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991 4WS in action

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Old 01-25-2020 | 02:38 AM
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Default 991 4WS in action

Just messing around with my gopro, I tooled around the neighborhood to see the rear steer working at low speeds. I had never seen it before so I thought it would be fun to share.

991 Turbo S Four Wheel Steering
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Old 01-25-2020 | 09:49 AM
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That’s cool to see. Thanks for sharing it.
Old 01-25-2020 | 10:26 AM
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wow...that moves a lot more than I expected....thanks for sharing!
Old 01-25-2020 | 02:16 PM
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Yeah, now that I see it it makes sense that it has to be able to move as fast as you can turn the wheel, or you'll have some weird handling effects at the limit.
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Old 01-25-2020 | 03:30 PM
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Thanks for posting this. I too was surprised at how much it moved. It would be interesting to see it moving in the opposite way at high speeds.
Old 01-25-2020 | 03:37 PM
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I think that will be the sequel. I’ll get around to it next week. What’s the switch to in phase steering? 41 mph?
Old 01-25-2020 | 04:24 PM
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Very cool. Hard to believe it articulates that much. Explains that funky grabing and sound when cold.
Old 01-25-2020 | 04:51 PM
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Originally Posted by Lance 4c
Very cool. Hard to believe it articulates that much. Explains that funky grabing and sound when cold.
Actually all 981/991s crab at full lock with cold tires. Had to do with the amount of Ackerman dialed in and likely packaging constraints with the frunk and macstruts. Four wheel steering wouldn't exacerbate this and may make it better.
Old 01-25-2020 | 05:56 PM
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It's moving more than I thought.. . Thanks for posting.
Old 01-26-2020 | 01:39 AM
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Thanks for that - had no idea there was that much movement, I thought it was only a 'couple' of degrees...

I also like the effect of the wheel as seen through the camera - very cool.
Old 01-26-2020 | 05:12 AM
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Originally Posted by 2fcknfst
Thanks for that - had no idea there was that much movement, I thought it was only a 'couple' of degrees...

I also like the effect of the wheel as seen through the camera - very cool.
You are right. Up to 50kph it goes counter to steering wheels direction up to -3 degrees, and above 80kph in the same direction up to 1.5 deg. This has the same effect as a virtual increase in wheelbase of 500mm which is huge in terms of handling.
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Old 01-26-2020 | 11:01 PM
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I don't know about anyone else, but this really makes me want to film my own rear wheels now just so I can make sure that this system is working on my turbo.
Old 01-27-2020 | 02:29 AM
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Thanks for this, way neat!
Old 01-28-2020 | 11:43 AM
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Fun fact- because of the wide rear fenders, the rear steer on the Turbos can turn as much as 2.5 degrees. The GT3 can only steer 1.5 degrees so the Turbo actually has a shorter virtual wheelbase than a GT3.
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Old 02-15-2020 | 02:38 AM
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I tried to do videos of in phase steering but the problem is that at those speeds (~50+ MPH) you can't really do very aggressive turns at speed on the road and the suspension moves around enough that it's hard to see the steering in action.


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