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suspension shims

Discussion in '60-Series Wagons' started by 85fj60, Mar 24, 2004.

  1. 85fj60

    85fj60

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    ???

    At what point do shims become necessary in installing a lift kit? If I were to install 2.5 inch springs and 1.5 inch shackles, would the axles need shimming and if so, by how much?? Would this be done to the front and back??
     
  2. woody

    woody unhelpful spotter Staff Member Admin

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    A good kit will include required shims, best if they are built into the spring pack during assembly.

    Course, many people add a shackle at the same time, or other custom tweaks, and shimming is required.

    Shims only come into play in the front if you drive with the hubs locked in. Since 99% of your driving on road will be with them unlocked, you won't experiece driveline issues.

    Shims in the rear are necessary if the alignment of the t-case output and the diff input are not aligned/angled the same. See http://www.4xshaft.com for lotsa pics in their tech corner on how to measure.
     
  3. dd113

    dd113

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    Shims are a necessary evil. I really dont agree with Woody on this one. If you have any extended shackles you need shims. The amount of shackle will determine the amount of shim needed. The amount of spring lift will also influence this amount. You are changing the castor angle as you move the spring around up and down. As castor changes the steering geomentry will change and influences how it handles. This becomes so extreme in SOA trucks that a cut and turn of the knuckles is required for it to steer correctly.

    Generally, 2.5" lift with stock shackles does not need shims but it also depends on the springs. OME, for example, has a flat spot for the axle to sit on which reduces the arch and helps keep the pinion level. The entire plan is to keep the pinion at the stock attitude. As you lift the truck the pinion rotates upward. The pinion is just used as a refrence point as the real issue is with the inclanition of the knuckles.

    There are a lot of ways to figure this out exactly. I dont fool with that.

    General rule of thumb:
    any 2.5" lift 2' or 2.5' shims
    add any shackles to above 4' shims
    higher lift or really long death shackles go 6'

    Most all trucks will differ. I generally toss on 4' shims for most applications
     
  4. lovetoski

    lovetoski SILVER Star

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    I have experience with my fj60 only. I have a MAF 2.5" lift, with OME shackles/shocks. Wandered a lot - esp on the freeway. (Other than play in the steering box, the steering is tight.) Added 4 degree shims...amazing difference. Steers pretty straight now.