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  1. #1

    Default Help with 3.42s and 35s

    Ok guys, I have a 05 gmc sierra z71 extended cab with 3.42s and 33s. I want to get 35s sometime in the future but ive heard alot about how the gears have trouble pulling those 35s, i was wondering if there was anything i could do without swaping gears that would help when i get 35s. I dont really go muddin much in my truck i just need some something that with help me keep up when i get 35s.

  2. #2
    Master Mechanic
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    your best bet is to change the gears to be safe.i dont think theres really anything else you can do
    -Dylan
    2004 Silverado 4x4
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    1986 K5 Blazer
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    1992 GMC Jimmy "Blue Bomber"
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  3. #3

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    If you go to 35's there's no option other than changing gears (front and rear). If you dont change gears expect poor performance, terrible MPG, and transmission issues.

  4. #4
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    I had 35" tires on my last truck, and it came factory with the 4.10 gears and it ran like a dog. I was going to go with a set of 4.56 gears, but I ended up getting a great deal on a set of Richmond 5.13 gears so that's what I went with. But I definately wouldn't stay with the 3.42 gears, that sounds like what's in my S-10!
    2004 Chevy Colorado
    LS1 5.7 swap/TBSS rear axle swap

  5. #5
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    what about 3.73's?


    2002 Tahoe LT---------TINTED WINDOWS------------7" DUAL DVD INDASH

  6. #6

    Cool Help with 3.42s and 35s

    I have 05 Z-71 crewcab with 35s, truck came with 3.42s. I installed 4.10s but wish I had installed 4.56s like I have I my Suburban with 35s. If you do alot of highway type driving than the 4.10s will be fine. 3.73s are just not enough with the 35s. I wont go any lower than 4.88s in a 1/2 ton because in order to get that many teeth on the small 1/2ton ring gear the teeth have to be thin and shear off easy. There fine on a 3/4 ton truck. You will get better MPG with the 4.10s than if you keep your 3.42s because with a 35 it will just lug the motor.

  7. #7

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    Quote Originally Posted by lancer View Post
    what about 3.73's?
    well see i dont think those years like 05 and up came with 3.73s just 3.42s or 4.10 for the z71s.

  8. #8

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    Quote Originally Posted by silveradotrailblazer View Post
    I have 05 Z-71 crewcab with 35s, truck came with 3.42s. I installed 4.10s but wish I had installed 4.56s like I have I my Suburban with 35s. If you do alot of highway type driving than the 4.10s will be fine. 3.73s are just not enough with the 35s. I wont go any lower than 4.88s in a 1/2 ton because in order to get that many teeth on the small 1/2ton ring gear the teeth have to be thin and shear off easy. There fine on a 3/4 ton truck. You will get better MPG with the 4.10s than if you keep your 3.42s because with a 35 it will just lug the motor.
    ok if i do swap i will probaly go with 4.10s because i have friends will 35s and 4.10s and they do great with them, but does anyone know how much it could run to swap gear ratios to 4.10s?

  9. #9
    Master Mechanic
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    Quote Originally Posted by Duckbuster144 View Post
    well see i dont think those years like 05 and up came with 3.73s just 3.42s or 4.10 for the z71s.

    according to my owners manual my truck has the 3.73's i'll find out by this weekend how my truck does with the 315x70x17's and 3.73 gears


    2002 Tahoe LT---------TINTED WINDOWS------------7" DUAL DVD INDASH

  10. #10

    Default

    I'm in the same exact boat as duckbuster... Putting 35's on eventually and guessing I am gonna have to re-gear to 4.56 from what everyone is saying in this thread. Not trying to change the topic or steal the spotlight, but anyone have an idea on what the full cost of purchasing and getting those gears installed may be?? Thanks


    2005 GMC Sierra SLT 1500 4x4
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    2003 Pontiac Grand Am GT1
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