264 Rear Axle Ratio???

Discussion in 'Trucks [ Eighteen Wheelers ]' started by whoopNride, Jan 26, 2013.

  1. Red Rocket 1964

    Red Rocket 1964 Light Load Member

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    The efficiency of direct drive trans comes from the direct linking of the input and output shafts in high gear. Effectively taking no energy in the process. An overdrive trans requires energy to multiply the output shaft RPMS.
     
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  3. Cowpie1

    Cowpie1 Road Train Member

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    Yes, I do use a 18 spd with 2.64. I am usually in 16th (direct) at my normal cruising speeds. It would be hard to tell some of the other trucks around me on the road that using 2.64 rears is real lousy on hills. Just yesterday, I had 46,140 in the box and was running the rolling hills on I-80 in western Iowa. I had no problem actually gaining on trucks going up the hills that had passed me going down the previous hill. I was more than able to actually maintain road speed within just a few mph whereas one heck of a lot of trucks around me were losing substantially more speed than me on each hill. We were all bucking 20-30 mph crosswinds. I would seriously doubt they were loaded much heavier than me.

    It all can work quite effectively in the right hands when the truck is spec'd properly overall. Some of this has a lot to do with where the sweet spot range is on the engine you have. It works quite well with an engine that seems to do it's best work in the 1350 to 1550 rpm range. There is also something like using 2.79 or even 2.47 for other engine applications. This assumes low pro 22.5 rubber. One could get a different result using taller rubber. I will concede, it is not the ideal for city p&l work. But it is only a detriment if you are the type that likes to use the traffic lights as your own Christmas tree lights as if you were at a NHRA event. Tall ratios like 2.64 are not ideal for jackrabbit, racing light to light, type of driving.
     
    misterG, Trkr 4 Lyfe, Jim837 and 2 others Thank this.
  4. bubbanbrenda

    bubbanbrenda Road Train Member

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    10/4.... the guys that want to put it in the big hole, set the cruise, and hold the steering wheel, aren't going to like the tall gears.
     
  5. SHO-TYME

    SHO-TYME Road Train Member

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    If they were paying for the fuel they would.

    Bruce from Pittsburg Power has done alot of work with building a glider with this 2.64/18 speed setup, it makes alot of sense.
     
  6. sdaniel

    sdaniel Road Train Member

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    Walmart, USA, snd, and maverick have been using that set up for years. A 13 or 18 works little better, with it. If it can work in flatbed...
     
  7. 25(2)+2

    25(2)+2 Trucker Forum STAFF Staff Member

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    the road less travelled
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    The new Cascadia Evolution has a 12 speed direct automated coupled to a ratio of around 2.50, Mack is coupling the M-drive overdrive to a 2.64 if I remember correctly and that is available now.
     
  8. allan5oh

    allan5oh Road Train Member

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    This gearing with a 10 speed direct is equivalent to a 10 speed overdrive with 3.55's. Each gear matches up to less than 1% difference. So there's no huge issue with startability.
     
  9. Army91W

    Army91W Heavy Load Member

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    Thanks to the original poster. I like to come on here and learn something. It's nice there is something to read instead of 27 different threads asking about orientation for xyz company every single day. lol
     
  10. Cowpie1

    Cowpie1 Road Train Member

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    Dead on right. It is virtually identical. 2.64's with a direct 10 will give the same road speed as 3.55 and a 10 OD. The only problem with a direct 10, is that they are not built to handle high torque ratings. They have a great low end that even exceeds the low on a 13 or 18 by a hair. That was the primary reason I went with an 18. I effectively have 16 gears over the range that a direct 10 would cover, and will handle much more torque. Some of the newer 12 speed direct type of trannies are being built to handle greater torque.
     
  11. JarradS

    JarradS Light Load Member

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    Bingo. Volvo I-shift Direct can handle 1920ft/lb

    Mercedes g281 12spd direct - 2050ft/lb
     
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