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Rack and pinion...Gear Ratios....HELP?

Discussion in '2nd Gen. Tacomas (2005-2015)' started by spdtaco, Apr 15, 2009.

  1. Apr 15, 2009 at 5:43 PM

    spdtaco [OP] Well-Known Member

    Dec 28, 2008
    North Carolina
    07 5-lug
    265/75/15 BFG Long Trails
    Im just wondering what exactly the rack and pinion is. and i see all the things about gear ratio's. what exactly does the gear ratio mean. and what are the advantages/disadvantages of re-gearing?
  2. Apr 15, 2009 at 5:45 PM

    tacomaman06 Carolina Alliance: Enforcer

    May 1, 2007
    First Name:
    York,South Carolina
    '16 Tundra TRD Pro
    getting there....
    rack and pinion is your steering gear box....................and when people talk of "regearing", its talking about the gears in the rear differential........like if someone gets a big lift/heavy tires, they may need to regear to gain back lost power/mpgs.
  3. Apr 15, 2009 at 6:10 PM

    SC4333 Well-Known Member

    Dec 9, 2008
    First Name:
    San Antonio, TX
    2016 TRD Off-Road 4x4 DCSB - Super White
    Are you referring to a ring and pinion (rear end), or the rack and pinion which is a steering component?

    I am pretty sure you are referring to a ring and pinion so I'll go ahead and answer you question. The R&P gear ratio or rear end gear that you hear people referring to is found by simply dividing the amount of teeth found on the ring gear by the amount of teeth on the pinion gear. The pinion gear is attached to your drive shaft (see a diagram of a rear end if needed). If a truck has a rear end ratio of 4.10, the drive shaft must spin 4.1 times in order to complete a full revolution of the axle/wheel. For example, a 4.10 rear end ratio will provide a mechanical advantage over a 3.73 rear end.

    The final drive ratio which takes into consideration the transmission gearing (dependent on which gear the transmission is in) and rear axle gearing can be found like this.. transmission ratio X RP ratio = final drive ratio. so if you are running in fourth gear on the second gen five speed transmission the trans ratio will be 1:1. If your rear end ratio is 4.10:1 you get a final drive ratio of 4.10:1. 1X4.1=4.1. If you put the transmission into fifth gear, you will end up "over driving" the engine thus resulting in a lower final drive ratio. If you put the trans into third gear you will create an under-driven situation.

    Most people will change there rear end gears for a higher ratio setup in order to create a mechanical advantage when adding larger tires. The benifit to this is more power, but you will also turn more rpm at the same speed resulting in less gas milage and a final top speed which is less than before.

    hope that helps some.

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