back to 68mph

Discussion in 'R&L Carriers' started by puertorro, Feb 4, 2009.

  1. Demolitionman

    Demolitionman Super Moderator Staff Member

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    None of the companies that have messed with the speed of their trucks have taken into account the rear end ratio along with the final ratio of the transmission. Depending on how they ordered them, you guys very well could have gotten great milage at 75 vs. 65 b/c at 65 the trucks were bogging down into the lower rpm. I'm curious about it myself.....if someone could give me the rpm you run at 65 or 68 and the transmission model #, I could tell you the rear end ratio.
     
  2. happyhooker

    happyhooker Member

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    Our trucks are speced to run 68mph.... That is taking into account the rear end and transmission. You also have to consider the engine type, and what rpm they get the best fuel economy at, or "sweet spot"....
     
  3. Demolitionman

    Demolitionman Super Moderator Staff Member

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    very true, I did not think of that.
     
  4. leftlanecruiser

    leftlanecruiser Member

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  5. Demolitionman

    Demolitionman Super Moderator Staff Member

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    with a 10 speed direct that would give about a 2.60 - 2.70 rear end ratio, assuming you are running 22.5" rims. If it is a direct 10 speed, you guys should have seen better numbers at 65 vs 68+ .
     
  6. happyhooker

    happyhooker Member

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    They are not direct drive units.... The typical config is 3.73 rear with .74 overdrive ten speed. Like I said before, it all depends on the engine, what type of loads you typically pull, where you run, and how you drive it..... Direct drive is an old school way of thinking, and back in the day with older engines, you would see better numbers, compared to overdrive transmissions. Today, alot of things have changed with the engines.
     
  7. tater gater

    tater gater Member

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    the run that i have has virtually 0 pulls the few that i do have tho are very moderate but our shop forman said that zero rail pressure was added when trks were turned back
     
  8. happyhooker

    happyhooker Member

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    Rail pressure

    If your shop foreman knew what he was talking about, he would know that the rails disapeared in about 1994. Everything is controlled by the computer now, and everything adjusts automatically, according to how the truck needs to run. When the shop turns a truck up or down, they are only changing the speed at which the truck stop sending fuel to the motor.:duh:
     
  9. mechanix

    mechanix Member

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    The problems lies in spec'ing the trucks,,, period.
    R&L has run the same trans to rear ratio for over 15 years that I know of. "running the same transmission and rears in the trucks means less parts to keep on hand". This was stated in 1999 by the fleet manager( still there today), during a conference call discussing the poor pulling ability of the Macks in the mountains of the east.
    Back then most of the fleet was 3xxx-4xxx fords with detroits,it worked and they still out do most other trucks,,, but the engine technology and rpms (torque and power ranges) have all changed,,,, and yet again some things never change.....:duh:
     
  10. happyhooker

    happyhooker Member

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    That is where you are wrong..... They changed the transmission in 99 and the rear configuration in late 2000 (8 years ago) and went from 3.90 and 3.91 rears to 3.73 rears. That is when the engines started changing the way they run. In 2008 they changed this again to another rear ratio to meet the demands for the new emmision engines. I don't want to sound like I am always defending what they have done, but every time you purchase a new truck, you rethink the specs and make sure it works with the engines of that year...... Just giving the correct information... :beerchug:
     
  11. mechanix

    mechanix Member

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    You may be right,as my memory ain't was it used to be...
    But the Macks are still not spec'd correctly, the rpm's are too low in top gear against the road speed limiter. And i know some say it is ok, because the book says that came with the truck. Pure B.S. as with any OEM book,it states lower to cover their butts and make the EPA happy. Actual dyno tests reveal the truths about the trucks,,, or buy a few with varying specs',the mileage and power would show vast changes. and i know not all trucks run the same areas and drivers DO make a difference,,but an additional 6-10 grand per truck would pay bigger dividends at the fuel tanks over a long period of time.
    Last year I couldn't believe R&L was still running 350/380 hp trucks across I-80 and I-81 in Pa. Most companies i dealt with ran a 400 minimum (straight no combo hp) and a few went to all 427's for the fuel mileage gains.



    Don't believe everything you hear,,, and only half of what you see.....
     
  12. mechanix

    mechanix Member

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    Maybe they'll go with the Volvo motors next go around,,,been hearing MOSTLY good things....

    And may be Cummins could be an option.....

    Or that hot new volvo cabover ,,, for tight city work....

    Possibly that ugly Lonestar IH for linehaul,,,, wonder how that would look in R&L green...

    Did i leave anything out???? :biglaugh: :biglaugh:
     
  13. Demolitionman

    Demolitionman Super Moderator Staff Member

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    They put the Volvo 12.7 in our tractors here at Saia. 430HP mated with a 10 speed direct and 2.60 rear gear. At 1500 and 65mph, we get from 6.0-6.3mpg. One truck on the yard runs 68mph, and gets 6.4 at 1550-1600 rpm. I saw the post about the Volvo engine, so I just thought I would give you guys some numbers on how they are doing for us.
     
  14. happyhooker

    happyhooker Member

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    They are actually 330/350 in all of the Mack's.... They are designed to run 1550 at 68mph, and that is where they get the best fuel economy. If you look at a trip report on a Mack, it will show you how often it ran in the "sweet spot", which is that 1550. I am not saying that I agree with the low HP..... They are testing some higher HP engines (so far with good results). They are also testing a newer Mack with the Volvo engine, But IMO the Mack's are not the way to go for many reasons.... The frame rails are not built as heavy as other trucks, they rust out quickly, they have numerous recalls for EGR and other engine problems, they do not update their software to meet the demands of the new engines, and finally the cabs are all steel, which rust out quick! I will say one good thing about them, the truck rides nice.:shrug:
     
  15. mechanix

    mechanix Member

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    One thing that we agree on,,,including Mack/Volvo,,, They MUST get away from the current Renault designed motor to survive. It was actually a good motor in the original design (pre-1999),but suffered greatly with all the egr addons.

    Maybe time to start a new thread.... what would be a good overall truck for R&L??
     
  16. doubles drifter

    doubles drifter Member

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    i like our freightliners. rides real nice handles good and has plenty of room inside, nice truck
     
  17. shadowr434

    shadowr434 Super Moderator Staff Member

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    Where do you work?I wouldnt mind R&L picking up Freightliners for daycabs but that wont happen.
     
  18. Runnin' Late

    Runnin' Late Member

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    We already have them, or do you mean having them @ your terminal?
     
  19. shadowr434

    shadowr434 Super Moderator Staff Member

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    I guess I mean at my terminal because the only Freightliner in our yard is a team truck that never gets used.All Macks and Fords here.
     
  20. leftlanecruiser

    leftlanecruiser Member

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    He was refering to a team truck
     

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