Looking at engine specs and transmission for fuel efficiency

Discussion in 'Ask An Owner Operator' started by Cdubb, Dec 28, 2021.

  1. blairandgretchen

    blairandgretchen Road Train Member

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  3. Cdubb

    Cdubb Light Load Member

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    That has crossed my mind too, it is 26 years old like you said. The rear rear center section still say 3.91 on the case as the build sheet said but I suppose I could have a different ring and pinion in there and no one changed or removed the tag. I know the trans is an 8LL but I’ll have to verify which one it is.
     
  4. singlescrewshaker

    singlescrewshaker Road Train Member

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    You are right, all the 8LL's RT, RTX, RTO i see are 1:1 or 1:.74 final..

    Almost seems like 4.33 in the rear, or maybe the tach or speedo is off.?

    Have you gps verified the speed at given rpm.?
     
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  5. Cdubb

    Cdubb Light Load Member

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    Glad to hear that little engine is treating you well! I got some hazing going on on take off but she clears up at speed and idle. I’ll be plated for 90k gross to haul grain but I’m in the flat lands and my trips will be under 100 miles out (usually less than 50). I think it will be ok just wanted to try and give myself the best chance to get the best mileage I can of course.
     
  6. Cdubb

    Cdubb Light Load Member

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    Yes had actually two gps sources going during the test and they read identical speeds. The trucks Speedo is not working right now. One more thing to iron out before go time. I suppose tach could be wrong too but it sure sounded like 17-1800 rpm lol

    Spec sheet trans is a RTX14708LL
     
  7. Brettj3876

    Brettj3876 Road Train Member

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    Can count on 1 hand in the last 6 months we've been over 15,000 Lol.......and light usually pays better too

    [​IMG]

    My normal load
     
  8. Cdubb

    Cdubb Light Load Member

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    Ok I have a theory of what’s going on but I need to hear from someone with experience on the 8LL. My splitter on the side of the shifter is stuck, from the videos I’ve watched what would be low in a 13 speed is actually high on a 8LL. So my understanding is pulled back is high, forward is low mine is stuck back. I guess my new question is can you use that low low split in every gear? And what is the ratio in low low? Can’t seem to see drive rations for that low split.
    Would definitely make sense that if its split into low range my rpms would be way up. Ran a 15 speed today and had her in high gear but split into low, rpms were similar at 60. Was gonna fix that but wasn’t very high priority since I don’t think I’ll need low low maybe ever.
     
    Last edited: Dec 30, 2021
  9. haycarter

    haycarter Road Train Member

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    Those 3176B's are a Great Little Motor..
    I had one back in the Day. Though Mine was set @ 365Hp & I had an 18speed.
    Definitely one of the Better Trucks I've owned over the years..

    IMG (7).jpg
     
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  10. Cdubb

    Cdubb Light Load Member

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    Good looking rig! Also glad to hear you are a fan of the b models too. I know most CAT guys I talked to haven’t spoken highly of them but say the b models were far superior to the a models.

    Since you had some wheeltime with one let me ask you this, we’re you able to smoothly float the gears downshifting? I haven’t had much seat time in mine so maybe that’s what I’m feeling but it’s a little rough getting it out of gear at the shift point. Read elsewhere a lot of guys will double clutch downshifting on them. Did you do that?
     
  11. haycarter

    haycarter Road Train Member

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    It's at least 22-3 yrs since I sold that Truck.! But from (foggy) Memory "Yes"

    CAT ECM's have (or at least did) a feature called Latch Control which meant that the Jacobs Brake would Work when you had your foot on the Brake pedal.. Lift your Foot NO Jake.
    This Feature makes it VERY easy to Float Downshifts... I still use the Clutch on Compound Shift though.. As It's a bit easier on the range change Syncro..
     
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