Help on rear end

Discussion in 'Transmission & Driveline Topics' started by hogg, Mar 4, 2018.

  1. hogg

    hogg Veteran Member

    3,143
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    Dec 29, 2000
    pegram,tn.,cheatam
    Finely got to looking at son factory Z 74 posi rear end, It has a bad clunk in it setting on jack stands,I first thought it was the pinon lose . Tried with all my power to titen the nut , could not move it. Took off the rear pan and could see the upper and lower spider gears moving side to side by turning the drive shift back and forth, they move a lot . Also had the orange paint, painted across the main gear like junk yard people use for used parts,so thanking it has been apart. All gear teeth look good to me at this point.Be for i take this thang apart , what will i need to be looking for? Cause and will there be a fix? Thanks for any,and all input ,
     
  2. camaro71/holland

    camaro71/holland Veteran Member

    968
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    Aug 27, 2003
    The Netherlands
    When does it clunk? Going into reverse or forward? Could be (excessive) back lash. But start first with the easy checks like your drive line. How are the U-joints doing? No play there?
     
  3. Zspoiler

    Zspoiler Veteran Member

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    May 6, 2012
    Federal Way, Washington
    Just have it rebuilt.That way you know its history ,And build it the way you want,Then also a warranty.
     
  4. hogg

    hogg Veteran Member

    3,143
    27
    Dec 29, 2000
    pegram,tn.,cheatam
    As i have said the spider gears are moveing side to side ,like the big pin broke or worn a lot . Isn't it the big pin that holds these in place, and or does the pinon gear keep these in place? When going from forward to revece turning the drive shalf by hand,Hell all the gears mAYBE A MIS mATCH. we have never had it drive able yet.
     
  5. camaro71/holland

    camaro71/holland Veteran Member

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    Aug 27, 2003
    The Netherlands
    Ok, two options. The pin doesn't change/weare, so you're looking at friction plates which have worn over time (very acceptable in a posi) and/or shims not filling up the space as they should.
     
  6. big gear head

    big gear head Veteran Member

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    Central City, Ky.
    A short video would help a lot.
     
  7. djorgensen3

    djorgensen3 Veteran Member

    348
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    Oct 15, 2009
    Peoria, Az
    The pin does wear. I have one here that has noticeable wear on it in the center where the axle buttons rub(flat spotted) and where the spider gears turn on the pin. I changed mine out just recently but honestly it didn't feel a whole lot better with a new one...lol. I also found a shop here in Phoenix that has different thickness c clips to help alleviate some of the gap between the axle and center pin.
     
  8. big gear head

    big gear head Veteran Member

    5,986
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    Jul 30, 2001
    Central City, Ky.
    Excess clearance between the axle and cross shaft is usually due to clutch wear or incorrectly shimmed clutches.
     
  9. hogg

    hogg Veteran Member

    3,143
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    Dec 29, 2000
    pegram,tn.,cheatam
    Big gear head, should i knock out the big S spring,how hard will it be to get it back in, to look at shimmed clutches , I went ahead and pulled the posi unit out to check things out.I thank this has been out befor . Very good looking teeth on ring gear and all others,Only had one shem on each side of unit at side for axel bearings, could this be right? bearings look very bad , going to knock out pion some time this week,stamped on ring gear ,,1G 3984831 12 41 7 7 3 , is this right for 1974 10.5 posi rear? I am thinking maybe someone replaced the ring gear and never did the crush sleve thing. i should have checked the back lash but didn't, could this have been a lot of the slake or clunk ? thanks for any help , I know i will need new side bearings and might as will change the pinon bearings out. Where should i get this stuff from. I will take apart the clutches if you tell me to and try an take pictures.. thanks again
     
  10. hogg

    hogg Veteran Member

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    27
    Dec 29, 2000
    pegram,tn.,cheatam
    Anybody know what DIa. of pin for 8.5 rear?
     
    Last edited: Mar 16, 2018

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