3:42 rears

Discussion in 'Heavy Haul Trucking Forum' started by Hotshot2trucker, Aug 9, 2020.

  1. Hotshot2trucker

    Hotshot2trucker Bobtail Member

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    I have a 2013 Pete 388, 70" standup sleeper with 268" WB . It has 550 hp, 1850 torque , 18 speed Eaton with 3.42 rears . Truck is dbl framed back half of truck , holland fw35 5th wheel, air trac suspension , 46k drives on 11R24.5 rubber . It has a Muncie dual line wet kit, with a rgn jack plate on rear of frame for detaching hydraulic neck . Do yall think the 3.42 rears will pull a 6 or 8 % grade . Or should I swap for 3.90 rears .
    I would like to pull the load not creep down the road
     
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  3. beastr123

    beastr123 Road Train Member

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    This is just my opinion.
    You should be ok for 6 axle loads as you are as long as you stay close to pavement.
    I would not try much over 105k with those gears in dirt or over 7% grades as you will find the weakest link in your drivetrain sooner than later.
     
  4. Hotshot2trucker

    Hotshot2trucker Bobtail Member

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    So , should I change my gears to 3.90 gears
     
  5. bad-luck

    bad-luck Road Train Member

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    3.90 would be better for pulling hills. It all depends on where exactly you are running. You're going to gain RPMS at highway speed which will lower your MPG. What are your RPMS now at 65 or 70 mph?
     
    Last edited: Aug 9, 2020
  6. AModelCat

    AModelCat Road Train Member

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    Lower gears likely won't get you up the hill any faster. Instead of dropping 2 gears to make it up a hill with 3.90s you might have to drop 3 to get the same torque to the ground with 3.42s. Lower ratio in the rears primarily helps get things rolling easier.
     
    Last edited: Aug 9, 2020
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  7. Hotshot2trucker

    Hotshot2trucker Bobtail Member

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    Around 1500
     
  8. Hotshot2trucker

    Hotshot2trucker Bobtail Member

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    My other truck is a 2013 Volvo 630 mid roof sleeper . 500 hp , 1750 torque 3.55 rears and 13 speed Eaton with Volvo d13 . I've pulled cat gens and gross 107k and it pulls fairly well, so I would think isx 15 550 hp 1850 torque would pull better but pete has the 3.42 gears .I'm not worried in losing mph cause the pete will do 90 and 65 mph is fast enough with oversized loads but going up grades would like to be able to maintain at least 40mph . Most of our loads are heavy equipment like 326 excavator, 336 excavator but would need a jo jeep and a fee link belts that are around 105k weight just the machine. So I would like to see what I would need to change to not drop 3 gears or more.
     
  9. bad-luck

    bad-luck Road Train Member

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    I would guess you'd be 1650 to 1700 with 3.90's But if you're hauling heavy loads I would imagine your fuel mileage is around 5 anyway, so that may not matter to you. I have a 2000 Pete with a 3406E it is set to 525. I have an 18 speed with 3.55's I am about 1350 at 66 mph
     
  10. AModelCat

    AModelCat Road Train Member

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    If you want to go up the hill faster, make more power.
     
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  11. Cat sdp

    Cat sdp . .

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    I’d put 22.5 rubber on it before changing the rear gears....
     
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