Gmc hydra-matic ?

Discussion in '1947-1954' started by sberman, Dec 28, 2013.

  1. sberman

    sberman Member

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    Seems to shift fine and run ok but when i slow down it is real noisy. Is that normal
     
  2. Greg_H

    Greg_H Member

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    I don't think so. Mine is not any noisier slowing down. Call Gene at restorationhydramatics.com and get his input.
     
  3. sberman

    sberman Member

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    Ill try on monday
    Thanks
     
  4. vwnate1

    vwnate1 Member

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    Hydromatic Drive

    It depends on what you consider really noisy .

    The shifting tends to be more abrupt than other automatics but that's a very good thing , part of why they last forever .
     
  5. Bill Hanlon

    Bill Hanlon Member

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    Put it into neutral and then slow down. Is it still "real noisy"? Remember that these trannies have a rear pump that works off of the output shaft any time the truck is in motion. It makes noise that is hard to hear over normal engine noise, but is pretty obvious with zero throttle, especially out of gear.
     
  6. sberman

    sberman Member

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    Ill try the neutral thing. It shifts good no slipping just when im slowing down feels like the truck is going to rumble apart but only as im slowing could it be brakes ? Or someting else im missing
     
  7. Blueflame236

    Blueflame236 Member

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    Drive axle unbalanced

    Hey there

    You could drive a bit first and have a helper from inside the cabin to use a kind of stetoscope on the surface of the gearbox to locate the noice ?
    Then I `ll suggest you`d lift the entire truck up from the ground with the rear free-wheeling, stay in the truck and start up the truck , then put it in 1st and second gear and back to neutral and listnen if there still is any noise ? Maybe the axle knots ( u-joint) are worn out and have become unbalanced , check this out using your hands if there is any play in them ? These mecanicall issues can give a resonance in your gearbox when gearing Down ?

    Martinius.
     
    Last edited: Jan 1, 2014
  8. sberman

    sberman Member

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    Thanks blueflame
    This has a torqtube so not sure if that could do it or not. But i wll chevk
     
  9. vwnate1

    vwnate1 Member

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    Rumbling

    That makes me think loose or worn out U-Joint .
     
  10. sberman

    sberman Member

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    How do you get in to check the u joint ?
    Fluid was low that helped some. But still loud when slowing down speeding up is no problem at all
     
  11. vwnate1

    vwnate1 Member

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    Torque Tube U-Joint

    You have to drain it then slide back the forward part of the torque tube to see ~ then checkthe bushing for slop as well as the trunnions for wear , slop and loose bolts .

    It's *very* common for the tiny bolts holding the trunnions to the yoke , to come loose .
     
  12. sberman

    sberman Member

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    Ok thanks ill be checking that
     
  13. Blueflame236

    Blueflame236 Member

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    play U joint ?

    I am not excactly shore how much play is acceptable in the U- joint trunnions . Our host have repair kits if needed.

    Good Luck:)
     
    Last edited: Jan 2, 2014

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