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Is Model Steering fully electronic or is there a steering shaft?

Discussion in 'Model S: Driving Dynamics' started by gene, Feb 17, 2013.

  1. gene

    gene Active Member

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    I have not been able to find an answer as to whether the Model S steering is fully electronic, meaning the wheel is a variable control and its input travels by wire to a responding steering box? Or is there a good old fashioned mechanical shaft from the steering wheel to the steering box? Steering by wire makes me nervous.
     
  2. Doug_G

    Doug_G Lead Moderator

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    Pretty sure it's electric assist. For one thing, the wheel is very hard to turn with the power off.
     
  3. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    I do not believe a fully steer by wire car will pass any regulatory body. The electronics is just in the power steering. If you look at about 1:25, you can see the steering shaft coming from the steering wheel. (Note the video is a bit old, but it's unlikely that this would have changed.)
     
  4. gene

    gene Active Member

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    @Doug, so you are saying with power off, though it is difficult, you can steer somewhat. This would be good news. This says electric assist.

    @Jerry, yes I think I am seeing a steering shaft in the video at 1.25 min, but I'm not sure that is what I am seeing. Thank you for searching that out for me.

    I have a S on order but pure steer by wire would be a deal breaker for me. I just could not enjoy driving the freeway nor a winding mountain road with pure steer by wire as complete and instant steering failure could be possible. I'm hoping steer-by-wire never becomes a reality in cars. My background as a pro-mechanic and amateur engineer keeps me off of fly-by-wire planes and will keep me out of any future steer by wire cars, I'm just too conscious of how things work.

    If I could get even a couple of more S owners to try to turn your steering wheel with power off and check that your front wheels are moving left and right a bit, I would be very grateful.

    Thanks, Gene
     
  5. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    As I said, I don't believe any regulatory agency would allow a steer-by-wire car. There has to be a manual failsafe and you can't do that without a steering shaft. Even Chrysler's side-by-side steering failed to pass muster (not that I think it would have been accepted by the public had it been approved). It's really just the power assist that is electric. The Prius has a similar system.
     
  6. gene

    gene Active Member

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    I was just googling steer by wire today and came across 2013 Nissans to introduce steer-by-wire. Their system has a clutched steering shaft that is supposed to take over in case of electrical failure.
     
  7. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    That sounds like creeping featurism. Why go to the bother of drive-by-wire when you also have a steering shaft.

    Did they say if it was Japan-only?
     
  8. tdelta1000

    tdelta1000 Active Member

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    Like stated before it is power assisted and here's a photo to prove that:
    6210462188_4f82279662_z.jpg
     
  9. gene

    gene Active Member

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    @tdelta: Well that photo is proof, nice to see that steering box there.

    @jerry: I think the steering-by-wire Nissan to introduce steer-by-wire cars in 2013 | Crave - CNET may be for the USA as well. Their idea is that with side sensors on the car and sending units in the lines of the highway that this steering could also keep you from drifting out of your lane and even avoid another car coming your way. It sounds scarey but they talk of the car taking over the steering from you in an emergency maneuver. The backup steering shaft is to have a clutch that will engage if the electronic steering fails. I'd like to know what makes that clutch close (electricity?) and I would want a way to test that clutch's function easily.
     
  10. Robert.Boston

    Robert.Boston Model S VIN P01536

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    Systems like this are usually designed the other way around: there needs to be energy to prevent the clutch from engaging. If power fails, the clutch pops back (through a spring or similar) to its default, closed position.
     
  11. gene

    gene Active Member

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    Ah Ha! That would make good sense. In which case, one may be able to know the mechanical steering backup is working if the wheels steer when the key is out of the car.
     
  12. andrewket

    andrewket 2014 S P85DL, 2016 X P90DL (soon 100)

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    This. Fail closed, as opposed to open.

    A
     
  13. pete8314

    pete8314 Vendor

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    I had my frunk apart last week to install a radar detector....it looks a lot different to this, I guess because its fully populated with all the other mechanicals, but I can 100% confirm its standard power steering.
     
  14. johnsmith

    johnsmith New Member

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    This looks like a ALL ELECTRIC rack and pinion! Not a dual-mode electric/hydraulic rack and pinion. This Rack and Pinion is basically a manual steering unit with power steering by a electric motor - meaning if the electric motor malfunctions, then you better have the strength to turn the steering wheel manually!

    Please tell me if I am wrong. I wish I am wrong as I really want to get a Tesla, but if it is an all-electric rack and pinion, then no way. I had a BMW electric steering malfunction and it was VERY DIFFICULT to turn such a heavy car.


     
  15. Mark Simons

    Mark Simons Member

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    It looks like maybe you've found your reason... Best of luck.
     
  16. elecblue

    elecblue Member

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    And how often does an electric rack-and-pinion system fail? If by some misfortune it happens to me, I'll call the service center and have my car taken there for repair.
     
  17. Jeff Miller

    Jeff Miller Member

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    My power steering assist failed a few days after getting the car. I can confirm that it is still possible to turn the car with the power assist off, although it requires some effort. After I pulled over and rebooted the console, the error message disappeared and power steering was restored. I immediately drove the car to my local service center and they kept it for quite a while trying to diagnose the source of the problem. It wasn't clear in the end what caused the problem so they ended up replacing the steering assist motor. Haven't had any problems since.
     
  18. scaesare

    scaesare Active Member

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    This is no different than any other assisted steering system, such as a hydraulic pump with a belt-driven pulley turned by the engine.

    Belts break. Pumps fail. Hydraulic lines leak/fail.

    In all those cases , while the effort to turn is increased, it's possible. Especially at higher speeds... it's much easier to turn the weels, and you generally don't want to be making terribly sharp turns at higher speeds anyway. If you fail on the highway, you gently veer towards the shoulder. If you are on a mountain road at 30 MPH you'll have to put some muscle in to it, but the same would hold true for any other power-assisted car. Once at lower speed it will be harder to steer, but at that point you should hopefully be out of harms way.

    Actually, I'm going to guess the Model S MAY be easier to steer than the BMW, as there's no engine/transmission weight sitting on the front wheels... but the weight of the battery pack might negate this so I'm not sure.
     
  19. Rodolfo Paiz

    Rodolfo Paiz P85 "Plug and Play"

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    Hydraulics are no more reliable than electricity, and I believe usually less so. Any system can fail, and while the high-quality manufacturers will do their best to make sure it doesn't... a very very tiny number of them will do so regardless of the technology used in them. Basing your purchasing decisions on this kind of fear is irrational and counterproductive for you. Just pick a car you like, from a company you trust, and get on with your life, because your concern will apply to every single car in this market segment. Every. Single. One.
     
  20. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    1. When the hydraulic pump fails in an old fashioned car, it's (usually) hard to steer too.

    2. Strictly speaking the hard steering is really only at low speeds and is controlled by the SAI alignment angle. I don't know the value for the Tesla.

    3. Neither my 2001 Prius nor my 2004 Prius (100,000 and 145,000 miles respectively) ever had an electric steering failure.

    In my opinion, electric steering is more reliable because there are no fluids to leak and no pump or belt to fail--three components vs. one.
     

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