2004 pete 379 low lead level valve flipping

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Liqer1821, Jun 29, 2022.

  1. Liqer1821

    Liqer1821 Bobtail Member

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    Jun 14, 2022
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    Hi I have a 2004 379 with low Leaf, if I take off too hard the leveling valve would flip and dump the air. Replaced the valve 3 weeks ago and hasn't done it until today. Today I was hauling a manure tank equipped with air ride. I ran 10 loads and it flipped 5 or 6 times. Granted we had to pull out onto 65mph hwy. 3 or 4 times for sure empty it flipped when hitting bumps. Front of tank is very light, still we've been told by peterbilt this is how it is. The bottom of the rod was on the pumpkin, we were told to put it on the lower shock mount didn't help, there's no way these left the factory this way. It flipped at 70mph after hitting a bump and I had to just over to the shoulder. Of course the drive shaft sounds like it's going to come through the floor being out of alignment. It may need shocks otherwise, would there be any negative to lifting the rear of frame until just before it flips past center, measure for length and add some limiting straps? My manager just keeps saying that's how it's suppose to he and had always been. Well I fix it and I'm done with dealing with this. Also it does do it with other trailers, such as my all aluminum hopper, again another light trailer on the front my load pressure causing is 30 psi and if I hit a bump it drops to 10 or lower. Hard brake with full Jake's empty pressure has spiked to 50/55 psi making me think the shocks are doing nothing. It did flop loaded before it was replaced but only when I really got on it, more than is ever needed.
     
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  3. Magoo1968

    Magoo1968 Heavy Load Member

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    St Malo mb
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    Shocks and torque rod bushing are probably worn out . Many guys go into the bush with those suspensions something is definitely allowing it to lift to much
     
  4. Liqer1821

    Liqer1821 Bobtail Member

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    Jun 14, 2022
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    Thank you I was told the shocks were replaced a little over a year ago, I will check the bushings
     
  5. High Stepper

    High Stepper Bobtail Member

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    Jun 8, 2022
    Square One
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    If the geometry is off after you adjust the suspension, you run the risk of damaging the transmission. The driveline angle is set to certain specs and may cause damage to the rear box if too far out.
     
  6. Liqer1821

    Liqer1821 Bobtail Member

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    Jun 14, 2022
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    The suspension is low Leaf from factory, I replaced the shocks last night all 6 were shot, I could push them together with 2 fingers on each end and struggle to pull them apart. They were the cheap all trux brand aced with Monroe magnums. Also thr leveling valve is level with the frame, it's suppose to be 6.5° above parallel, however the rod is not long enough. But I have the correct rod length I was told this truck has a car hauler front end in it so it sits lower in the front. But the rear is also very low. I know there is a low low suspension but I'm not sure what the difference between low and low low is. The next thing I'm going to check are part # on everything. I inspected the torque arms, the bushings seem to be ok. But I suppose they could be loose which is allowing the up and down travel too much. Even with the new shocks I'm still getting alot of pressure fluctuation on the gauge.
     
  7. Liqer1821

    Liqer1821 Bobtail Member

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    Jun 14, 2022
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    The suspension geometry should be ok, it's correctly set to 8.5" from axle tube center to bottom of frame.
     
  8. AModelCat

    AModelCat Road Train Member

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    Canuckistan
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    From what I remember, truck shocks are normally easy to compress and hard to extend.
     
  9. Liqer1821

    Liqer1821 Bobtail Member

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    Jun 14, 2022
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    No there suppose to be the opposite, that's why there banded together when you install them.
     
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