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Gear ratio guess

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by the professor, Feb 15, 2003.

  1. the professor

    the professor 1/2 ton status

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    Thinking to pick up a trashed 1984, 1/2 ton burban
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    TBI 350/700r4/NP208..10 bolt rear/D44
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    Anybody want to guess what gear ratios this probably has...
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    Not time or place to jack it up and check it...
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    Possiblilty of 3.08..???
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    /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif
     
  2. heavy4x4

    heavy4x4 1/2 ton status

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    Probably 3.42's.....3.73's if it's got the factory towing package.
     
  3. the professor

    the professor 1/2 ton status

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    Well that would be some improvement anyway..unless it has the TT pack...got 3.73's now..was hoping for 3.08's
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    We shall see tomorrow..
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    Thanks.. /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif
     
  4. sdavid

    sdavid 1/2 ton status

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    There are people on here more versed than I am in this area, but a D44 and a TBI 350 are not stock for that year. So no telling what kind of ratios you will get and if they match. Could be as bad as 2.73s or up to 3.73s. Who knows??? Sounds like that one has had some parts changed, could be for the better though.
     
  5. the professor

    the professor 1/2 ton status

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    ???--the TBI looks OEM..there is no data plate, but I thought all the trucks had 5.7L...I have a book in the garage, I will go look..
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    Its a Ca truck, may make a difference... /forums/images/graemlins/truck.gif /forums/images/graemlins/cool.gif
     
  6. sdavid

    sdavid 1/2 ton status

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    TBI=Throttle Body injection, started in the model year 1987 for chevy trucks/K5s/Burbs. 5.7L=350 V8, size of the motor. It could also have a 5.0L= 305 cubic inches. The TBI will be similar looking to a carb while just looking at the engine, but when you take off the air cleaner it will have just 2 bowls with injectors in them.

    There will also be a sticker under the hood that tells you what motor came from the factory. Its on the radiator support and will say 5.0 or 5.7L.

    Many people swap in the TBI for the carb, but you also have to transplant the computer.
     
  7. the professor

    the professor 1/2 ton status

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    I just looked..got guess its 1987..swore the guy said 1984..that even better, upgraded 700r4
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    What you think for front axle...corporate 10B?? Didn't even look under the front.. /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif
     
  8. the professor

    the professor 1/2 ton status

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    Looked that up too..looks like a corporate 10 bolt... /forums/images/graemlins/truck.gif /forums/images/graemlins/cool.gif
     
  9. sdavid

    sdavid 1/2 ton status

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    Yeah if it is a '87, good deal! TBI much better improvement to the carb. It would have the 10B front axle if it is stock. If I had to guess for a '87 burb the ratio would be 3.42 or 3.73 on the 1/2 tons.
     
  10. the professor

    the professor 1/2 ton status

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    One more quick dumb one..anyone know if the 10B in the rear is a 8.20 or a 8.50..and how do I tell without pulling the cover..??
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    Yea, well the TBI is going on my friend '66 stepside..350/700r4
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    REALLY REALLY hope they are 2.73's..would like better than 6mpg at 75mph
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    The transfer and diffs are going into my 1978 K20
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    I know, I know...not as strong..but I don't rock climb..and there are MUCH cheaper and better tires and wheels for 15"
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    Also, I figure to shead 3-400 lbs...maby more.if I include the tires and wheels..(10ply tires are HEAVY)....between the NP205 and the Corporate 14 Bolt...and they DO use the 208/10Bolt.. behind the 502/4L80e's...
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    In any case, it will probably eventualy get a 12 bolt in the rear anyway
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    1978 K20
    1989 burban front clip (all the details)& doors
    1989 burban bucket seat, console, dash, tilt, comboswitch
    overhead console radio
    2" body
    6" chassis
    1989 454 4bolt crate motor
    eddlebrock manifold, 800 q'jet
    headers
    all ca smog equip, dual cats, x-over, 2.5 in throuh
    crane cam &springs
    roller rockers
    MSD billet HEI dist
    MSD 6a /remote coil
    TH400 (wide ratio 2.71 first gearset)
    14bolt, corporate, floater...3.73:1
    2200rpm converter
    NP205
    33-12.5x16.5 mud tires
    16.5x9.75 chrome spoke wheels
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    REALLY,REALLY tired of the howling tires...
    -0-
    can't hear the GD stereo on the freeway /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif /forums/images/graemlins/thumb.gif
     
  11. heavy4x4

    heavy4x4 1/2 ton status

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    The rear is the 8.5" 10 bolt - no easy way to tell, but that's what it is.
     
  12. R72K5

    R72K5 Banned

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    8.2 10 bolt was back in the early 70s and before and only under cars anyways, 8.5" was the only 1/2 ton 10 bolt truck axle ever made, the same one as always seen.

    ratio can be anything from 2.73-3.73, youll have to look in glovebox at the spid label or find build sheet or pull diff cover
     
  13. wrathORC

    wrathORC 1/2 ton status

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    8.5" ten bolt. It'll have big square ears at the bottom. It'll be found both front and rear. The little ten bolt found in cars and s-series will have rounded little ears.

    It probably has 3.08 or 3.42 gears.

    Only crazy people want 2.73s or 3.08s. Nobody needs airplane gears unless they're running really little tires (like smaller than stock 235x75r15s). My gas mileage blows with 2.73s. I'm hoping 3.42s will help.
     
  14. the professor

    the professor 1/2 ton status

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    Yea..just picked it up and "drove" it home
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    What a mess, but a cheap mess..friend wet 50/50 on $300..he wants the engine and TBI..I don't need or want the engine..I have a complete w wiring and computer..1989 454 TBI on an engine stand in my garage
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    TBI 5.7L..runs great...(friend putting entire eng and TBI in his '66)
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    Trans works OK..good for rebuild.may try it behind the my 454
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    Shields on transfer and gas tank
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    Transfer works OK
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    Front diff good, 4 shock setup, new calipers and brakes
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    New master cylinder
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    Cluster w/fuel gage I need (no longer availabe)
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    8.0 rally wheels (nice spares)
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    Rear diff..growls, pulled cover, no gear lube..R&P toast... /forums/images/graemlins/frown.gif 8.5 ring gear as predicted...
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    This, however is not a problem..a R&P is a relative cheap fix..the side gears, spiders and carrier are good..will clean it out tomorrow..add gear oil and see how noisey it is for the time being..needs axle seals and probably brakes..will do it after I install it..
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    The very best part is its got 3.08,s..YEA, YEA, YEA... /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif
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    Thanks for all the info... /forums/images/graemlins/thumb.gif
     
  15. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    </font><blockquote><font class="small">In reply to:</font><hr />
    The very best part is its got 3.08,s..YEA, YEA, YEA...

    [/ QUOTE ]

    Wow, thats the first time I have ever seen someone excited to have 3.08's... /forums/images/graemlins/eek.gif /forums/images/graemlins/ooo.gif /forums/images/graemlins/smirk.gif To each his own though. /forums/images/graemlins/thumb.gif
     
  16. sdavid

    sdavid 1/2 ton status

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    Sounds like you got what you wanted and a really cheap price to boot. That's what its all about! One man's trash another man's treasure. /forums/images/graemlins/thumb.gif
     

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