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Thread: Gear Swap

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  1. #1
    Join Date
    Jun 2007
    Location
    Brampton, Ontario
    Posts
    2

    Gear Swap

    Have been reading alot, but this is my first post. Would like to change 3.42/ G-80 to a 3.90 and Trutrac. Have noticed most are 3.73 or 4.10 in this range, and was wondering if it was a tuning issue or are 3.90's just unpopular ? My cam is stock but I plan on a mild upgrade in the near future.
    Thank you in advance.
    2004 RCSB 4.8 Tuned, TBTC, Corsa Touring
    2009 Equinox Sport

  2. #2
    I was going to go with that same gear swap and agonized over it for months before going to the 3.73s. BUT, I wanted to do this for towing a camper. I wound up getting 2 255/65/16 tires along with the gear change. when I plan on towing the camper I just swap the 65 series tires from the front to the back. The 1" difference in diameter brings me very close to the rpms I would be turning with the 3.90s. When I'm not towing I don't pay a penalty in mileage. It works fine for me.
    Bob

  3. #3
    Join Date
    Mar 2009
    Location
    Cromwell, CT
    Posts
    256
    3.90s are a good in between gear but they are more money than 3.73s or 4.11s. $50-60 more.
    01 ecsb 5.3 4x4 z71
    Avalanche 17s and a pant load of miles

    61 Corvette
    350, 4 speed, 4.56's

    32 Ford 4 door sedan
    keeping it "stockish"

  4. #4
    Join Date
    Jan 2009
    Location
    New Orleans
    Posts
    61
    Im changing my gears from 3.42/g-80 to 3.90 trutrac! ha I'll let you know how it is.
    04 Silverado Ls
    lq4 swap, electric fans, 228r, 243, K&N Cai, LPP, EFILive, FLT, yank 3000, trutrac, 3.90s

  5. #5
    Join Date
    Jun 2007
    Location
    Brampton, Ontario
    Posts
    2
    Quote Originally Posted by wholeshot View Post
    Im changing my gears from 3.42/g-80 to 3.90 trutrac! ha I'll let you know how it is.
    Great ! Good luck with your install. I'll be watching.
    2004 RCSB 4.8 Tuned, TBTC, Corsa Touring
    2009 Equinox Sport

  6. #6
    Join Date
    Mar 2008
    Location
    Burleson, Texas
    Posts
    389
    I plan on going from 3.42 to 3.73 soon. Should make a bit of a difference.
    '00 Silverado 4.8L (Gone)
    '11 Silverado 4.8L

    Quote Originally Posted by RUFFNECK View Post
    ...First relieve the pressure before doin' that or else you will get a nasty squirt and may get in ur eye.

  7. #7
    Join Date
    May 2009
    Location
    Plainfield, IL
    Posts
    2,036
    3.42 to 3.73 isnt worth it imo...i did it (swapped rears, cuz new one had a locker) the couple hundred rpm isn't enough to really help
    blown transmissions are about as useful as 97% of the guys on this forum

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