that.

To your point, the programming could also easily be applied to the Carrera....perhaps in Porsche Sport Steering Feel Package (PSSFP).

Last edited by Mike in CA; 03-15-2013 at 02:32 PM.
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Old 03-15-2013, 02:33 PM
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Originally Posted by Mike in CA View Post
Not entirely. He also stated that the software controlling the action of the electro-mechanical steering had been heavily modified. Keep in mind that despite the electric assist there is still a mechanical connection from the steering wheel to the front wheels. There's no inherent reason why the twitching of the steering wheel we're used to feeling over various road surfaces can't be physically transmitted; the earlier iterations of EM steering were simply programmed to filter them out. A change in programming could easily that.

To your point, the programming could also easily be applied to the Carrera....perhaps in Porsche Sport Steering Feel Package (PSSFP).
That's what I meant by "especially the front axle and the programming of the electric steering" and "steering feedback ratios."

I take it as a given that on-board software is now VIN specific and the guided diagnostic tool is purpose built to constrain "generous" techs in the field from wielding the "golden screwdriver" to turn on features or apply modular updates at their discretion.

Hopefully Mr Porsche will see fit to offer the GT3 steering programming (or elements of it) to improve the steering along the lines of the steering feedback ratios I described (amplifying the user input at the steering wheel, less diminished feedback from the tire to the steering wheel.)

That said, it's the geometry. While the electric steering would be "reprogrammed" it won't make a jot of difference if the geometry is designed to "Cadillac" (as I believe the Carrera is today.) The car is designed to be a confident autobahn cruiser with the automatic cruise control applying the brake, all the driver has to do is stay in the lane while they read emails or play a game that simulates caring for tropical fish.

In other, other words, Preuninger saw the Carrera suspension and said "I can't use any of this!" Seriously. Look under a 991S; it's pretty unpleasant. I've got one and I've spent as much time under it with the wheels off, rather loathing* it, as my wife has spent behind the wheel and loving it (6000+ miles.)

The enormous bulk of PDCC only adds to the "is this a 911?" feeling. I can only hope the parts of the 991 GT3 suspension that I don't like are far less problematic.

* it's still fun.
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Old 03-15-2013, 02:52 PM
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Mike in CA
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Originally Posted by Carrera GT View Post
That's what I meant by "especially the front axle and the programming of the electric steering" and "steering feedback ratios."

I take it as a given that on-board software is now VIN specific and the guided diagnostic tool is purpose built to constrain "generous" techs in the field from wielding the "golden screwdriver" to turn on features or apply modular updates at their discretion.

Hopefully Mr Porsche will see fit to offer the GT3 steering programming (or elements of it) to improve the steering along the lines of the steering feedback ratios I described (amplifying the user input at the steering wheel, less diminished feedback from the tire to the steering wheel.)

That said, it's the geometry. While the electric steering would be "reprogrammed" it won't make a jot of difference if the geometry is designed to "Cadillac" (as I believe the Carrera is today.) The car is designed to be a confident autobahn cruiser with the automatic cruise control applying the brake, all the driver has to do is stay in the lane while they read emails or play a game that simulates caring for tropical fish.

In other, other words, Preuninger saw the Carrera suspension and said "I can't use any of this!" Seriously. Look under a 991S; it's pretty unpleasant. I've got one and I've spent as much time under it with the wheels off, rather loathing* it, as my wife has spent behind the wheel and loving it (6000+ miles.)

The enormous bulk of PDCC only adds to the "is this a 911?" feeling. I can only hope the parts of the 991 GT3 suspension that I don't like are far less problematic.

* it's still fun.
You didn't expect me to read your original comment word for word did you?

Anyway, we agree. With regard to PDCC, although it's appropriate for and works amazingly well in the Cayenne, Porsche did the right thing in not including it on the 991 GT3.
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Old 03-15-2013, 03:49 PM
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They system is going to need to "fail safe" per DOT requirements. I suspect pulling a fuse, sensor or motor wire will make it revert back to straight ahead.

I'll be very disappointed if Pete Stout or some other enterprising journalist doesn't try this for a test when they get their hands on the car.
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Old 03-15-2013, 03:54 PM
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Originally Posted by Petevb View Post
They system is going to need to "fail safe" per DOT requirements. I suspect pulling a fuse, sensor or motor wire will make it revert back to straight ahead.

I'll be very disappointed if Pete Stout or some other enterprising journalist doesn't try this for a test when they get their hands on the car.
Since the 997, attempts to "defeat" systems have results in a "limp home" mode, not a single system shutdown.
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Old 03-15-2013, 03:55 PM
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Originally Posted by Mike in CA View Post
You didn't expect me to read your original comment word by word did you?
Nobody has that much time.
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