Forum Discussion

tbchristian3's avatar
tbchristian3
Explorer III
Jan 04, 2024
Solved

Front end bounces horribly when going over 55 mph

Hello everyone,  I have gone through most of the posts for cab over bouncing and I can't seem to find a solution that fits my current set up.  I have a 2015 GMC Sierra 1500 5.3 L V8 4X4 Crew Cab. ...
  • Grit_dog's avatar
    Grit_dog
    Jan 09, 2024

    Not likely the issue at all. 
    I feel like I asked a couple few questions you haven’t answered. As have others. 
    what’s under it for suspension?

    what you got for tires and pressure?

    what kind of road, asphalt or concrete?

    how long how far how many roads and miles have you driven it? Or any other heavily loaded truck?

    I can get an almost empty truck bouncing pretty good at the right speed on the wrong concrete highway. Yet never had even a severely overloaded pickup bounce like that on smooth asphalt. Concrete panels create ridges at each panel joint where they’re saw cut, when the edges swell or curl. Sounds like what you’re experiencing, but until you provide more insight, can’t tell. 

  • mkirsch's avatar
    mkirsch
    Jan 10, 2024

    Concrete panels as in the road surface. Many highways are poured concrete, which have an expansion joint, or a cut line, at regular intervals to control cracking and expansion.

    These regularly-spaced seams in the concrete can set up a harmonic bouncing in your vehicle at certain speeds and/or weights. Asphalt over concrete will do the same thing because the seams are still there under the asphalt.

    Now that you know what to look for you can seek out a smooth paved road that isn't asphalt over concrete, where you can go 55 or faster, to see if it's the truck or the road.

    You don't have to be overweight or dangerously light on the front of the truck to have this problem. You just have to be balanced wrong. Hence why I still think it's a weight transfer issue. In a nutshell: The weight of the 1000lb+ camper sitting at 2-3' behind the axle has lifted just enough weight off the front of the truck to make it sensitive to road seams...

    One other thing that I don't think we've touched on: Is the bouncing uncontrollable or is the truck uncontrollable?