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Alternator rotor spin question

Discussion in 'The Garage' started by Bubba Ray Boudreaux, Jun 14, 2003.

  1. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Let's break it down.

    When I installed my 140 amp alt. during the mockup earlier, the shaft was hanging up when I was spinning it checking for clearance.

    So I checked and double checked and triple checked, I had clearance in a full 360 degree circle.

    So I get the alt. out and spin the rotor some more. The alt. fan is not hanging up, yet is slightly warped (it's plastic). Feels like it's coming from the inside somewhere.

    Should this go away once the alt. is on and running? Should I break it open to see what's going on? Take it back and get another one?

    Thoughts, ideas, opinions?

    By the way, I might do a write up to accompany this swap.
     
  2. chulisohombre

    chulisohombre 1/2 ton status

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    i think it hangs up a little because the bearings have to wear in.i got mine from summit and it did the same thing for the first thousand miles or so.you could turn it by hand but it hung up a little.also you will hear the bearing wearing in with a wirring noise for that fist few hundred miles.at least that is my experience with new alternators.
     
  3. ntsqd

    ntsqd 1/2 ton status

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    Not sure what you mean by hanging up. There is normally some drag due to the slip-ring brushes dragging on the slip-rings. If they are new they haven't seated on the slip-rings yet. Once they have the drag should be reduced, but it won't go completely away.
     
  4. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    When I spin the rotor, there is some resistance in spots that at first lead be to believe that I didn't have enough clearance somewhere. This alternator is a lot larger than my stock alternator so clearance was an issue. Once I pulled the alternator off, the first place I checked was the plastic fan itself, that is what I thought was "hanging up," but on further review, it's coming from the inside.
     
  5. chulisohombre

    chulisohombre 1/2 ton status

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    i also forgot to mention the brushes have springs attached and they rub against the stator to pick up the eclecrical field to produce electricity.on that alternator they are probably twice the size of your stock 60 amp.just like anyt other engine part there is a wear in period where it takes for everything to smooth out.like i said you will hear a wirring noise at first for maybe 400 miles or so until the bearings and all the internals wear in.
     

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