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1/2 ton and 3/4 ton burb whats the diff?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by sandracer0004, Jan 22, 2004.

  1. sandracer0004

    sandracer0004 1/2 ton status

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    guys i have been in big debate about selling my burb and getting a 3/4 ton 454/400 burb, for towing. currently i have a 350/700r4 burb, with d44/14bff. what are the major differences that distinguse a burb as a 3/4?

    frame
    brakes
    master cylinder,
    proportioning valve?
     
  2. Muddytazz

    Muddytazz 1 ton status

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    The axles are the only difference....althought a 3/4ton 4x4 never came with a factory 454.
     
  3. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    The axles are the only difference....althought a 1/2ton 4x4 never came with a factory 454.

    [/ QUOTE ] fixed it. /forums/images/graemlins/thumb.gif
     
  4. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    I think the proportioning valve is different to compensate for the bigger brakes. I have probs with my big 2.5" rear drums wanting to lock before the front disks on my K5.
     
  5. thatK30guy

    thatK30guy 1 ton status Premium Member

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    [ QUOTE ]
    [ QUOTE ]
    The axles are the only difference....althought a 1/2ton 4x4 never came with a factory 454.

    [/ QUOTE ] fixed it. /forums/images/graemlins/thumb.gif

    [/ QUOTE ]

    [ QUOTE ]
    The axles are the only difference....althought a 3/4ton 4x4 never came with a factory 454.

    [/ QUOTE ]

    Notice Muddytazz said "3/4ton 4x4"? He is right. And no 4x4 Sub ever came from the factory with a 454. Only the 3/4 ton 2wd's came with them. /forums/images/graemlins/wink.gif
     
  6. imiceman44

    imiceman44 1 ton status

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    [ QUOTE ]
    The axles are the only difference....althought a 3/4ton 4x4 never came with a factory 454.

    [/ QUOTE ]

    You're forgetting the springs.
    /forums/images/graemlins/thumb.gif
    Yeah the difference between the 1/2 and 3/4 ton is the 8 lug axles and the springs.
    It's a shame no 4x4 burb came with the 454, you'd think since it was an option on 2wd it would be on 4wd too where you really need it. /forums/images/graemlins/grin.gif
    Anyway I'm getting mine with a TD6.2l
    Picking it up this week end.
    /forums/images/graemlins/pimp1.gif /forums/images/graemlins/pimp1.gif /forums/images/graemlins/burb.gif /forums/images/graemlins/burb.gif /forums/images/graemlins/burb.gif /forums/images/graemlins/burb.gif /forums/images/graemlins/burb.gif
     
  7. sandracer0004

    sandracer0004 1/2 ton status

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    ya i noticed that since i swaped axles my brake light is always on, which is wired to the proportiong valve, i should prob replace it huh?

    also do you guys get a adjustable valve to adjust the rear brakes for disks?

    for lest presure?
     
  8. heavy4x4

    heavy4x4 1/2 ton status

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    Well, just to clarify, '92 - later (the "new" bodystyle) 3/4 ton 4x4 'burbs were available with the 454. But then of course you're not getting a TH400, you're getting it's electronic counterpart - the 4L80E.
    In the generation of suburban I believe you're talking about ('81-91), the only way you could get a 454 was in a 2wd 3/4 ton.
     
  9. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    the only way you could get a 454 was in a 2wd 3/4 ton.

    [/ QUOTE ]
    Thats friggin' dumb. Hmm well I learned my daily 1 thing today. /forums/images/graemlins/thumb.gif
     
  10. SUBFAN

    SUBFAN 1/2 ton status

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    I agree /forums/images/graemlins/frown.gif
     
  11. woody9

    woody9 1/2 ton status

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    um, don\'t forget the frame is different too!!!!

    well, you asked about MAJOR differences, and not sure where you'd classify the FRAME.. but... (as yours is an 89..mine a 91), here's what the 91 spec sheet has on a few things.. /forums/images/graemlins/deal.gif
    16" wheels on SOME 3/4 tons...
    Frame thickness: 1.77 vs 1.92 in
    section radius: 3.57 vs 3.88 cu in
    RBM/Frame: 139,230 vs 151,320 in/lbs (NFI /forums/images/graemlins/ignore.gif what RBM means)
    Those axles also change rear-brakes from 11.15 x 2.75 to a 13.x 2.5 (or 107.42 facing contact vs 116.73 rear) ..
    Front rotors are 11.86 x 1.29 vs 12.50 x 1.29 with 37.63 facing and 42.98 on 3/4s....
    I think those frame & brake differences account for some of the INCREASED tow ratings and such.. /forums/images/graemlins/thumb.gif
     
  12. dremu

    dremu Officious Thread Derailer Premium Member

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    Re: um, don\'t forget the frame is different too!!!!

