DOES YOUR 997 HAVE A STEERING COLUMN ???
Discussion
Talking today with a mechanic mate and he tells me that the 997 has no steering column. i.e. the steering wheel has no mechanical connection to the steering rack. I said he was talking bo**ocks (after all it is not a Citroen). But he was adament that the 997's steering is effectively electronically and hydraulically controlled and that there is no direct hard link to the steering wheel via a traditionally steering shaft.
Is this fact or fiction. I certainly would not want to rely on gizmo's pointing me in the direction that I would like to be travelling in.
Is this fact or fiction. I certainly would not want to rely on gizmo's pointing me in the direction that I would like to be travelling in.
The rack-and-pinion steering is sensitive and precise, offering excellent contact with the road. Hydraulic power assistance enables easier manoeuvrability, as do the modest turning circle and lock-to-lock travel. While parking requires only minimal steering effort, the directional stability when travelling at speed is comparable with that of a racing car.
Lifted from Porsche UK web site where there is also a picture
Lifted from Porsche UK web site where there is also a picture
"One of the special features on all 911 models is the variable steering ratio. Around the straight-ahead position, the ratio is less direct, enabling smoother manoeuvres on the motorway. Turn the wheel harder, and the ratio increases, allowing easier cornering and parking."
This perhaps does imply some sort of electro hydraulic control?
This perhaps does imply some sort of electro hydraulic control?
ocks. It may be electrically assisted. This is often termed as electric or electronic power steering. This does not make it "steer by wire".graeme36s said:
Talking today with a mechanic mate and he tells me that the 997 has no steering column. i.e. the steering wheel has no mechanical connection to the steering rack. I said he was talking bo**ocks (after all it is not a Citroen). But he was adament that the 997's steering is effectively electronically and hydraulically controlled and that there is no direct hard link to the steering wheel via a traditionally steering shaft.
Is this fact or fiction. I certainly would not want to rely on gizmo's pointing me in the direction that I would like to be travelling in.
Your friend is mistaken... True steer by wire is a whole bag of snakes, and not something that is legislatively easy currently. Obviously, with out a traditional column, the issues on powerloss become safety critical. Also, feedback to the driver is a major issue and obviously something that would not be appropriate for Porsche as it stands.Is this fact or fiction. I certainly would not want to rely on gizmo's pointing me in the direction that I would like to be travelling in.
Maybe he's confused with the variable steering ratio or something?
PS Variable steering ratio is achieved by meerly having teeth on the rack that change their pitch at 30 degrees either side of centre. A close pitch +/-30 of centre for damping of the near straight ahead for 'straightline' stability at speed with a wider pitch further out for increased input and manuverability.
Edited by Pat Cash on Wednesday 26th September 11:26
graeme36s said:
Talking today with a mechanic mate and he tells me that the 997 has no steering column. i.e. the steering wheel has no mechanical connection to the steering rack. I said he was talking bo**ocks (after all it is not a Citroen). But he was adament that the 997's steering is effectively electronically and hydraulically controlled and that there is no direct hard link to the steering wheel via a traditionally steering shaft.
Is this fact or fiction. I certainly would not want to rely on gizmo's pointing me in the direction that I would like to be travelling in.
I appreciate what you're saying Graeme, but surely you do just that everytime you jump onto a aeroplane ?Is this fact or fiction. I certainly would not want to rely on gizmo's pointing me in the direction that I would like to be travelling in.
Edited by Slippydiff on Wednesday 26th September 11:29
graeme36s said:
Talking today with a mechanic mate and he tells me that the 997 has no steering column. i.e. the steering wheel has no mechanical connection to the steering rack.
Does your Mechanic Mate work for AIRBUS by any chance? I suggest he is getting his 997's mixed up with his A320s.... 
Pat Cash said:
PS Variable steering ratio is achieved by meerly having teeth on the rack that change their pitch at 30 degrees either side of centre. A close pitch +/-30 of centre for damping of the near straight ahead for 'straightline' stability at speed with a wider pitch further out for increased input and manuverability.
Thanks for putting it in layman terms, as I never really understood (or tried to). However, does this mean that the steering column is one (and not sliced in two) and runs the same length more or less, whether you have variable steering or not?This system was always heavily criticized on BMW's (active steering, making drifting (don't ask) more difficult to sustain and cornering in general less intuitive). I didn't know it was available on 997's! Is it mandatory, and does it affect handling?
Kay
tonikaram said:
Pat Cash said:
PS Variable steering ratio is achieved by meerly having teeth on the rack that change their pitch at 30 degrees either side of centre. A close pitch +/-30 of centre for damping of the near straight ahead for 'straightline' stability at speed with a wider pitch further out for increased input and manuverability.
Thanks for putting it in layman terms, as I never really understood (or tried to). However, does this mean that the steering column is one (and not sliced in two) and runs the same length more or less, whether you have variable steering or not?This system was always heavily criticized on BMW's (active steering, making drifting (don't ask) more difficult to sustain and cornering in general less intuitive). I didn't know it was available on 997's! Is it mandatory, and does it affect handling?
Kay
The teeth on the rack that it mates with are spaced further apart at each end than they are in the middle - its very simple and not much different from a 'non' variable rack and pinion.
Its not 'active' or electronically controlled just a slightly trick rack and pinion.
Pat Cash said:
tonikaram said:
Pat Cash said:
PS Variable steering ratio is achieved by meerly having teeth on the rack that change their pitch at 30 degrees either side of centre. A close pitch +/-30 of centre for damping of the near straight ahead for 'straightline' stability at speed with a wider pitch further out for increased input and manuverability.
Thanks for putting it in layman terms, as I never really understood (or tried to). However, does this mean that the steering column is one (and not sliced in two) and runs the same length more or less, whether you have variable steering or not?This system was always heavily criticized on BMW's (active steering, making drifting (don't ask) more difficult to sustain and cornering in general less intuitive). I didn't know it was available on 997's! Is it mandatory, and does it affect handling?
Kay
The teeth on the rack that it mates with are spaced further apart at each end than they are in the middle - its very simple and not much different from a 'non' variable rack and pinion.
Its not 'active' or electronically controlled just a slightly trick rack and pinion.
Its standard on all current Porsches - 997, 987 and Cayenne - in fact Cayenne had it from launch if I'm not mistaken.
It's not an electro-hydraulic pump either, just normal belt-driven from the engine. There's nothing special about the basic design of the steering rack or the column.Variable ratio racks have been around for ages. Escorts with manual steering had them. It makes the steering less responsive around the straight ahead position. I don't know why Porsche changed it. Maybe the less enthusiastic drivers didn't like the traditional 911 'fidgit' to the steering. I drove me mates 997C2S and was a bit disappointed by the lack of feel. I was expecting it to feel more alive.
Slippydiff said:
graeme36s said:
Talking today with a mechanic mate and he tells me that the 997 has no steering column. i.e. the steering wheel has no mechanical connection to the steering rack. I said he was talking bo**ocks (after all it is not a Citroen). But he was adament that the 997's steering is effectively electronically and hydraulically controlled and that there is no direct hard link to the steering wheel via a traditionally steering shaft.
Is this fact or fiction. I certainly would not want to rely on gizmo's pointing me in the direction that I would like to be travelling in.
I appreciate what you're saying Graeme, but surely you do just that everytime you jump onto a aeroplane ?Is this fact or fiction. I certainly would not want to rely on gizmo's pointing me in the direction that I would like to be travelling in.
Edited by Slippydiff on Wednesday 26th September 11:29
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