Can' find a truck.

Discussion in 'Ask An Owner Operator' started by Kevw45, Aug 24, 2019.

  1. Kevw45

    Kevw45 Light Load Member

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    I can't find a truck with the rear end specs I want for fuel mileage... There are plenty of trucks with 3.55 or 3.7 rear ends, what fuel mileage loss will I get vs 2.67? Can I still get at least 6.5mpg on flat highway terrain, with loads up to 40k lbs?
     
    Last edited: Aug 24, 2019
  2. Dino soar

    Dino soar Road Train Member

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    I don't know that that 267 gearing or 2.3 gearing is all that it's cracked up to be. Here's why.

    The way I understand it the idea is that you have a direct-drive transmission rather than an overdrive so the truck is geared so much higher that you don't need an Overdrive. Apparently overdrive itself creates some type of condition that has a small effect on fuel economy or so they say.

    To me I just think it's the flavor of the day. That's just what they do. Maybe it does give you a small benefit in fuel economy being in direct, it's possible but I think it's something that people debate over. And if I'm wrong I'm sure that someone will be happy to show me hardcore sources that definitively show that's the case.

    You also have to remember that trying to copy what a mega does is not necessarily prudent for a person with one truck. If a mega can save a tiny amount of fuel, something like .005 percent or some tiny ridiculous number, multiplied over 800 trucks that's significant. For one truck not so much.

    I think the main thing is your gearing so that whatever highway speed that you want to travel at your engine is turning at the optimal RPM for that particular engine.

    And don't forget that the higher that your truck is geared (lower numerically), the less power you will have for pulling Hills. That means that if your truck is geared higher it will tend to feel like it's more dead.

    And maybe somebody can explain this to me because I never can really understand this. The trucks with those crazy super high gearing like that do not have super low low gear or super-low low reverse from what I understand. If you're traveling across the country constantly and you only back into a dock once however many days I suppose you can get away with that. But the higher your truck is geared the harder it's got to be to backup without slipping your clutch and if you pull out on a steep hill you're geared so high that's got to be like being a few gears ahead in a different truck. Being geared lower would have to extend the life of your clutch and Driveline.

    Myself, I prefer a truck that's geared low enough that it feels like it has plenty of power, when I pull out in low low gear or I back into a dock in reverse I can crawl pretty well and let my clutch completely out, yet when I am out on the highway I have OverDrive and I can run at the right rpms.

    Something to think about.
     
  3. starmac

    starmac Road Train Member

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    This an older truck, but I used to get 7 pretty easy at 80,000 pulling a dry van at 70 mph between NM and all points in the south east.
    Specs were 12/7 series 60, 13spd, 370 rears, 22.5 lowpro tires. The tires were directional steer all the way around on the truck.

    I quit pulling a van and removed the fairing, went to tall 22.5s, and would do 7 with a flat better sometimes with a lo profile load, but the few times I hooked to a van again, I was at 6 and even below in any bad wind.
     
  4. uncleal13

    uncleal13 Road Train Member

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    Recently I went through LetsTruck fuel gauges looking for what ever combinations seem to do the best for fuel economy.
    ( As an aside, it you are reading this and have your truck on Fuel Gauges, please make sure to completely fill out the specifications of your truck. Very frustrating when guys put in axle ratio of 'Yes it has an axle" and 'Yes it has a transmission'. )
    What I found is that there really is no secret combination. You can find guys with modern gearing doing great, and then the next ten guys with the same setup do horrible. Are they driving way faster? Are they idling the engine all week long?
    Then you'll find guys with 3.70 or 3.55, heck even 4.10's with 11R24.5 tires and getting over 8 mpg.
    But I would suspect they maybe driving closer to 55 or 60 mph.
    So as a compromise: either be patient and find the truck with the specs you really want, grab a truck you find in decent shape and adjust your driving to suite it's gearing, or grab a truck you find in decent shape and have the rear end gearing changed out. Ten years ago I had a truck switched from 3.58 to 4.11 for $5,000.
     
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  5. Wespipes

    Wespipes Light Load Member

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    I'm having trouble finding a truck too. With how bad rates everyones says Itd seem thered be a ton to choose from.

    Been looking for about a month now. Not looking too good
     
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  6. LondRanger

    LondRanger Heavy Load Member

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  7. Deere hunter

    Deere hunter Light Load Member

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    Best set up I ever put together was a 13 double over with 390s you’ll have to find somebody that knows how to build your transmission but oh my gosh it was awesome !!!
     
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  8. Cat sdp

    Cat sdp . .

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    Check any of the the mega carrier’s web sites .... they are always dumping trucks and love those 2.xx axles......

    I wouldn’t touch one..... but that’s just me.
     
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  9. Kevw45

    Kevw45 Light Load Member

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    Schneider seems to be the only mega that has a used truck website... I was kinda interested in one of their trucks, but apparently they don't keep service records, and they wont let me take the truck to a shop...
     
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  10. Cat sdp

    Cat sdp . .

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    https://www.primeinc.com/pedigree/equipment-inventory/
     
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