Mack Truck Transmissions

Discussion in 'Tanker, Bulk and Dump Trucking Forum' started by Dino soar, Jan 31, 2025.

  1. Dino soar

    Dino soar Road Train Member

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    Right now I am looking at a mid-90s Mack RD tri-axle dump truck with an E7 mechanical 350 and an 8ll.

    If I buy this truck I'm just curious how a 13 speed would do, because I have one that is like new.

    As I have done research on Mack Trucks and transmissions and gear ratios, it got me thinking that I wanted to ask a few questions to drivers that have really spent time in these trucks.

    I used to drive these trucks of this era in the mid-90s.

    I drove for one company that had a 6-speed like a T2060 transmission. Mated to the 300 horsepower engine, that combination was good.

    It wasn't fast but it seemed like that truck was designed in such a way for that gearing. Like it all worked together the way it was designed to.

    That's a really good setup for a truck that's a local vocational truck, like say something for a paving contractor.

    Then I've driven the Mack Rd with a 350/ 400 engines, and they had 8ll transmissions.

    I don't remember thinking I needed more gears. I seem to remember the same feeling that the truck was all designed to work together as one and it did it really well.

    Much faster than the 300 and the power was much more even and able to get up to road speed and it just worked better.

    That's set up was 100% great for a tri-axle dump truck that's going to work in a larger area than just the immediate town.

    It had plenty of power to take you up and down Hills and from what I remember the trucks would cruise at 65 or maybe even 70.

    So my question to you guys that have spent a lot of time in these trucks is that is there any advantage to going to a 13 speed or an 18-speed transmission?

    It seems like a tricky question for me because the Mack is just different than everything else. The way that that engine pulls is just like nothing else.

    For example, if you got a little more RPMs out of your engine and you could shift around 1400 or 1500, the Mack would just pull your right from there up, no problem, better than it would at the 1200- 1300 I think you normally fall to.

    Maybe more gears or being able to split them would do something similar?

    So I don't know, does more gears help when you have an engine that pulls like that?

    If you've driven both setups, I'm curious what you think.
     
    Last edited: Jan 31, 2025
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  3. RockinChair

    RockinChair Road Train Member

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    The main difference is that the 13 speed gives you more ratios to choose from on the top side. This is great if you run in a hilly area because you have more gear ratios to keep the engine where you needed in the power band, or if you're particular about keeping your engine in the sweet spot for fuel economy purposes.

    The only advantage of the 8LL is the granny gear can help you get rolling if your engine doesn't make much torque and/or if the drive axles have high gears.

    I will list all the ratios below, from the lowest to the top gear, in case you want to fire up your calculator.
    8LL:
    14.56 (LL)
    9.42 (L)
    6.24
    4.63
    3.40
    2.53
    1.83
    1.36
    1.00
    0.74

    13 speed:
    12.31 (L)
    8.64
    6.11
    4.43
    3.23
    2.29
    1.95
    1.62
    1.38
    1.17
    1.00
    0.86
    0.73
     
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  4. 201

    201 Road Train Member

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    I drove a Ford dump truck with a BC Cummins and 8LL, and thought it was a worthless POS. Not an expert by any means, but I think the 350 is a different motor than the old "Maxidyne 300s", when a 5 or 6 speed was good enough. I'd have to think, the 350 still has Mack low end grunt and a 10 speed should be all you need.
     
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  5. abyliks

    abyliks Road Train Member

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    Is it a Mack trans or an eaton fuller?
     
  6. FLHT

    FLHT Road Train Member

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    I was of the understanding that Mack is using an Allison trans now.
    I have driven both and the Allison beats the Eaton hands down.
    Plus the Allison can be fixed.
     
  7. Dino soar

    Dino soar Road Train Member

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    I would guess that the big Cam that you drove was probably 300 horsepower or something babyish like that.

    If you drove a 400 that the right person tuned it, that would probably be your favorite truck, it would be so much fun to drive.

    The Mack Trucks of the late '90s era, I drove them with an 8 ll. They did well with that transmission.

    That Mack 350/ 400 engine is really awesome the way it pulls.

    But that must be a crazy cool feeling how that pulls with the 18-speed.

    I can't wait to try it.
     
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  8. RockinChair

    RockinChair Road Train Member

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    The ones I posted were from Eaton Fuller. If OP can give me model numbers for the Mack transmissions then I can try to find the gear ratios for those, too.
     
  9. Dino soar

    Dino soar Road Train Member

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    The only numbers that I have is T2130 is the Mack 13 speed transmission.

    I keep hearing about a mack 12 speed but I guess that's a different transmission.

    Mack Trucks really made a lot of different kinds of Transmissions over the years.
     
  10. Dave1837

    Dave1837 Road Train Member

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    I drive 2 Mack tri axles part time, one is a Granite CV with a 427 and a Mack 10 speed with the multi reverse, the other is a Granite GU with a 485 and an Eaton 18 speed. I rarely split the gears in the 18 speed because the engine will pull down to around 1,150 rpms. Though pulling out of the dump on an off road 15% grade it is nice to flip that splitter when needed
     
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  11. 201

    201 Road Train Member

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    Bingo, not even, a 290, I think. For a dump truck application, I didn't care for it. I drove those air over and under Mack 10 speeds, I thought were worthless too. 13s were created for the old "needle against the pin" Detroits, and I have to say, the best all-around transmission,,,for me, was the 10 speed RoadRanger Dave Dudley sang about. It worked with a wide range of motors and without question, the most popular transmission I ever drove.
     
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