Semi float rear end

Discussion in 'Stock Suspension + Bolt On Kits' started by dirtautoguy, Mar 26, 2019.

  1. dirtautoguy

    dirtautoguy OBS Enthusiast

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    I have a friend who does a lot of recycling mostly cars and such. I was in his yard the other day and noticed he had a Chevy with a 14 bolt semi float rear end. It just so happened I was thinking about swapping my 10 bolt for a 14 bolt in my 96 k1500. And he said I could have the axle if I wanted it.

    I was curious about some things to watch out for with this?

    I figured I would be replacing the axle seals,rebuilding the brakes with new hardware, new spring bushings, maybe new shocks while I got it apart, and a conversion I joint and new axle bearings

    Questions:

    I was reading that sometimes a different a modified drive shaft to fit. What works best?

    What are the chances it’s ready to drop in?

    Are there anything else I should watch for?

    In the case it’s trash would it be easier to get the tools to rebuild it or what is a general cost to have someone rebuild it? (It’s free)


    I won’t be able to get it out untill the snow melts because it is barried in the snow I’m just trying to plan it out a little
     
  2. dirtautoguy

    dirtautoguy OBS Enthusiast

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    Oh. Also do the half tons with 14 bolt rears have heavier duty springs? I’ve heard they do and iv heard they don’t.

    I also need to confirm the gears in it.

    Thanks
     
  3. low4x4

    low4x4 backyard mechanic

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    i did the swap and installed new springs at the same time...the ebrake cable for a long bed reg cab works with the extra cab short bed...the perches on the 14 bolt are shorter so a spacer or a couple extra springs will keep the same height....the difference is about and 1 inch+/-...use new u bolts...I used my factory drive shaft with a combination joint with no other changes
     
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  4. df2x4

    df2x4 Domestics only.

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    That's some interesting info about the spring perch height difference... I wonder if the 454SS five lug semi-floater 14 bolts are the same way?
     
  5. Schurkey

    Schurkey I'm Awesome

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    2WD and 4WD axles have different widths. I don't remember if it's overall width or spring-perch width, just that they're different.

    The 9.5" semi-float has larger axle tubes, needs the 14-bolt U-bolts and plates to install. Maybe that's why the perches are shorter (I didn't notice that they were shorter, but they could be.) Shorter perches on a bigger tube = no real change.

    When I did this, the original U-bolts, washers, and nuts were so rotted I had to buy new ones. No problem re-using the 14-bolt sized plates. I thought I had a photo comparing the size difference between the 10-bolt and 14-bolt plates, but it's gone now.
    [​IMG]

    The 9.5 axle has MUCH better brakes than the 8.5 brakes.

    I put the 9.5 axle on the same springs as were used with the 10-bolt 8.5" axle. Swapped the brake cables to the "new" brakes, and bent new tubes for the brake hose wye-to-wheel-cylinders. Seems to me I re-used the brake hose. Conversion U-joint in the back of the OEM driveshaft. Had to run some emery cloth over the driveshaft yoke, because the yoke was now pushed ~1/2" farther into the trans.
     
    Last edited: Apr 1, 2019
  6. someotherguy

    someotherguy I'm Awesome

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    Dunno about the perches being shorter.

    The spring pack on the 2500 "light duty" is definitely stouter than a 1500. Here's the order:
    1500 has a 3+1 spring pack, 1500 w/HD suspension has 4+1, 2500 "light duty" has 4+1 but the overload leaf is a bit thicker and longer than the 1500 w/HD suspension.

    As mentioned previously the 4wd is wider than the 2wd rear end, by nearly 4". Since the 2500LD is 6 lug regardless of 4wd or 2wd it's a little easier to mistake one for the other if they're out of the truck already.

    Grab the U-bolt saddles that go around the axle housing as they have a larger opening than your 10 bolt saddles.

    BUY NEW U-BOLTS...always. Doesn't matter if the old ones look great. They stretch; this is correct procedure, buy new u-bolts.

    Richard
     
  7. dirtautoguy

    dirtautoguy OBS Enthusiast

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    Great info guys! I’m getting pretty excited and I hope all works out. The snow is melting fast so hopefully I can get a better look at it soon. I’m guessing the stock shocks fit both axles??
     
  8. Schurkey

    Schurkey I'm Awesome

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    Mine did.
     
  9. dirtautoguy

    dirtautoguy OBS Enthusiast

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    CAA0764B-7C15-4CF9-A9DE-8A970C06E3AC.jpeg 4871B74F-A7F7-480B-B4B4-AE79036D1C2D.jpeg I finally went and got that axle today. It wasn’t to bad actually. However the truck was in a stack of cars so I was not able to get a rpo code or anything off it. But the axle was free and he even let me use his torch so I’m not complaining.

    The brake drums and shoes and all that look pretty good I was planning on rebuilding the brakes but I think I’ll leave them alone for now and just replace the seals for piece of mind.

    I pulled the cover off and found what I believe is the famous gm g80. I don’t ave much experience with them but it sure doesn’t look like a regular open diff it has a arm with a spring deal in there too. I’m not real worried about it being a g80 because I don’t wheel it hard or abuse it that way.

    The only couple concerns I have after pulling the cover are:

    1. Gear ratio. My friend said someone else was looking for a rear end in there truck. They had counted the turns of the drive shaft and decided it was a 3.72 which is what I need. However when I pulle the cover off if I under stand correctly it has 3.42 gears :( can someone confirm?

    2.the magnet was in the bottom of the case is that where they go on these semi floaters? There wasn’t much for metal shavings but there was a couple larger pieces maybe 2-3 the picture is of the biggest one in there

    I checked all the teeth and things I could see and they all were good not missing teeth or pieces or even showing much wear.

    Thanks guys
     
  10. Schurkey

    Schurkey I'm Awesome

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    41 / 12 = 3.41666,,, Yup, you captured a 3.42 axle.

    Next question is whether that came from a 4X4 or 2X4, because the width is different.

    Yeah, the magnet just drops into the bottom. Fairly common for it to be fuzzy with tiny shavings.

    If it's from a 4X4, I'd like to have it. Oh, well.
     

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