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28 vs 30 spline 8.5 carrier, guts interchange?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by SVO1, Nov 4, 2002.

  1. SVO1

    SVO1 Registered Member

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    I tried searching with no luck.. I have a 90 Suburban 4x4, and the carrier broke (where bearing presses on) that led to broken teeth on the ring gear, and some housing damage..
    I am looking at buying a 28 spline complete rear end (used) and was wondering if I can use my posi guts to change the 28 spline to a 30 spline, so I can save re-drilling the axles for my 6 lug wheels..
    Thanks for any info!
    ps anyone near Iowa have a 3.73 geared 10bolt rear for sale cheap with 6 lug axles?
     
  2. SVO1

    SVO1 Registered Member

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    bump!
     
  3. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Yes, you may use your 30 spline inners on the 28 spline case. There is only 2 cases for a 8 1/2" 10 bolt, (1) for 2.56 gear only and another for 2.73-5.57 gears. No difference other than being 28 or 31 spline which is only a matter of changing the side gears and spider gears.
     
  4. thebigdaddyof2

    thebigdaddyof2 1/2 ton status

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    Damn, I wonder if they had a bad run in 1990 on the 3.73 ratio 10 bolt carriers???

    I have Hustler's '90 Blazer in my garage right now. He thought it just had a bad ring & pinion....but after disassembly, I found the carrier actually split where the bearing gets pressed on. This is a 30 spline setup.

    I thought I would just use a front 28 spline setup till I found the 30 spline shafts will not fit into the 28 spline carrier. Even if you did change the side gears, the shafts will not fit through the hole in the carrier. The hole has been bored out larger to accept the 30 spline shafts. I believe this is the reason they failed- they are really thin in this area. I'm searching for him a new carrier now....

    What axle did you buy that you would have to redrill??
     
  5. SVO1

    SVO1 Registered Member

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    I was under the assumption (after looking at an 84 4x4 Burb) that the earlier ones were 5 lug, and not 6 lug. If so I would need to get 6 lug axles so I could use my wheels..
    I was looking for just a carrier (had little luck) and now I realize I need the whole assembly.. Sad to say I am ready to torch this thing!!! /forums/images/graemlins/wink.gif
     
  6. thebigdaddyof2

    thebigdaddyof2 1/2 ton status

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    You had to of been looking at a 2WD burb. As far as I know, GM never put a 5 lug 4x4 out.
    I just found a 3.73 10bolt rear out of an '86 burb....gonna check to see if the carrier will swap from it tomorrow. Good luck to ya.

    If you find a carrier, I have a set of 3.73 gears for a 10bolt....they just happen to be on the 28 spline carrier though. They could be swapped over.
     
  7. imiceman44

    imiceman44 1 ton status

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    You beat me to him.
    /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
    5 lug = 2wd
    6 lug = 4wd
    except the very early ones, and I don't know exactly which year but I know 55 had six lug on the 2wd.
     
  8. 88sub4x4

    88sub4x4 1/2 ton status

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    I may have a 10 bolt 30 or 31 spline (not sure which it is but will check) at work. I will see if I still have it. It is a original equipment gov. lock unit out of a 98 tahoe and i think it would fit your app. I will check tommorow for you.
     
  9. thebigdaddyof2

    thebigdaddyof2 1/2 ton status

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    Well,
    I found out tonite that somewhere between 1986 and 1990, GM opened the hole in the carrier AND turned the end of the axle shaft down less- allowing 30 splines instead of 28. This is no doubt when they moved the weak spot from the axleshaft to now the weak spot being the carrier. I'd take the axle shaft failure over the carrier anytime!

    My plan to fix this blazer is to swap the ring/pinion/28sp carrier/28sp axle shafts from the '86 into the '90 housing. Only thing I still need to verify is that the axle bearings are identical. I measured the axle shafts where the bearings run and they appear to be the same. I'll call A/Z tomorrow and let ya know. I'm also gonna make a post and see if anyone knows for sure when the change was.

    Jay,
    What this means to you is: If you find an older axle setup- SWAP EVERYTHING. If you find a set of 28sp axle shafts, my extra 3.73 setup should work for you.
     
  10. thebigdaddyof2

    thebigdaddyof2 1/2 ton status

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    After swapping in 2 axle shafts, the carrier, the ring and pinion, new pinion seal and two new axle seals, Troy Moore's (aka Hustler) '90 Blazer is back on the road. All parts swapped in were from a 28 spline, 1986 model and worked out perfect.
     

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