Anyone tow with an '05 2500HD with 3:73 gears? swap my 4:10's to 3:73's? Big diff?

Discussion in 'GM Gas Engine Rigs' started by gmcjimmy88, Jun 9, 2008.

  1. gmcjimmy88

    gmcjimmy88 Well-Known Member

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    My 05 Sierra has 4:10's in it now. It is 2WD so I would only need one set of gears. I am thinking of swapping the gears to 3:73's to get some better MPG's out of the truck. I will never have the max. load on the truck (at least not anytime soon). The RPM's are really high right now with the 4:10's in the truck. How much difference do you think a set of 3:73's would make? Would it really hurt the towing ability? How much should it help with gas mileage? Any help would be great

    The truck specs are as follows;
    2005 GMC Sierra 2500HD Ext. Cab Long Bed 2WD Auto, 6.0 (gasser), 4:10 geared 14 Semi float rear
     
  2. Woods

    Woods Well-Known Member

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    I'd say 1mpg is all your going to gain with the gear swap. Not going to hurt you that much if your not towing heavy.
     
  3. gmcjimmy88

    gmcjimmy88 Well-Known Member

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    I think I have decided it wont help enough to make it worth it.
     
  4. hotrodscott

    hotrodscott Guest

    Similar question here...

    A friend has an '05 with the 8.1L and an Allison...He wants better MPG since the truck is only used for long road trips...He doesn't tow anything heavy at all...Maybe 7,000 lbs. max 2-3 times a year.

    Is swapping to a 3.50 ish ger feasible???

    :popcorn:
     
  5. Seminoles

    Seminoles Member

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    Just my opinion, You know it is funny but all the towing guides before 2005 say the higher the gear (lower number 3.73:1) will tow less then a 4.10:1 but the 2005 doesn't make a difference but 2004 it would be 2000lbs less. For millage and gearing you want the rpm around 2000 rpm or just below the gas engine seams to be the point where lower rpm the fuel drops out of the air (a complete book on that theory) at your average speed you drive the most and size of tires you will be using. Even pulling a heavy load with the 6.0 or (8.1 might run good with a 3.23:1) this will give you about 2000 rpm before you reach peak torque where max efficiency of the engine is which will let you go up the over pass or hill without much problem (of course the grape vine is a different story). :stir:
     

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