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8 lug 14 bolt swap...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 89GMCSuburban, Nov 17, 2002.

  1. 89GMCSuburban

    89GMCSuburban 1/2 ton status

    Nov 15, 2001
    Likes Received:
    Thornton, CO
    Alright, I have an 85 3/4 ton Suburban that I want to swap axles with (front 10 bolt and rear 10 bolt to 8 lug front 10 bolt and 8 lug SF 14 bolt). Gear ratios are the same...4.10 ratio.
    Now the problem, I just bought a 4" Skyjacker lift.
    #1 - Will the lift work when I swap the axles since it's for an 88-91 1/2 ton?
    #2 - Will my driveshafts need to change, or just the u-joint?
    #3 - For the front axle...Mine is a 30 spline front, his is a 28 spline...would it be better to swap him the stuff to convert mine to 8 lug than to replace mine with his axle?
    #4 - Can my calipers on my 1/2 ton axle be swapped to the 3/4 ton axle?
    #5 - If not, will the brake lines I bought (fit 87-98 1/2 and 3/4 ton trucks) work on the 3/4 ton calipers?
    Thanks for the help guys! Anything else you can think of, please toss it in!
    Also, what needs to be swapped with him? Just rear U-bolts?
    P.S. The 14 bolt SF is free, a 14 bolt FF isn't. I'll do that later.
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Jul 23, 2000
    Likes Received:
    E-town baby!
    #1...the lift will work fine.

    #2...with a 4" lift the rear shaft should be just fine with a conversion U-joint. The front shaft may need to be lengthened. The majority of people find the front shaft is fine with a 4" lift, but on my buddy's 89 Blazer it needed to be lengthened. The lengthening was pretty inexpensive, approx $75 at a local driveline shop.

    #3...if the gear ratio's in the donor axles are the same as your 1/2 ton axles then swap the 8 lug outers onto your front diff. If the ratio is different then the point is moot.

    #4...Calipers will bolt right up...in fact there is no need to undo the brake lines up front.

    #5...see #4 /forums/images/graemlins/smile.gif

    PS, the SF is a decent upgrade.

  3. BigBurban350

    BigBurban350 1/2 ton status

    Jun 9, 2002
    Likes Received:
    I got 4" suspension on my Burban. My rear drive shaft length is fine, however I have angled blocks. My front drive shaft bolts on, but wears out quicker because of stress on the over extended slip joint. I recently swaped a 14-FF in the rear of my 1/2 ton truck. Everything bolted up in the rear, including the brake lines. I have yet to install the D44 up front w/ 8-lug. NAPA has the conversion u-joint for like $20. Driveline shops dont have jack. /forums/images/graemlins/burb.gif

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