09 Peterbilt 386 front end bouncing between 55-60

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Tama Mai Hawaii Nei, Jan 17, 2021.

  1. Tama Mai Hawaii Nei

    Tama Mai Hawaii Nei Light Load Member

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    Sep 6, 2013
    Las Vegas, NV
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    I have a 09 Peterbilt 386 front end bouncing between 55-60 and has constant slight shake.

    So this one has me stumped. I originally had a bad bounce at 55-60 replaced tires and had them balanced now I have a constant shake like an out of balance tire even had them rebalanced and removed the balance weights and put balance beads in there. The bounce is still there not as noticeable before I couldn't do 55 I had to do 50 or 60 to avoid the bouncing. I thought new tires would solve the problem since the old ones were wearing on second rib and truck sat for awhile on those tires.

    I have replaced leaf spring bushings, all shocks, all 10 tires are new and balanced, cab shocks and airbags replaced, all 6 shocks replaced, new slip yoke, driveshaft removed and balanced, ride height checked and confirmed, 3 axle alignment done, and carrier bearing checked. I also replaced torsion bars in rear and 2 suspension air bags.

    Kin pins are good, ball joints are good, everything has been greased.

    What could I missing I replaced or checked everything that I know of. I don't think rims are bent we balanced them out and the bouncing reduced about 80% once we swapped the tires.

    Before the new tires I did not have a constant wobble. I feel a slight shake in the steering wheel but I mainly feel it in the pedals, shifter and cab, the bounce is definitely coming from the front you can see it in the hood.
     
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  3. Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

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    What brand of tires ? I bought average steer tires a few years ago, Kelly’s to be exact and had the centramtics with them. I noticed right away something was wrong but kept driving. Eventually I removed the centramtics and still had the same problem. So finally I went to a tire shop and he “tried” to balance them on the truck but showed me there was no way, the tires were “out of round”.... so just to let you know, did they balance your tires on a tire balancer or on the truck ? On the balancer, they don’t spin the tire fast enough, on the truck it’s the best way to find out what’s your issue.
     
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  4. Tama Mai Hawaii Nei

    Tama Mai Hawaii Nei Light Load Member

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    Sep 6, 2013
    Las Vegas, NV
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    They're Bridgestone tires. Both times where on the machine TA and Ted Wiens. When the second shop double checked TA balancing they were accurate but I still went ahead and rebalanced them.

    I originally had centramatics but thought maybe they were the issues so had them removed. The tires do balance out with the tire beads in them.

    The thing that throws me off is the 55 mph bounce I have before and after the tires. This makes me lean towards something else as the issue.
     
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  5. baha

    baha Road Train Member

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    Look closely at the rubber line formed in the tire close to rim look at it and space tween it and wheel all the way around the wheel to see if the tire is mounted centered on wheel ? if it is centered on wheel, you can find a shop with a tire grinder that spins tire with it on truck and grinder is put on tire till its round again.
     
    Last edited: Jan 17, 2021
  6. AModelCat

    AModelCat Road Train Member

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  7. Tama Mai Hawaii Nei

    Tama Mai Hawaii Nei Light Load Member

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    Las Vegas, NV
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    You know I never check. I put new brakes up front mechanic said drums looked fine so never paid much attention. I do know there isn't any weights on the drums. My rear drums have a weight on them.
     
  8. Rideandrepair

    Rideandrepair Road Train Member

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    They most likely have a flat spot ground out on outside for balancing, instead of a weight added.
     
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  9. craig_sez

    craig_sez Road Train Member

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    Even though you did the ballence and alignment,chk out and look for company called md align...Seems to me i think i did hear that factory alignment #'s are off a smidge....
    Next time your rollin down the road(bob tail)and its clear a longs ways,go over the center line and notice if the bounce goes away for a second then back...
     
  10. Tama Mai Hawaii Nei

    Tama Mai Hawaii Nei Light Load Member

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    It does go away depending on the road surface it is worse when the road is smooth
     
  11. craig_sez

    craig_sez Road Train Member

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    Yeap my cascadia is the same..Tires were replaced and replaced again,ballanced with beads,alignment and right around 55 it starts and gone by 70ish..I notice it bobtail and a tiny tiny tiny bit with a trailer on..
    When freightliner did an alignment most of it was gone.....Sometimes especially when on cold pavement i dont feel it at all..Hell i can see front end shake up n down now and then in my headlights..
    Company truck so not much i can do..
     
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