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Question regarding 14 Bolt FF pinion / yoke nut

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Eric M., Jan 20, 2003.

  1. Eric M.

    Eric M. 1/2 ton status

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    I needed to swap the yoke on my 14 Bolt FF. It seems the pinion nut which holds on the yoke also determines the preload on the crush sleeve for the pinion bering assembly. I didn't want to torque it too tight and exceed the preload, but after a week it was apparent it wasn't tight enough (the nut loosened). So, I got under there and torqued it down pretty tight.

    I'm worried it may be too tight for bering preload and the crush sleeve. I can't believe this nut sets both the preload AND holds the yoke on, but that's what it looks like from the manual I have.

    Am I missing something here? Is there a torque spec for the yoke? Is there another nut responsible for the preload? Am I going to burn up my berings?


    Thanks,

    Eric M.
     
  2. TX Mudder

    TX Mudder 1/2 ton status

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    I had a similar problem. I messed up my yoke on my 14 bolt and got another one. I removed the nut, swapped yokes, and put the nut on hand tight. Then I founf out it determines preload.
    What I did was just get it pretty tight (150 ft lbs, I'm guessing) and used red loctite. It worked fine and did not screw up my bearings. I may just been lucky as others have claimed to have screwed up the pinion bearings.

    Unless you want to set up the gears again, I can only suggest red loctite and crossing your fingers.
    HTH.
    -- Mike
     
  3. Eric M.

    Eric M. 1/2 ton status

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    That's a pretty foolish design for GM to come up with. This means that if you ever need to change the pinion seal, you should redo your gear set up and replace the crush sleeve in the pinion cage.

    I might try the cross your finger method ... but with my luck, I'll be 300 miles from home when something goes!


    Thanks,

    Eric M.
     
  4. R72K5

    R72K5 Banned

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    with a new GM crush sleeve and torque wrench you should be good to go, you dont want ot hardly crush the sleeve at all as finalization seeting, only just begit to crush it to get preload that will stay put for the bearings and thats enough, kinda tricky really..

    good luck
     
  5. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    This is very easy to fix.
    Go to a dealer and buy a new crush sleeve and seal.
    Now remove the pinion support from the axle housing via the 6 retaining bolts.
    Now remove the pinion nut and flange.
    Replace the old crush sleeve with a new one and install a new pinion seal.
    Now install the pinion flange and start to torque the pinion nut in small amounts at a time.
    You will now need an inch pound torque wrench.
    You need to check and see what the inch pound reading is to maintain a rotation of the pinion gear. If it isn't enough preload then you need to tighten the pinion nut a little more and recheck the inch pound setting. Keep doing this until you have achieved the proper preload on the pinion bearing.
    Now reinstall the pinion support and pinion gear back into the axle housing with the 6 bolts and existing shim(s) and you are done.
     
  6. Blazer1970

    Blazer1970 1/2 ton status

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    4X4 high is correct. To do it right you need to install a new crush sleeve, and re-set the pinion bearing preload to spec. If you are in a pinch, you could clean the parts really good, use some red locktight, and torque the nut to somewhere around 150 or so lb-ft. Just make sure you do not tighten the nut enough to crush the sleeve any more than it originally was, or you will have too much pinion bearing preload, and you will smoke the bearings.
     
  7. guest

    guest Registered Member

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    /forums/images/graemlins/grin.gifYou do not use a Torque Wrench, you'll need a TORQOMETER
    Snap-On Tool
     
  8. imiceman44

    imiceman44 1 ton status

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    Hey eric, there was a thread on torquing this nut a couple of weeks ago, if you PM Ryan B he can give you the numbers. or do a search and get all the numbers and scenarios you can go with. You can actually tighten it to the right spec without replacing the crush sleeve, you need to get the preload right though.
    And to do that you need a torquometer, and get the preload within 20-30 inch pound if I remember correctly.
     
  9. 6.2Blazer

    6.2Blazer 1/2 ton status

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    Well, GM must not be the only "foolish" ones then as this setup is pretty common on anything using a crush sleeve. It would be pretty difficult to make a design that uses a separate nut just for the preload.

    The proper way to replace a yoke on a crush sleeve design is to record the rotating torque of the pinion prior to removing the yoke, replace the yoke and retighten until the same rotating torque is achieved. In the real world, you can probably just tighten up the pinion nut really tight and be fine because of the huge amount of torque it takes to actually change the preload (by crushing the sleeve more). When I rebuilt my 14FF, it was taking over 350 ft-lb. of torque to crush it so I don't think 150 ft-lb will affect anything.
     
  10. Eric M.

    Eric M. 1/2 ton status

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    Well,

    I decided to do it the "Right" way. All the GM manuals and gear stores (Reider and Randy) said to replace the crush sleeve. I figured as long as I was doing all that, I might all well replace the pinion berings and races since I had a new set sitting around. It took about 3 hours, a good portion of which was spend grinding off the inner bering. I couldn't figure out a way to press it off and non of my pullers would do the trick. I ended up spending over $200 for a dial type in/lbs. torque wrench. I couldn't find a cheapy anywhere. And also broke a $60 vise while torquing that darn pinion nut - it takes a lot. If you ever have to do this, be careful not to tighten too much after the pinion cage has no more play. It doesn't take too much to get the correct turning torque for the pinion after that.

    Thanks for the input. Oh, and when I took it all apart, it was apparent, I didn't have it tight enough originally.

    Eric M.
     

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