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Gear Ratio's

Discussion in '6.7L 3rd Gen Cummins' started by endorphine44, Oct 31, 2006.

  1. endorphine44

    endorphine44 Registered User

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    Ok guy's, forgive me for being slightly ignorant when it comes to mechanical workings and gears. I'm looking at the 07 2500 with a 6 speed auto...Mostly for everyday driving, very little real towing the gears are:
    Gear Ratios
    1st ---- 3.231
    2nd ---- 1.837
    3rd ---- 1.410
    4th ---- 1.0
    5th ---- 0.816
    6th ---- 0.625
    Reverse ---- 4.444
    Overall Top Gear Ratio ---- 2.33 with 3.73 axle ratio; 2.56 with 4.10 axle ratio

    so which axle is going to do better for highway milage? I'm assuming the 3.73, but I'm not quite finding the answer as to why. Can someone enlighten me? Thanks.
     
  2. rebel_horseman

    rebel_horseman Rt. Wing Extremist

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    The 3.73 will give you better mileage. Basically diesels are more effcient at lower RPMs especially when they run unedr 2k RPM. The slower the engine turns the better. The 4.10s are good for towing but only if you are always hooked up and running with a heavy load. Otherwise stick with the 3.73s.

    One other question, if you're not towing why buy a diesel, especially an '07 chassis cab? With the added cost of the motor, the fact that #2 is abotu $0.40 a gallon more, and the cost of maintainence, unless you're towing a lot then a diesel is not cost effective. You said you're not towing hardly at all so why not buy a gasser? Hell that's why I sold my Powerstroke...not towing anything, don't need it.
     
  3. endorphine44

    endorphine44 Registered User

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    Right now I have an F150 single cab, 2WD, 4.2L V6, 5 speed and I get about 18 MPG :mad: . My brother has a 4 door, 4x4, Dodge 2500 Diesel and is getting about 20 MPG. I don't expect gas prices will remain to far off from diesel fuel for very long, and with slightly better milage and the ability to tow what I want if needed, I'd rather have the bigger 4 door, 4x4. I also travel across several states at least once or twice a year and it would be nice to have a truck that can handle the milage and still hold some resale value a few years few years later. I'm looking at late next summer getting a 2500 mega cab, 4x4, SLT...and of course bigger is always better, right? LOL

    Thanks for the info about the gears. ;Sweet
     
  4. beretzs

    beretzs Full Access Member

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    Hey, I would get the diesel just because. Heck, once you get the truck, you can always find something you want to tow. I think it makes great sense to buy a diesel. There isn't hardly a 1/2ton truck out there that will get better mileage, or have the capability of a good diesel truck. Also, asking about gears, stick with 3.73's. Even if you are pulling extremely heavy, the 3.73's are more gentle on the fuel. You can always shift down a gear, and having the 6 speed auto sounds like it will be a nice combo.. Good luck, hope you get the MC. I lke mine alot. Scotty
     
  5. Slaughterhouse

    Slaughterhouse Banned everwhere!!!

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    I am gettig and honest, hand-calculated 18mpg out of my new 6.7L Dodge with 6 speed auto....at 60 mph she seems to be barely running!!!!
     
    Last edited: Jun 18, 2007
  6. Headhunter_5.9

    Headhunter_5.9 there it is Johnny!

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    I would have to say stick w/ the 3.73's as well! due to the fact that it would be nicer fuel economy! basically the 3.73's w/ the 6 speed manual or Auto is very very close to a 5 speed manual w/ 3.55's. as far as the tach goes! in other words @ 70 6 speed 3.73's and 5 speed 3.55's will be taching the same RPM's!

    Slaughterhouse... how many miles do you have on your 6.7? 2x4 or 4x4?
     
  7. Slaughterhouse

    Slaughterhouse Banned everwhere!!!

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    SO far I only have 2100 miles on my 4x4...the book says it gets better with 10000+ miles. Hope I can squeeze 20mpg out of her.


    BTW I have 3.73 gears.
     
  8. Headhunter_5.9

    Headhunter_5.9 there it is Johnny!

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    just took delivery of ours on MONDAY! we are getting 15.3 right now! w/ 600 miles on it!

    more information to come later!
     
  9. Headhunter_5.9

    Headhunter_5.9 there it is Johnny!

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    well we've got 1800+ miles on the '07 now and WOW!!! I'm impressed. before we hooked it to the trailer we were getting an average of 17.4 MPG (hand calculated) only .03 off according to the overhead! once we hooked the trailer to it it fell to 11.0 but that was a full tank of fuel through it. and it's had another tank or 2 run through it w/ the trailer hooked to it on some really nice Illinois highways.... ups downs and curves! nothing flat! and it's still holding out @ about 11 ish w/ the trailer hooked to it!

    can't complain!
     
  10. John Haggerty

    John Haggerty Birth Certificate

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    4.10 Not Needed

    I just bought a 08 CTD with 6 sp. auto and 4.10's. She has so much low end power and with the way the 6 sp. is set up, I don't think the 4.10's are needed. I only got the 4.10's beacuse that's all i could find around with the truck nearest the one i wanted.

    Got to work on my new signature.
     
  11. jaymayisback3

    jaymayisback3 Registered User

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    definetly go with the diesel 3.73. diesel will last longer, get better mileage, and be worth more resale. i cant imagine that there'll be anything you cant tow with the power the cummins makes, get 4.10 if your planning to haul tanks on a flatbed LOL
     

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