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Gear ratio?

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by Quetzal_SJ, May 14, 2001.

  1. Quetzal_SJ

    Quetzal_SJ 1/2 ton status

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    Ok I havn't decided on my tire size 33s or 35s any how I would like some input on what gears I should have in the axles. I don't plan on any rock crawling(seen how bad some rigs get beat up) I will be useing my Jimmy as a daily driver it has a four speed in there right now. Sure would like it to be freeway friendly. I have passed up some great deals on dana60s that don't have the gears Im looking for. I have 31tires and 373gears right now and never use first gear. Thats with a 327. I figured when I go to the bigger tire and thro my stroker in there it should be fine. What do you think?
     
  2. Triaged

    Triaged 1/2 ton status

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    3.73's should be fine. That is what I have now. Still has enough get up and go and doesen't rev too high on the freeway.

    '71 Blazer CST with alot of rust
     
  3. Quetzal_SJ

    Quetzal_SJ 1/2 ton status

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    What size tires are you running
     
  4. Triaged

    Triaged 1/2 ton status

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    Sorry I forgot about that. I am running 33's as well.

    '71 Blazer CST with alot of rust
     
  5. gokartergo

    gokartergo 3/4 ton status Staff Member Moderator

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    Check this site out. Go to calculator <A target="_blank" HREF=http://WWW.RING-PINION.COM/>http://WWW.RING-PINION.COM/</A>. I just went to 4.56" and 33. At 65 mph I am turning 2100 rpms. Kinda high but mine is not a daily driver. I probably should have gone with 4.11's But I like the quick pick up off the line LOL
     
  6. 2quicK5

    2quicK5 Registered Member

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    I am running a 400 cid small block with 35" tires and stock 3.73s. My engine has enough torque that my 3.73s do fine. When offroading you can always use the granny low first gear or 4L range for climbing and crawling.

    John

    1972 K5 Blazer: 400 ci, 4 sp, 3" lift, 35" Tires

    2000 Trans Am, A4
    11.97@114 mph
     
  7. 2quicK5

    2quicK5 Registered Member

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    Dan,

    How are you only turning 2,100 rpm at 65 mph with 4.56 gears and 33" tires? I have 35" tires and 3.73 gears and turn 2,300 rpm at 65. My calcs say that you should be turning 2,700 rpm at 65 unless you have an overdrive gear.

    John

    1972 K5 Blazer: 400 ci, 4 sp, 3" lift, 35" Tires

    2000 Trans Am, A4
    11.97@114 mph
     
  8. gokartergo

    gokartergo 3/4 ton status Staff Member Moderator

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    I have the 700r4. Dan
     
  9. Steve_Chin

    Steve_Chin 1/2 ton status

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    I currently have 3.07:1 gears and 32" tires. I am planning on swapping 3.73:1 gears into my Blazer when I put 33" tires on it. It'll be plenty freeway-friendly with the NV4500 I have, but it'd also be quite livable with an SM465.

    FWIW, I'm turning ~1470 RPM at 60 MPH in fifth gear. A 3.73:1 would give me ~1785 RPM at 60 MPH with these tires. With 33s, I'd be turning ~1735 RPM at 60 MPH.
     
  10. UseYourBlinker

    UseYourBlinker 1 ton status

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    I have 3.73 with 33's works great...Off the line fast,and still can drive on the freeway without the motor screaming.



    <A target="_blank" HREF=http://community.webshots.com/user/vwryda>http://community.webshots.com/user/vwryda</A>
     

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