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Clunk from rear going over even bumps

Discussion in 'Ford Raptor Suspension Discussion and Modification' started by allinon72, Jan 3, 2020.

Fox - Redefining Ride Dynamics
  1. allinon72

    allinon72 Full Access Member

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    I'm getting a clunk/wallow from the rear end going over bumps that effect both rear tires, like a raised expansion joint. Obviously this also unsettles the truck but I believe that's normal. Trying to figure out how to mitigate it at least - I've narrowed it down to the leaf spring eyelet bushings. My shocks are brand new OEM. Has anyone experienced this and what was the fix?
     
  2. B E N

    B E N Full Access Member

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    Your talking about hitting an expansion joint at speed in a curve unsettling the rear? If so yes that's normal for a live axle setup. The tires temporarily loose full contact. There aren't any really simple/cheap fixes for this. If your bushings are worn it could do nothing but help if you fix them, what do you run your tire pressures at? What size tire?
     
  3. allinon72

    allinon72 Full Access Member

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    I'm talking straight at moderate speed, say 40mph. I run stock tires at stock tire pressures.
     
  4. tltoronto

    tltoronto Full Access Member

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    On your drvers side all the way back by your bumper, the frame has a harmonic balancer weight. Jam a rag in it and go for a drive. See if its the culprit. I have been toying with removing mine since I wonder what it does and the bushings look a little shot. Plus the thing probably weighs the same as a corolla so that would be nice to pull off.
     
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  5. DezertRaptor

    DezertRaptor Full Access Member

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    Ive been noticing something similar i think, everytime i drive over a speed bump it seems like theres play somewhere in the rear, like if the bed was loose

    rear shocks are brand new
    I press down by the rear bumper and can hear a knock coming underneath the bed

    havent checked leaf/shackle bushings
     
  6. MTF

    MTF FRF Addict

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    It's probably that massive block of steel (vibration dampener) between the bed and frame rail on the drivers side rear.
     
  7. DezertRaptor

    DezertRaptor Full Access Member

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    Any pics of what youre talking about?
     
  8. TipsEZ

    TipsEZ Member

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    Following along as a newer GEN1 owner. Lots to learn after a couple decades of Jeeps.
     
  9. trayack

    trayack Full Access Member

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    I'm actually dealing with something similar but its not audible. ( I posted about this on the Ford Raptor Owner's Group on FB )

    For me I'm getting the vibration from the ass end that feels like the first inch of bump travel isn't being dampened by the shocks. If you think of a sign wave, I'd say its about 4-5 waves before it settles out after the bump. I'm the original owner and I can positively state that the truck has not done this for its entire life.

    As of now the truck (2013 SCab) has 52K miles on it. The factory shocks were replaced roughly 1000 miles ago all the way around and that changed nothing. I just replaced the leaf springs with the ICON springs 100 miles or so ago and that too has not changed the feeling. When I did the springs everything was torqued to spec with while the truck was under its own weight. I reused the factory shackles and checked to ensure they were in good order before reinstallation.

    Spare tire is tight up to the frame, and the left frame rail weight is in tact. In the past I've ziptied the weight into a fixed position and this had no effect. I'll give that a shot again I guess to be sure.

    Yesterday I did a few dump runs with roughly 150lbs or more of brush/tree material in the bed and that DID help a fair amount I will say.

    - Travis
     
  10. B E N

    B E N Full Access Member

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    Have you checked your cab and bed mounts, suspension bushings (all the rubber stuff that keeps the truck from being noisy)? Did you get new or rebuilt shocks? If you got your shocks rebuilt I wonder if the bores are worn at the center of travel, get out of that range and your back in good working territory
     

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