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i know its been posted b4 but...

Discussion in 'The Garage' started by Pow06er, Aug 5, 2005.

  1. Pow06er

    Pow06er 1/2 ton status

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    when going from stock to 35" tires with my stock 3.42s how can i recallibrate the speedo? to read correct?

    Ive read all the stuff about DRAC etc etc i just dont get it.

    Isnt there something i can just go and buy and it will work?

    Its a '88 350 tbi btw
     
  2. Emmettology 101

    Emmettology 101 3/4 ton status

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    Alot of apps you can just change the gear in you t-case that spins you speedo cable to compensate for the change..
     
  3. 91GMCSuburban

    91GMCSuburban 1/2 ton status

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    since your speedo is not electric, I believe your only option is to change the speedo gear.
     
  4. Pow06er

    Pow06er 1/2 ton status

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    is that hard or even worth it? is it easy?

    where can i get the correct gear?
     
  5. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    it is easy to do and most tranny shops can get the gear for you
     
  6. Eric M.

    Eric M. 1/2 ton status

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    Hmmm,

    I'm a little confused. I thought if you had a DRAC, then you did have an electric speedo. If not, you can play around with speedo gears and reducer housings to get the correct reading. See you GM parts dealer and ask him to print the page for your year truck listing all the speedo gear combinations relating to tire size and gears. You'll have to do some math as GM never figured for tires larger than 33". There should be a listing of reducer gear housings as well (1:0 to 1:33 ratio or something like that), they can help out to. These fasten to the transfer case and the speedo cable fits to it. There are usually 2 different gears that can fit in the transfer case that drive the speedo gear. Pay attention to their color (they are identified by color) as the speedo gears can only mesh with one or the other.

    If it is an electronic speedo and you do have a DRAC under your dash, call Technicar 1-800 222-5509 and tell them your tire size and gears and they'll burn you the correct DRAC for around $90.

    Eric M.
     
  7. Thunder

    Thunder 3/4 ton status

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  8. Pow06er

    Pow06er 1/2 ton status

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    wow im lost on all that
     
  9. Eric M.

    Eric M. 1/2 ton status

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    Then I think maybe your best bet is to take it to a shop and have them do the work. Post up for advice finding a shop in your area.

    Good Luck,

    Eric M.
     

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