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Changed my gear ratio.. now have a question and need help

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by rocko, Dec 11, 2001.

  1. rocko

    rocko 1/2 ton status

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    Just swapped out my rear end in my 89.. went from 2.73's to 3.83's..
    Well of course my speedo is off... don't know by how much just yet.. But my questions are... :
    What is the speed difference of this change?
    Where do I get the gear inside the T-case to change the ratio? The guy at the Chevrolet dealership looked at me like I was crazy... I have a light green gear in there now.. indicatiing 2.73 .. I need a White one? and does anyone know the part number.. or have one laying around for 3.73 gear ratio..
    Thanks in advance..


    I haven't failed, I've found 10,000 ways that don't work. www.rocko.rockcrawler.com
     
  2. SCOOBYDANNN

    SCOOBYDANNN 1/2 ton status

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    What TC do you have? If its a 208 tell me how to take it out and ill give you mine----i origionally had 3.73s but after i swapped gears the cable broke.

    Sun Desert Offroad <a target="_blank" href=http://4x4.alloffroad.com>4x4.alloffroad.com</a>

    It's all fun and games till someone loses an eye!
     
  3. Hossbaby50

    Hossbaby50 3/4 ton status

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    In the links section here there is a link for 4lo.com. They have a calculator on there that you can use to find out how far off your speed is.

    My Chevy isn't broken, its just out of gas.
     
  4. rocko

    rocko 1/2 ton status

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    my 89 has a 241 t-case..
    Thanks Scoobydann... email me.. it's on my profile info..

    I haven't failed, I've found 10,000 ways that don't work. www.rocko.rockcrawler.com
     
  5. rocko

    rocko 1/2 ton status

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  6. rick87K5

    rick87K5 Registered Member

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    Rocko,
    I don't know which dealer you checked with, but I've found that the guys at Henna Chevrolet in Austin seem to have an understanding of which gear you'll need to correct your speedo. From what I was told over the phone, they have a few different sizes and can tell you which one you need based on the size of your current gear. Hope this helps.

    rick
     
  7. rocko

    rocko 1/2 ton status

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    Hey there Rick..
    I went to Classic Gmc.. since it's close to my house..
    I'm going to check Henna.. I've alway's liked their part's dept anyway... I need a white gear.. w/ 36 teeth.. so he said..
    So.. how ya been Rick? You still interested in the wheel's and tires I have for sale? Make ya a hell of a deal.. Give me a call sometime.. my cell phone is 512-565-0438


    I haven't failed, I've found 10,000 ways that don't work. www.rocko.rockcrawler.com
     
  8. Nonesuch

    Nonesuch 1/2 ton status

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    on my old 79 the previous owner had put 33's on and fixed the speedo with a little gizmo (transducer) that attached where the speedo cable goes into the tranny and the cable into that. cool little part. I broke it one day and I took it to a chevy parts house and they told me it was 50 bucks. I didnt replace it. but it was a easy way to fix the odometer. if you have a tack in your truck just have buddy do some math with you crusing at certain RPM's to calculate your speed. i think its RPM x tranny ratio x gear ratio (3.73's) x tire diameter. that should give you a close estimate as to how fast you are going. Do that for all the common speeds: 70, 55, 45, 35, and 20 for school zones and you should be set.
     

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