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Steering

Discussion in 'Gen 3 Prius Accessories and Modifications' started by rjh427, Apr 18, 2022.

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  1. rjh427

    rjh427 Junior Member

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    Greetings, all.

    My 2011 (Gen 3) has a 106.3 inch wheelbase, according to the Google Oracle.
    My 2014 CX 5 has a 106.3 inch wheelbase also, according to same Oracle.

    What bugs the ever-loving flickers out of me, the CX 5 steering wheel is just shy of 2 whole turns lock-to-lock but the Prius is double that, at just shy of 4 whole turns.

    How difficult/involved/expensive would it be to alter/tighten up the steering ratio on the Prius?
     
    #1 rjh427, Apr 18, 2022
  2. ChapmanF

    ChapmanF Senior Member

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    Simple matter of fabricating a new steering rack with a pinion half the current radius, doubling the torque of the electric power assist motor, upgrading the transistors in its ECU, and reprogramming the skid control ECU for the new steering angles and dynamics.
     
    #2 ChapmanF, Apr 18, 2022
  3. bisco

    bisco cookie crumbler

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    sounds like a full weekend
     
    #3 bisco, Apr 18, 2022
  4. rjh427

    rjh427 Junior Member

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    Well gee, Mr. ChapmanF, that sounds like a piece of pie. I'll wait for more answers if that's okay with you.

    @ everyone else, are there really no compatible steering parts from other Toyota models that will bolt in quickly and easily?

    do not know about upgrading the electric power assist motor but:
    Reprogramming transistors sounds like BS, transistors don't have firmware to be changed. A microchip would, but I'm not grokking why either control unit would need to be reprogrammed. There are rotation sensors for those sorts of things and besides, it's not like these cars spend their whole lives turning left.
     
    #4 rjh427, Apr 19, 2022
    Last edited: Apr 19, 2022
  5. ChapmanF

    ChapmanF Senior Member

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    Hmm, did I say "reprogramming" transistors, or did I say "upgrading" them?

    Transistors don't have firmware, but they certainly have current and power-dissipation limits, and if you go changing a 4-turn gear to one that covers the same range in 2 turns, requiring double the torque, the output transistors built into the original steering ECU are unlikely to be beefy enough for the job.

    Speaking of the steering ECU, any particular reason you changed the word its to "the" while ostensibly quoting me? There are upwards of two dozen ECUs in this car, so "the" is a little on the nonspecific side.

    There is, in fact, a rotation angle sensor, on the steering column, right where the spiral cable is, below the steering wheel. Its readings are used by the skid control ECU, and your proposed mod would change what those readings mean by a factor of 2. That's something that could matter to the skid control firmware.
     
    #5 ChapmanF, Apr 19, 2022
  6. rjh427

    rjh427 Junior Member

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    Did I commingle what you said about the power steering and skid control units? Looks like I did, but you did say reprogramming the skid control unit. I put "the" in quotes because I didn't want to use square brackets, per the usual method of indicating a quote has received grammatic changes. Because the board parses for square brackets and looks for code to act upon. Maybe it does nothing when square brackets are nested inside other square bracket opening and closing tags, I don't know. I've been writing "control unit" instead of "ECU" because "ECU" is "engine control unit" - neither steering nor skid control has an engine. They might have motor controls though so "control unit" seems more correct. A rotation angle sensor, you say. And it's on the steering column, which means it measures whether the wheels are aligned left, right, or straight. So yeah, I can (now) see why that one might need fiddling with. Replaced, provided an acceptable replacement exists. That leaves the follow-up question: are there no compatible, bolt-in parts on other Toyotas?
     
    #6 rjh427, Apr 19, 2022
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