Axle bushings

Discussion in 'Volvo Forum' started by Metalicious, Jan 18, 2023.

  1. Metalicious

    Metalicious Road Train Member

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    What would symptoms of worn bushings be in a volvo 780? I'm assuming these are actually the suspension bushings rather than axle, they are in the leaf springs on the drive axles. Anyway when I loose my air at night the truck I guess moves a couple inches when the bags lose their air. The front drive axle bags look rolled forward when no air in them. Will move a trailer about 3 inches from dock stops if air runs out of bags then too. Would this cause the truck to feel like its jetking when driving or maybe make ubolts on axle shift around?
     
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  3. Kshaw0960

    Kshaw0960 Road Train Member

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    What you describe is normal. When the air is depleted and the bags deflate, your truck doesn’t lower in a perfectly straight up and down line. Think of it more like a triangle (I’m being grossly over exaggerated to explain the point) where one of the 3 sides is your air bags. As it deflates your truck lowers at an angle which causes the truck to move a bit.

    Think if it like the airbags on the back of your sleeper. When they deflate your sleeper moves back while the pivot is in the front. The entire sleeper doesn’t lower, just the back.

    Signs of bad bushings are tire shoulder wears in steers, irregular tire wear, lose alignment rapidly, and if really bad can hear almost like a pop as it moves on the front axle during hard slow speed turns.

    It also depends on the suspension. I remember stoughton trailers would move like 6” from the dock and I was always frustrated. Wabash actually has 2 arms that come down and keep the trailer from creeping or lowering to prevent this. Other suspensions and trailer manufacturers have their own designs (most use the same couple types of suspension such as Hendrickson).
     
    Last edited: Jan 18, 2023
  4. Metalicious

    Metalicious Road Train Member

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    Well gosh dang idk what the deal is with my truck then. Thank you for the answer though. I'll just have to try to figure out the air leaks. It's annoying to me still even if it isn't the cause of anything else. Alignment when I got one done last week guy said one axle was hard to align probably cause of bushing. Just got me to thinking maybe thats my issue with it feeling like it's jerking sometimes going down the road.
     
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  5. xsetra

    xsetra Road Train Member

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    U bolts should not move. If they move and you might see a rust trail or a shiny spot. Replace Ubolts.

    I believe either of these worn parts would be reflected in odd tire wear. (mentioned earlier)

    Not sure what would give you the jerking feeling going down the road.
    Let us know when you find out.
    Good luck.
     
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  6. Metalicious

    Metalicious Road Train Member

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    Ubolts got replaced before the alignment. The shop noticed they'd shifted some. Not sure how or why though. They were riveted on so shop had to cut them off and replace with ubolts and nuts.

    I'll keep looking into the jerking. It isn't all the time, kind of hard to explain could be steers maybe or something off center. I'll let you all know when I figure it out though.
     
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  7. xsetra

    xsetra Road Train Member

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    When I had my Ubolts replaced, I retorqued them after a couple weeks. Same with motor mounts and spring hanger bolts.
     
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  8. Metalicious

    Metalicious Road Train Member

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    I'll have to do that, if I can find sockets big enough. I have a shade tree mechanics tool set with me, and that's all. Come to think of it though it did feel a lot better after they did all that then not as good feeling. So might have come lose again already.
     
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  9. Kshaw0960

    Kshaw0960 Road Train Member

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    A jerking motion is definitely something like a loose u bolt or loose or cracked leaf spring hangar. I just did the bushings on my truck and the front leaf spring hanger where the bolt goes through was oval shape from bad wear when the bolt loosened up and I never caught it. Perhaps a really bad kingpin as well. Maybe a cracked leaf spring. Who knows, just inspect and retorque everything.
     
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  10. Metalicious

    Metalicious Road Train Member

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    The guy that I bought the truck from had new front leaf springs put on, but I don't think they changed the shocks. He had that done at Bruckners in Ft. Worth. But he was one of those "if its not safety related I don't worry about it" types. He was honestly a #######. Idled the truck for no telling how long because he was so stupid he didn't realize all he had to do was wiggle a dang fuse to get the apu to work. But thats all another story. I need to go get the clutch or transmission calibrated, I know because the kickdown on the accelerator pedal doesn't work. It should downshift on its own pushed to the floor and it doesn't. Unless the sensor is bad, and the pots inside the throttle pedal sensor are fighting each other. I did at one time swear I had a bad injector but it starts too easily for it to be that.
     
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  11. Metalicious

    Metalicious Road Train Member

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    A lot of my issues with the uncomfortable ride and really bad jerking was believe it or not the freakin cab bushings. They replaced those and it rides a hell of a lot better. The cab use to bottom out, a lot driving down the road. Especially on that rough spot on 30 heading east toward Little Rock. Now I know I need new cab shocks even, and it still doesn't bottom out with the new cab bushings being put in. Other than these nuance issues I am having to chase down its not a bad truck. Definitely wouldn't have paid what I did for it though had I either a.) gotten to pull even an empty trailer behind it when I test drove it, or b.) was given the opportunity to have it thoroughly looked over by a well qualified mechanic, not a mecca-nic like he was taking it to for all his work to be done. He got screwed on a lot of things with that mobile repair service guy he was using.
     
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