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What Gears?

Discussion in '1982-Present GM Diesel' started by 79k5blazer, Apr 19, 2004.

  1. 79k5blazer

    79k5blazer Registered Member

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    Hey, I am in the process of building an '84 Blazer with a 6.2/700R4/208 combo and am in the process of chunking the factory 10 bolts and putting in a 14 Bolt FF in the rear and a Dana 44 up front (no money for a 60) and am at a loss on what gears to run. A few guys I have talked to have told me not to go to low a gear because I dont want to over rev the engine but according to Randy's Ring and Pinion with the over drive gear on the 700R4 that 5.13s will work for 37" tires at 70 miles and hour. It says I would be running 2,348 RPMs. I would sure love some input, because this is all i have left on my buildup! thank you for all of your help in advance!!

    Ryan - Fort Worth, Texas
     
  2. Pookster

    Pookster 1/2 ton status

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    5.13's are just fine. But it has been said that max fuel economy is between 1900 and about 2200ish. Given that most larger highways have a 65mph designation (and out east, flow of traffic is usually +10mph of whatever it is designated). Ususally you have to go at 75 just to keep out of the big rigs flying by.

    The other thing is, 4.56 gears are easier to find- especially if the axles are out of the military vehicle.

    5.13's on a 10b front might be deadly as well. You sure can put a lot of force on 5.13's.
     
  3. mcinfantry

    mcinfantry 1/2 ton status

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    im running 4.56 gears, 38.7" tires and an OD nv4500. im happy, but maybe should have gone 4.88
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I run no OD and 4.56's with 39.5's. On the freeway I rarely pass anyone and it's revving at ~2600 rpm. I know the motor will rev more without complaining, but I hate listening to it. I'd gear it to cruise at 2100 or so in OD...that should give you the best of both worlds as far as max comfortable cruise speed and mileage as well as decent off road performance.

    rene
     
  5. 79k5blazer

    79k5blazer Registered Member

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    Well guys I really appreciate all of your advice, it has helped me get over this dead spot in my build-up.

    Ryan - Fort Worth, Texas
     

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