Peterbilt 378 roll off axle swap?

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Derek_313, Nov 30, 2023.

  1. Derek_313

    Derek_313 Bobtail Member

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    Nov 30, 2023
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    Good afternoon,
    We’ve got a Pete 378 roll off truck we are considering rebuilding. My question is if anyone has experience switching from rear air ride to spring ride.
    The truck leans to the passenger side normally and any dumpster with a load that isn’t distributed correctly makes it worse. We believe one of the front springs got bent as well which could cause part of it but we are planning to replace those.
    We have some newer spring ride Macks that are much more stable so we’re thinking maybe we should switch to spring.
    Anyone know if that can be done with the same axles or if we need something different? Also any ideas on what springs to go with and where to get them? Any other advice welcome!
    Thanks
     
    W923 Thanks this.
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  3. W923

    W923 Heavy Load Member

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    Yes it can be done with the same axles but you will likely need to grind off the alignment pins on the axles and then either reweld new ones in the right spot or weld the spring seat.
    If your truck only has one leveling valve change it to one for each side….it will make a big difference on the leaning. And if one front spring is bent fix it…which seems like a no brainer. You can probably take both spring packs to a good spring shop and they will arch them to match.
     
  4. Derek_313

    Derek_313 Bobtail Member

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    Nov 30, 2023
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    Ok thanks. Yeah I plan to just replace both spring assemblies in the front. And that’s a good idea on the air issue. I believe it only has one leveling valve so I’ll see about adding another to make them independent. That would be much cheaper than adding springs not to mention much smoother keeping it air ride
     
    W923 Thanks this.
  5. W923

    W923 Heavy Load Member

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    Something I didn’t mention but I assume you know is that the spring ride is going to require drilling at least 30 new holes in the frame and probably several will intersect the holes from the old air ride hangers. It’s totally doable but adds to the time and difficulty
     
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