In another forum post from last week, user 'skuplist' uploaded a video (link) of the rear axle steering action on a 991 Turbo. We've shot a comparison video using our GT3 and documented the actual mechanism in action.


The mechanism behind the rear steering action is an actuator that replaces the Track Rod (pictured below). Track rod is responsible for the toe alignment. Replacing the track rod with an actuator changes the toe dynamically.



for more angles of the rear suspension, please reference our suspension navigator (link)

The video is shot at idle. At this speed the movement is greatest and most visible. The rear wheel counter steer up to 50 miles per hour to create an effective wheelbase that is shorter, and making the car more maneuverable. Above 50 mph the wheel steer in the same direction for improved stability.

Enjoy.

 

Interesting, thank you.

 

Does that mean that earlier 991's both CS2 and CS4 could be retrofitted?

 

Retrofitting the actuator would be fairly straight forward. The tougher challenge would be controlling it. If those signals are available from the existing ECU it would be a slam dunk.

 

Didn't the 1990 Honda Prelude have a similar 4-wheel steering gimmick.

 

It isnt new tech, the 300zx and skylines had it as well. Its been mostly japanese cars.