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Converting 6 lug to 8 lug questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by muddin4fun, Dec 13, 2001.

  1. muddin4fun

    muddin4fun 3/4 ton status

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    I need to convert my 10 bolt to 8 lug. Do I have to get a conversion kit, or can I just put new rotors etc on it? Are the knuckles the same? What would I need to do this?

    Don't hit me, Mr. Moderator... I'll go back on topic... I swear![​IMG]

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  2. blazbrnc

    blazbrnc 1/2 ton status

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    You need the 8 lug hubs, rotors, and backing plates. Spindles and calipers can be reused.

    Thank you......Detroit!
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Lara, take a look through the Tech pages. I seem to recall that someone posted an article on how to do this, including GM part numbers. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
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  4. Esteban86K5

    Esteban86K5 1/2 ton status

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    Lara, everytime someone asks this question I usually reply with this LONG explanation that Wes wrote to me when I asked this question. So instead of attempting to rewrite it or re-explain it I just quote him. So here it goes. It's the best explanation I have ever heard for this situation.

    <blockquote><font class="small">In reply to:</font><hr>

    GM has two different types of axles: the "first design" and the "second design". For those who dont know the difference, the "first" goes from 73-76. The "second" goes from 77 to 91. Some differences are:

    1. Backing plates are ALL diffferent. Both 1/2 and 3/4 ton for both designs are NOT the same thing. 3/4 tons are larger diameter than the 1/2 tons. There are currently 6 different types of backing plates. The 1/2 ton has the 73-76, 77-80, and 81-91. 3/4 ton is the same years, but only bigger around.

    2. Bearing hub and rotors are different. There are 4 types. 73-76 use a smaller wheel bearing on both the 1/2 and 3/4 ton. The 1/2 ton bearing hub is an internal drive. 3/4 tons were available in both the internal and external drives. 77 and newer bearing hubs are the same size wheel bearing. 1/2 and 3/4 tons are all internal drives. The differences in the rotor diameter is the fact that the 3/4 tons are larger around than the 1/2 tons. This is why the backing plates are larger around than the 1/2 tons. If you use a 1/2 ton backing plate on a 3/4 ton rotor, the caliper will NOT even align up with the bolts. If the 1/2 ton rotor is used with the 3/4 ton backing plates, the caliper will NOT have enough pad contact with the rotor.

    3. Spindles. 73-76 are one type only. They are "first design" small bearings. 1/2 and 3/4 ton spindles are interchangable. 77-91 spindles are "second design" and all interchangable between 1/2 and 3/4 tons. You cannot use a first design spindle with a second design bearing hub &amp; rotor. The hub will wobble in place. If the second design spindle is used with a first design bearing hub, the hub will not even go on at all.

    4. D44 and 10B axle shafts are not interchangable. The D44 shafts measure: right - 36.13"
    left - 18.31"
    10B shafts measure: right - 35.46"
    left - 19.15"

    5. Steering knuckles. D44's have the infamous "flat top" knuckles on the passenger side. These are good for the crossover steering for where the steering arm is mounted on top of the knuckle after machine work and drilling has been done. The 10B knuckles have NO flat surface whatsoever. Machine work would be excessive to make the crossover work and therefore would be easier and cheaper to locate the correct knuckle off a D44.

    All in all, when doing a swap like this, try to round up the parts off one truck to use on the other. Such parts to swap over would be: backing plates, spindles, bearing hub &amp; rotors, and if desired for crossover steering, the knuckles.

    The knuckles do NOT need to be changed if you do not plan on the crossover steering.

    It all boils down to this: D44 and 10B parts ARE interchangable from the knuckles out. Anything else from the knuckles in is NOT interchangable.

    In Estebans case, he has an 86 blazer and found 73 three quarter ton parts. He would need to use the 73 backing plates, spindles, bearing hubs &amp; rotors.

    ALL calipers on both D44 and 10B are compatible with either axle. Even the first and second design axles are compatible with BOTH 1/2 and 3/4 ton calipers. So, whatever swap you plan on doing, you can retain your stock calipers.
    When stepping up to the big D60, this is a whole different ball game. Nothing is interchangable from the D44 and 10B to the D60.

    <hr></blockquote>

    If this doesn't explain it I don't know what else to say.[​IMG]

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  5. muddin4fun

    muddin4fun 3/4 ton status

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    Awsome! that's what I was looking for. Thanks!

    Don't hit me, Mr. Moderator... I'll go back on topic... I swear![​IMG]

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  6. Rob 85K5

    Rob 85K5 1/2 ton status GMOTM Winner

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    So how I read that is the 85 six lug and the 78 eight lug are the same, minus backing plates, rotor/hub and claipers.
    Which also means I will have some useful spare parts like spindles and axle shafts.

    Rob

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