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Knuckle centering Real Time help

Discussion in '40- & 55-Series Tech' started by yzftaco, Mar 2, 2007.

  1. yzftaco

    yzftaco Goofy-Goober

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    I'm rebuilding my front end, and am using the do it yourself SST that was posted in Trails a long time ago.

    Post #5 https://forum.ih8mud.com/showthread.php?t=97181

    Question: the indicator maxes out on the top side of the knuckle and when i get to the bottom side there is like 1/8" between the seal surface and the indicator (not even close to touching)

    Do i put lots of shims on the bottom bearing to bring the knuckle down????
     
    Last edited: Mar 2, 2007
  2. yzftaco

    yzftaco Goofy-Goober

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    I tried adding shims to the bottom and taking some off teh top, and the preload went up and didn't really center it either.. although with an 1/8" i would need lots of shims i assume
     
  3. Pin_Head

    Pin_Head

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    You just need to adjust the position of the indicator tip so that you get a reading at the top and the bottom. When the dial indicates the same top and bottom the spindle and seal bores are concentric. Half the difference between the top and bottom measurement is the change in the size of the shim. You have to add the shim to the side that has the closest surfaces and subtract from the sides farthest away, which in your case would be remove from the bottom and add to the top.
     
  4. yzftaco

    yzftaco Goofy-Goober

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    Ok I have one thick shim below and 2 thick and 2 thin above ....... Before your advise i had most below..

    My "tool" when the pins are riding on the lower surface of the knuckle my indicator is reading the lower surface of the seal surface.... from bottom to top therre is a .065 difference.... I zeroed the indicator on the lower and when rotate towards the top the indicator does two turns and .005.. (.0005 indicator with 0-15-0 dial)

    So to bring my preload back up, and to center it.....Should i put a thinner shim below and add some to the top??

    is it un-heard of to have NO shims on the bottom??? Also If I have all the shims up top does that mean the lower bearing has all the pre-load on it??


    I'm going to play with it and see if i can figure this out....
     
    Last edited: Mar 2, 2007
  5. Rocky_LC

    Rocky_LC

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    Distance A - What is it?

    What is distance "A" - Can I measure with an 8" dial caliper?

    Knuckle_Centering_Distance_A_small.JPG

    Thanks

    PS. Where's a good place to buy a "fish scale" guage? I have my old Zebco "Fisherman-De-Liar", but thought maybe I should get something a few d3ecades newer.....
    Knuckle_Centering_Distance_A_small.JPG
     
  6. yzftaco

    yzftaco Goofy-Goober

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    I wish i had the oem SST so i could use that diagram, but that's no what I'm using... thanks though!

    I like how your scale is called a fisherman liar....
     
  7. bigbadshawn

    bigbadshawn

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    have you looked at www.toyota.spx.com? they have an oem centering guage for a reasonable price. better than messing around with a jimmyrig and having to do it all over again.
     
  8. Pin_Head

    Pin_Head

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    Again, it would depend on which way the difference is oriented.

    You have to add the shim thickness to the side that has the closest bore surfaces and subtract from the wide side .
     
  9. yzftaco

    yzftaco Goofy-Goober

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    ok i now have good preload when measuring off the steering arm... and I'm .03 difference now..

    I have one thin on the bottom, and three thick on top...

    I'm worried that the lower bearing is going to take all the punishment with all the shims up top...
     
  10. 67azcruizr

    67azcruizr SILVER Star

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    the OEM equipmenty for centering your knuckle is simple math. OD-ID divided 1/2 for equal shimming. start at the bottom then determine your top per pre load. The job may be tedious but is reletively easy.
     
  11. yzftaco

    yzftaco Goofy-Goober

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    Let me rephrase this.... I'm worried about ALL the shims being on top and none on the bottom... Is the lower bearing going to take all the torque??

    Or does the preload even out between the two bearings when the nuts are tightened even if all the shims are up top??
     
  12. Pin_Head

    Pin_Head

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    Yes, the bottom bearing handles most of the vehicle weight load, but the shim pack thickness has no bearing on this.
     
  13. projektdotnet

    projektdotnet

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  14. 67azcruizr

    67azcruizr SILVER Star

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    You could obtain a correct preload without centering.
     
  15. ArmyFJ

    ArmyFJ

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    But you want it centered so the axle to birfield is straight and comes out centered into the hub.

    Matthew
     
  16. yzftaco

    yzftaco Goofy-Goober

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    ;) That's what I wanted to hear... Thank you