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Should I re-gear from 3.73 to 4.1 or lower w/ 33" tires and 700r tranny.

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by shum1, Nov 30, 2000.

  1. shum1

    shum1 1/2 ton status

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    Should I re-gear from 3.73 to 4.1 or lower w/ 33\" tires and 700r tranny.

    I have a 1990 sub w/ 350 tbi and 700r tranny. Right now I have 31" tires, it goes pretty good but driving up the canyon to ski everyday causes my tranny to constantly drop into 2nd to maintain 45mph. This seems a little busy. I'm gonna lift and put 33's on her. I do tow a boat in the mountains and want better performance. I plan on getting some form of crate motor (vortec or 383) but my 120k motor runs very strong now. Should I get 4.1 gears or should I go even lower. I'm kinda bummed at the prospect of gear swapping only one level higher, especialy when my rear was just rebuilt. Should I have the axles/diffs rebuilt or just have them swap gears? I dont do too much hardcore wheeling, mainly just mountain roads. Thanks
     
  2. blazen91

    blazen91 1/2 ton status

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    Re: Should I re-gear from 3.73 to 4.1 or lower w/ 33\" tires and 700r tranny.

    My K5 has a 350, 700r4, 3.73's and it's great on flat land. But if I hook up the trailer or go up a hill, it's a slug. My 86 Sub. has a 350, 475(400 out of a moter home),4.10's and when it was running well, it pulled hills and the trailer very well. O-ya, the K5 has 33's and the Sub. has stockers(measures out to 31"). I am going to 4.56's in the K5, but leaving the Sub. alone. Hope this helps.

    blazen91
    Protect the land FOR the people
    <font color=red>Not FROM the people</font color=red>
     
  3. Blazer79

    Blazer79 1/2 ton status

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    Re: Should I re-gear from 3.73 to 4.1 or lower w/ 33\" tires and 700r tranny.

    I'd say you re-gear to 4.1 gears, since you'll be towing in the mountains. You might get away with your current setup, but the next thing you'll be bummed about will be your tranny. Get a tranny cooler too, It'll protect it when towing.

    <font color=blue>//////
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  4. JimmyDie6.2

    JimmyDie6.2 1/2 ton status

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    Re: Should I re-gear from 3.73 to 4.1 or lower w/ 33\" tires and 700r tranny.

    I have 3.42s with 33s and its a slug. I can't put it in overdrive until at least 65 miles an hour. And if i have to slow down to 55 in overdrive i'm taching at around 1500. My .02 cents, go with 4:10s, I am..........js
     
  5. Rob 85K5

    Rob 85K5 1/2 ton status GMOTM Winner

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    Re: Should I re-gear from 3.73 to 4.1 or lower w/ 33\" tires and 700r tranny.

    I have a 350, 700R4, and 3.73 gears.
    I really don't have much problems at all but the motor I am running makes about 300HP.
    3.73 to 4.11 is not that big of a jump, only 10%. Some other things may be done to your motor to improve the power range, rather than a grand on front and rear diffs. Try headers/exhaust, manifold, ignition, or even a cam.
    These are things that I would do cause I know how, and could save on the labor.


    Rob 85K5

    <font color=orange>Bleedin' Chevy Orange</font color=orange>
     
  6. 6.2Blazer

    6.2Blazer 1/2 ton status

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    Re: Should I re-gear from 3.73 to 4.1 or lower w/ 33\" tires and 700r tranny.

    Going to 4.10 gears isn't much of a jump, and if you put 33" tires on it then you will be right back where you started with the 3.73 gears and stock tires. Since you do have an overdrive trans, I wouldn't hesitate to jump to 4.56 gears. The combo of the 33" tires and the O/D will still give you good rpm's while cruising on flat ground, but should also help out when pulling grades in 3rd gear.
     

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