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.
264 Rear Axle Ratio???
Discussion in 'Trucks [ Eighteen Wheelers ]' started by whoopNride, Jan 26, 2013.
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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. -
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.
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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. -
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...
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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.
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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.
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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
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Mercedes g281 12spd direct - 2050ft/lb
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