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Help... 12 bolt pinion setup ** solved**

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Thumper, Nov 5, 2002.

  1. Thumper

    Thumper 1/2 ton status

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    Does anyone know the torque specs for the pinion nut on a 12 bolt 8.875"? Especially with a new crush sleeve? I have a bit of play in the pinion (in and out), and I think the crush sleeve isnt crushed therefore holding the bearings out a bit from seating into the cups. How much torque should it take to crush a new sleeve?
    Thanks
    Mike
     
  2. imiceman44

    imiceman44 1 ton status

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    Re: Help... 12 bolt pinion setup

    You should have checked the torque withan inch lb wrench on the pinion and matched that.
    I hope someone has an idea of that range.
    You should tighten untill you get a slight drag on the pinion. That is what you need to look for not the actual torque on the nut.
     
  3. Thumper

    Thumper 1/2 ton status

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    Re: Help... 12 bolt pinion setup

    Well, I cant get close to the preload torque until the pinion is seated in the diff properly. What I am asking is how much torque is it going to take to crush the sleeve to the point where the pinion is tight in the diff. There is no point in checking the in/lb preload until everything is in place right?

    Mike
     
  4. Thumper

    Thumper 1/2 ton status

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    Re: Help... 12 bolt pinion setup

    Never mind... I called The Gear Center in the city and he told me that its a lot. tRusty agreed also that its lots more than 150. So I just went to the local shop and got under her and came onto that bolt and voila, it tightened. I think it was prolly closer to 250 for future reference. As soon as I ended up with no slop, the preload was good too. Weird how that works huh? I think I screwed up when cause when I set up the diff, I used the old bearings and old crush sleeve like normal, and when I put on the new bearings and new sleeve in, I torqued it to what I had read (silly me) and wondered why it wasnt fitting right. So, thats the story. Alls well that ends well!
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: Help... 12 bolt pinion setup

    Cool deal Mike...I knew it was more the 150 lb/ft.

    Rene
     
  6. Mudzer

    Mudzer 1/2 ton status Author

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    Re: Help... 12 bolt pinion setup

    I have heard it takes in upwards of 300 ft/lbs to crush the sleeve. Did you check your pinion bearing preload with inch/lb torque wrench. This is a Critical setting if you want the gears work properly.
     
  7. imiceman44

    imiceman44 1 ton status

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    Re: Help... 12 bolt pinion setup

    OK mudzer do you know that number or at least the range?
    When I did mine I didn't check it before, so I actually tightened it too much and ended up toasting the bearings.
     
  8. Thumper

    Thumper 1/2 ton status

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    Re: Help... 12 bolt pinion setup

    Well, the way I did it after the initial screw up is tightened the nut to crush the sleeve. Like I said, I think it was near 250 or above to get it tightened enough. I turned it enough that all the play was taken out of the pinion... in and out that is. Then I took the inch lb torque wrench (dial type) and turned the diff. You should have 10-15 in/lbs while its turning. But, I think thats without the carrier installed. I believe (the way I read it) that the torque has to be right with just the pinion, no carrier. I tried mine today with everything installed except tires (I wasnt removing the axles and carrier just for a loose nut) and I had prolly 50 in/lbs to turn it. I figure thats pretty good. It doesnt make any noise which is the main concern of mine. Like I said, my screw up happened when I went from the old bearings and crush sleeve to the new ones. I just torqued the nut to the value the paper said, and didnt realize that the sleeve hadnt crushed. When I took it for a drive it made a noise when I went from on the gas to off the gas. So I checked it out and found the pinion loose and moveable in and out near 1/8". So, There I was... but its fixed now! /forums/images/graemlins/smile.gif

    Mike
     
  9. imiceman44

    imiceman44 1 ton status

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    Re: Help... 12 bolt pinion setup

    Ok thatnks for the numbers.
    I think those are reasonable numbers.
    Maybe next time I take off my driveshaft to change U joints I will check mine and see if you were in the ball park.
    I like to have these numbers handy somewhere. When that happened to me when I changed a yoke from a 10 bolt to a 12 bolt, I didn't know about the crush sleeve, and I thought it was supposed to be tightened to250LB. and that's how I learned the hard way how you can toast a bearing.
    /forums/images/graemlins/frown.gif
    I am glad you caught it before some major damage was done.
    /forums/images/graemlins/thumb.gif
     

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