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1/2 ton to 3/4 ton axle swap for rear.

Discussion in 'The Garage' started by Bobby Jennings, Jan 6, 2007.

  1. Bobby Jennings

    Bobby Jennings Registered Member

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    hey all. just bought a 1989 3/4 ton 14bff chevy rear sub axle to swap out with my 1/2 ton 6 lug rear axle, and found out the spring plate's seem not line up with the leaf springs. did i buy the wrong year axle for my 79 chevy stepside. please help.
     
  2. mjnemmer

    mjnemmer Registered Member

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    i ran into that problem when i put a 14bff in my 87 jimmy all i did is torch off the old ones and weld on new
     
  3. sandawgk5

    sandawgk5 3/4 ton status

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    Do the spring plates not line up or the spring perches that are welded on the axle do not line up. If it is the plates (the part that goes on top of the spring pack) are you using the proper plates? You have to use the 14 bolt plates with the 14 bolt as the axle tube is a larger diameter. If it is the perches how far off are they? Mine were off by about 1/4" and I just pulled the spring over by hand and it fit like a glove.

    Ira
     
  4. diesel4me

    diesel4me 1 ton status Premium Member

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    wrong year!..

    I might be wrong,but the only 14 bolt axles that bolt in a 73-87 truck are the 3/4 ton ones from 73-87(or the 88-91 "square cab old style Blazers and Suburbans)...88 and up trucks,with the "new" round cabs, and IFS,have wider axles, and different spacing on the leaf spring pads,but can be made to fit by removing the pads and rewelding them on in the proper locations--be sure the pinion angle is where you want it before you weld them on though!..:crazy:
     
  5. Bobby Jennings

    Bobby Jennings Registered Member

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    i found out that the 3/4 ton 14bff axle is from a 90-91 ifs chevy. it is measured to be an 1"1/2 wider at the drumms. so since i need to change pinnion angle, i will cut the "FOUR" perches off and relocate some new perches. thanks for the info..
     
  6. sandawgk5

    sandawgk5 3/4 ton status

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    That axle will be the exact same width as a front axle so it will correct the staggered look of the tires:waytogo: .

    Ira
     

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