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How strong is a 12 bolt

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by blazingboy, Apr 30, 2003.

  1. blazingboy

    blazingboy 1/2 ton status

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    Well guys the 10 bolt finally went boom with the 33 inch tsls now I can't decide to go with a 14 bolt or a 12 I think that 14 would be over kill. I don't do heavy wheeling just some trails and some mud and a heavy foot on pavement. So will a 12 be strong enough and also will it bolt right in. Also did they come with 3.73's stock.
     
  2. JHG

    JHG 1/2 ton status

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    I know that the 14 bolt is stronger, and if I would be changing I would choose the 14 bolt. I have heard a storys for years that I should not use anything bigger than 35" with 12 bolt, so I figured I would use my 12 bolt (and dana 44) until it would brake down....

    But....I have been using the same 12 bolt under my 1981 K5, with 38" tires, 4.88, lockers, and healthy 350 cid for many years. It was there when I bought the truck 7 years ago and had been there for at least 7 years before that (it might have been with it from the factory). It has only once left me stranded.

    That was because a shop forgot to put a oil into the housing after it had drained all the oil of it. I drove it for 3 months with no oil /forums/images/graemlins/shocked.gif until it broke down.

    I could proof my case and the insurance company of the shop did pay for the damage /forums/images/graemlins/deal.gif so now everything inside it is new

    I used my truck as a daily driver and use it a lot for wheeling. Now I only use it to wheel /forums/images/graemlins/cool.gif

    So I think 12 bolt should be strong enough...but it is much cooler to have the 14 bolt /forums/images/graemlins/wink.gif

    Jon H. Gudjonsson
     
  3. Butch

    Butch 1/2 ton status

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    My K-5 had a 12 bolt with 35's in it from 77 till last year when I went to one ton and 38's. The 12 was the factory 12 from 74, for the last five years had a detroit in it, and for the last 2 a doubler without breaking it. With 33's it should last as long as the truck.
     
  4. rawhead

    rawhead Registered Member

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    My '79 has a factory 12 bolt and it's plenty strong. I run 35's. I have changed the axle shafts out for some chromoly ones just for peace of mind. Superior Axle offers the whole rear kit (2 shafts, lug nut studs, bearings and seals) for $299. It's a good option if you don't want to go to heavy 1 Ton items.
     
  5. Chris_T

    Chris_T 1/2 ton status

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    And yes, some came 3.73 stock
     
  6. BlazinRojo

    BlazinRojo 1/2 ton status

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    Does a 12 bolt bolt right up and does it have the same lug pattern as a 10 bolt (6 on 5 1/2 I think)?
     
  7. Rolled

    Rolled 1/2 ton status

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    I did the swap and the only thing different was the e-brake and the yoke. I switched the brakes to solve that problem and had a different yoke welded on the drive line when I had it lengthened. I could have just replaced the yoke on the rear if I was thinking.
     
  8. COCHEV

    COCHEV 1/2 ton status

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    [ QUOTE ]
    for the last five years had a detroit in it

    [/ QUOTE ]

    did you have the full carrier detroit or a drop in locker?
     
  9. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    [ QUOTE ]
    I did the swap and the only thing different was the e-brake and the yoke. I switched the brakes to solve that problem and had a different yoke welded on the drive line when I had it lengthened. I could have just replaced the yoke on the rear if I was thinking.

    [/ QUOTE ]

    What's the difference with the e-brakes? /forums/images/graemlins/confused.gif
     
  10. Beast388

    Beast388 1/2 ton status

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    It all depends on the wheeling you do. It sounds like a 12 bolt will work for you, based on the wheeling you described.

    For me on the other hand, I've already broken my 12 bolt once, spent too much fixing it, and am now prepping 3/4 ton axles to swap in. I wheel on trails and in the mud with my heavy Burb on 32's. /forums/images/graemlins/thumb.gif
     
  11. Sandman

    Sandman 3/4 ton status Author

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    I ran one with 38's for years and blew it only once. I think you would be fine.
     
  12. bajaviking

    bajaviking 1/2 ton status

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    I just did this and it bolts right up, all you need is conversion u-joint between the driveshaft and the 12 bolt. It's about 19.95 in autozone and I think the part number is 1330.
     
  13. ColAdo82K5

    ColAdo82K5 1/2 ton status

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    make that conversion joint... 3-3130 at autozone
    Blake
     
  14. bee32

    bee32 1/2 ton status

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    Does this apply to all 12 bolts? I am about to do this myself. They have one at my local autozone for 14.99.Thanks!
     
  15. blazingboy

    blazingboy 1/2 ton status

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    Ok guys I think I will just go with the 12 bolt I believe it will do all I need to do. Now I just got to find one.
     

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