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4.10 gears and 33's

Discussion in 'Performance and Tuning' started by Volcom21, Feb 17, 2012.

  1. May 13, 2012 at 3:37 PM
    #81
    DevL

    DevL Well-Known Member

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    Taller tires will still hurt your fuel economy. Has little to do with rpms, but not how you think. Taller tires means lower rpms... which means the fuel cut off ends sooner and you don't roll without out fuel going to the engine while coasting as much. You will press harder to go uphill, harder to maintain speed, etc. It is a balancing act and the default gearing from Toyota is damn near optimal for our trucks in stock form. My REAL highway milage with taller, heavier, and wider tires went from 21-24 stock to 16-17 100% highway after my lift. I am almost never able to coast without gas going to the engine because of the lower rpms. I have to be doing 80+ to get any gas free coasting.

    4.10 gears will boost my highway milage.
     
  2. Jun 28, 2012 at 1:20 PM
    #82
    neegdogdig

    neegdogdig Tacohollic

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    Sas Auto-5Spd 4x Trd SC 4.88 gears K&N CAI
    Alright guys, here is the Formula for regear :



    RPM = MPH x Gear Ratio x 336
    Tire Diameter (in)

    Got this from Fearless Gear Inc.

    n also i had 4.20 on my 02 Taco 4cylinder 4x4 running 33x12.50x15 Toyo Tire Open Country M/T n i still do 70, 75, or 80 with no problems. RPM is around 2700 +/- But i'm still not happy so I regear mine with 5.29, with this gear ratio i can almost zoom like a sport car:D. Rpm is not much of a different just save more $$$ for gas:) in another word the truck is now consume less gas better Mpg.
    hope this clarify some confusions that you may have.
     
  3. Jun 28, 2012 at 4:48 PM
    #83
    BradyT88

    BradyT88 ┌∩┐(◣_◢)┌∩┐

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    That formula is way off. I don't know where 336 came from but that will vary from transmission to transmission, hell even gear to gear if you are talking crawl speeds vs hwy speeds.

    EDIT: I just did some math and that formula is actually right, sort of. For the gear ratio you need to factor in both the diff gear and the tranny gear. So in my case I just take 4.88x0.716 and plug that in for the gear ratio to get my 5th gear rpm at various speeds.

    This calculator is much better: http://www.grimmjeeper.com/gears.html
    The 5 speed auto is the A750F, the 6 speed man is the RA60F, the 5 speed man is the W56. Can't remember the 4 speed auto and I am not sure of the 1st gen trannies.

    Also I have 33's and just went from 3.73's to 4.88's. My rpm went from about 2000 at 75 to 2650 and I lost about 2 mpg on the freeway. From what I can tell, I should be using less fuel on inclines and getting up to speed, but I believe it takes more throttle to maintain those extra 650 rpm plus I lost my ability to pretty much coast at all. Ultimately that lack of coasting is what I blame for my loss of mpg's. When I let off the throttle it slows down much faster than it used to which means I am back on the throttle sooner than I used to be on declines and such. I'm sure it also doesn't help that at 75 mph when it down shifts to 4th I am running over 4000 rpm. Takes some extra fuel to maintain that kind of momentum.
     
  4. Jun 28, 2012 at 8:54 PM
    #84
    johnnym

    johnnym Well-Known Member

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