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1091Re: [force_ev] Drive System Problems

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  • Tom Hudson
    Jan 4, 2005
      The pot box is on the firewall inside the engine compartment, if you're
      looking at the firewall from the front of the car it will be on the
      extreme upper right. There is a black box with a couple of silver
      return springs on it and a cable running down. The easiest way to find
      it is to have someone sit in the driver's seat and press and release the
      accelerator pedal. You'll see the potbox shaft move.

      The problem definitely sounds like a potbox issue. What happens is, as
      you drive the vehicle for several years, a certain area on the
      potentiometer in the potbox gets more wear than other areas.
      Eventually, it starts to fail, and the result is a "wobbling" in power
      at a certain position on the accelerator pedal. It happened on my '95
      E-10, and now it's happening on my '97 Force. Basically, you need to
      replace the potentiometer in the potbox -- Solectria might still be
      willing to do this (I bought a new box from them for the E-10). The
      trick is, you need to have it adjusted right so that the pedal position
      is matched to the resistance coming out of the pot.


      Anil Paryani wrote:

      >This is Chris Reeves' former car! It seems the
      >shuddering problem is back. I tried hard acceleration
      >in reverse and it does the same shuddering.
      >I am still wondering about your theory. I have never
      >driven another Soletria but I hear a periodic drive
      >noise that I have never heard in other EVs that I have
      >driven. Is this normal of Solectrias?
      >Where is the "Pot box." The service manual must refer
      >to it as something else. I can check the tolerances
      >of the resistors in the box. But what should they be?
      >--- Mike Chancey <evtinker@...> wrote:
      >>I have been kicking this around a while and I have
      >>some thoughts. I know
      >>this sounds a bit strange, but see if this makes any
      >>The motor speed sensor reads a sensor wheel mounted
      >>on the end of the motor
      >>shaft. The clearance between the sensor and the
      >>wheel is critical. Too
      >>close and they make contact and are damaged, too far
      >>and the signal from
      >>the sensor may become too weak to properly feed the
      >>controller. On the
      >>other end of the motor shaft is a helical gear
      >>driving into the
      >>gearbox. Is it possible that that gear has
      >>developed sufficient side
      >>thrust to wear the motor bearings and allow the
      >>motor shaft to move
      >>slightly back and forth? Under low loads or regen,
      >>the shaft would remain
      >>in the normal position, but under heavy load, the
      >>shaft would move the
      >>sensor disc away from the sensor and cause an
      >>intermittent signal to the
      >>If this does seem like a possibility, then a
      >>possible way of testing it
      >>would be to find a large clear area like a closed
      >>mall parking lot, and see
      >>if you get the same kind of shudder while
      >>accelerating hard in reverse. In
      >>reverse the helical gear action would be pulling the
      >>motor shaft the other
      >>way, say closer to the sensor not further from it.
      >>I am not sure you could
      >>generate the same loads in reverse though, as I
      >>suspect the controller
      >>output is limited in reverse to about the same as
      >>the economy setting.
      >>Is this a particularly high mileage Force? Has
      >>anyone else had any kind of
      >>motor bearing problems?
      >>I had a 1995 Force that I sold in 2003 to a former
      >>EV1 owner in
      >>California. His name was Chris Reeves. Is this by
      >>any chance the same
      >>car? If so that one got new batteries, a new motor
      >>speed sensor, and the
      >>sensor wheel in March/April 2003. It had a problem
      >>with jerkiness at take
      >>off, so I cleaned the pot box and replaced the motor
      >>sensor. That seemed
      >>to cure the problem.
      >>Mike Chancey,
      >>'88 Civic EV
      >>'95 Solectria Force
      >>Kansas City, Missouri
      >>EV List Photo Album at: http://evalbum.com
      >>My Electric Car at:
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      Thomas Hudson
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