    My '90 3/4 ton had 16" wheels stock. (Then my wife took it... well, it still has the 16" wheels, but I don't have it /forums/images/graemlins/frown.gif )
     
  13. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    [ QUOTE ]
    [ QUOTE ]
    the only way you could get a 454 was in a 2wd 3/4 ton.

    [/ QUOTE ]
    Thats friggin' dumb. Hmm well I learned my daily 1 thing today. /forums/images/graemlins/thumb.gif

    [/ QUOTE ]

    I have been trying to come up with a reason for this. As far as I can tell this is a late 60's early 70's deal. I think they found the small u-joint D44 and nepco front axles couldnt' handle the torque and were blowing out. Even though they made the D44 a little stronger in 74 with the 297 joints it was never changed. I think in 76 when the D60 became availbel in the 1 tons that you could get the 454 in a 4x4 but the D60 was never available in the burb so never got it till 93-94 (No 454 burb for 1 or 2 years with the body change I have read somewhere)
     
  14. imiceman44

    imiceman44 1 ton status

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    Re: um, don\'t forget the frame is different too!!!!

    [ QUOTE ]
    well, you asked about MAJOR differences, and not sure where you'd classify the FRAME.. but... (as yours is an 89..mine a 91), here's what the 91 spec sheet has on a few things.. /forums/images/graemlins/deal.gif
    16" wheels on SOME 3/4 tons...
    Frame thickness: 1.77 vs 1.92 in
    section radius: 3.57 vs 3.88 cu in
    RBM/Frame: 139,230 vs 151,320 in/lbs (NFI /forums/images/graemlins/ignore.gif what RBM means)
    Those axles also change rear-brakes from 11.15 x 2.75 to a 13.x 2.5 (or 107.42 facing contact vs 116.73 rear) ..
    Front rotors are 11.86 x 1.29 vs 12.50 x 1.29 with 37.63 facing and 42.98 on 3/4s....
    I think those frame & brake differences account for some of the INCREASED tow ratings and such.. /forums/images/graemlins/thumb.gif

    [/ QUOTE ]

    I kinda suspected that but couldn't confirm.
    I know that on the 1ton trucks I can see the difference in the frame thickness but never compared the burb frames.
    Thanks for the acurate info.
    /forums/images/graemlins/thumb.gif
     
  15. sled_dog

    sled_dog 1 ton status

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    my 89 3/4 ton has, 16" wheels, 14 bolt semi floater, and 56" 3/4 ton rear springs.
     
  16. doctor4x4

    doctor4x4 1/2 ton status

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    Re: um, don\'t forget the frame is different too!!!!

    RBM is an abvereation
    R=Rockwell ( a type of metal hardening
    B= (Brinell) a industry standard for measuring the Hardness of a metal aka The Leval - Grade of the Harding ( kinda like a Grade 5 or a Grade 8 Bolt
    M= you guessed it metal
    So there fore the stats show that a 3/4 ton frame is hardened
    151,320 in/lbs -139,230 = 12,090 in/ lbs stronger
    I new that class in Metalergy would pay off some day
    Guess i should have went to spelling class instead
    /forums/images/graemlins/grin.gif
    The Doc
    /forums/images/graemlins/burb.gif
     
  17. R72K5

    R72K5 Banned

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    [ QUOTE ]
    ya i noticed that since i swaped axles my brake light is always on, which is wired to the proportiong valve, i should prob replace it huh?

    also do you guys get a adjustable valve to adjust the rear brakes for disks?

    for lest presure?

    [/ QUOTE ]

    its not pressure as much as it is volume, for the most part.
    pressure is always before a restriction and you want the restriction to all be the calipers and not a kink or something in the line, etc.
     

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