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12bolt to 14bolt ?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bigmack, Jan 20, 2002.

  1. bigmack

    bigmack 1/2 ton status

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    My truck is a 1/2-ton that has a 12bolt rear end that messed up yesterday. I am wanting to put a 14bolt FF in, mine measures about 42-1/2" between the centers of the spring perch's. Does anyone know if a 14bolt FF out of a 3/4 ton measures the same ? And will I need new U-bolts ? My friend has a 14bolt FF but it measures about 51" between the centers. Would this one be out of a 1-ton truck ? Also I know that I will need 8-lug wheels but do I use a standard backspacing wheel or would I need to get something special.

    Thanks
     
  2. POWERMAD

    POWERMAD 1/2 ton status

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    Oregon
    Your freinds axle sounds like aa 1 ton.
    For wheels I used 15x10 with 4 1/8 backspacing.
    new u-bolts will be needed about $10 ea and a u-joint.
    either a napa 348 or 447


    <font color=green> Too bad ignorance isn't painful </font color=green>
     
  3. bigmack

    bigmack 1/2 ton status

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    Anybody else have info ?
     
  4. 77fixer

    77fixer 1/2 ton status

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    I just got rid of a D70 dually rear and the center bolt spacing was 40 1/2" and the 3/4 ton 14 bolt in my garage is 42 1/2". WMS is 67" on the SRW and about 72" on the DRW. Also the spring width difference between the 1/2, 3/4 ton and the 1 ton is from different spring hangers, the frame widths are the same. When I was at NAPA picking up my conversion u-joint #348, they showed some 3/4 ton rears using the 1310 joint, those would probably be on the 14 BFF with 11" drums. If you want more info let me know, I'll see what I can do. You could get away with 16 or 16.5 wheels on the rear until you convert the front to eight lug. Some people say that your driveshaft might be too long after the conversion, I can't speak on this as I haven't put mine in yet. I got rid of the dually rear because I already had the 14bff, in case you were wondering. If you go with the dually rear you will need different backspacing for the rear or spacers for the front. If I were doing the spacers, I would wait until I converted the front then I think 1.5" spacers would be about right on the 8lug to make the track F&amp;R about the same. My 2 pennies

    <P ID="edit"><FONT class="small">Edited by 77fixer on 01/21/02 04:36 PM.</FONT></P>
     

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