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Question about A-Tron offset shims/shims in general

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by PetaKane, Jan 19, 2003.

  1. PetaKane

    PetaKane 1/2 ton status

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    I got some A-Tron shims for the back axle that are offset 1.5". Moving the axle back has been no problem the only problem I've had is that the axle doesn't sit all the way back on the shim. The pinion still needs to tip up just a bit. I can't figure out why this has happened I may have missed a step but the hard part is over so now I guess I'm just wanting to know if there is a simple way to get the axle to tip back all the way? Thanks
     
  2. 45acp

    45acp 1/2 ton status

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    Tyler, I do not know all the issues that you may have involved but I will try to guess. Did you use the short bolt in the center hole? The head of this bolt is for centering the block on the spring perch. Did the head of the bolt seat down into the hole on the perch? The hole may be full of crud or even to small. If it is to small just enlarge it with a drill. If I remember correctly the bolt head is 9/16" in diameter. Did you use the long bolt that goes through the springs in the offset hole in the block? This bolt needs to be tight enough to hold the spring pack together. You will need to cut a hole in the top plate that the U-bolts go into 1.5" back from the original placement for the end of the spring pack bolt to fit into. If you did not do this it will make the top plate bolt down uneven. One of these is probably the problem but look into them and if you need more help just ask.
     
  3. TX Mudder

    TX Mudder 1/2 ton status

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    I think what you are saying is that the axle is not rotating the necessary degrees (whatever your block is cut to) so that it will mount flat on the axle.
    My rear axle did the same thing when I installed the A-trons. What I did was was get the ubolts fairly tight, then jacked up the whole rear of the truck by the bumper with a hi-lift. This let the axle 'dangle' a little and let the axle rotate.
    I'm not sure if this a shim thing in general because I've not installed shims before.
    Yes, clean out the hole in the axle perch. I used a screwdriver to really dig out caked in dirt. It was still a tight fir between the shim pin and the hole in the perch for the pin, but I think that's a good thing.
    -- Mike
     
  4. PetaKane

    PetaKane 1/2 ton status

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    Thanks Bill and Mike, excellent replies. Bill, I double checked everything you suggested and everything is good. I made sure to clean out the center hole really well. Mike I think now might be the time for me to go get a high lift jack and try your suggestion. I was thinking something along those lines..how loose can the ubolts be I don't wanna take the chance of the center pins coming outta the hole. Thanks again guys.
    Tyler
     

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