Heavy front bumper shaking?
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Cargo Master
Joined: Nov 2006
Posts: 2,171
Likes: 20
From: Denton, TX
Heavy front bumper shaking?
Has anyone noticed their heavy front bumper shaking?
Mine is a ranch hand that I can only see the top of if I sit up a little to peek over the hood. Most of the time I never see it.
Noticed the other day as the truck rumbles across bumps that the bumper shakes too.
Yes, the bolts are tight.
Mine is a ranch hand that I can only see the top of if I sit up a little to peek over the hood. Most of the time I never see it.
Noticed the other day as the truck rumbles across bumps that the bumper shakes too.
Yes, the bolts are tight.
Cargo Master
Joined: Nov 2013
Posts: 2,168
Likes: 3
From: South Central,MO
Every heavy bumper we have and all the ones we have ever had shake. They way they are mounted to the frame and the way they stick out gives them the shakes. You don't notice the natural shaking of the truck because your cab is isolated with mounts to keep you from feeling it. The brush guard on my 89 (in my pic) is mounted to the OEM bumper and reinforced with extra brackets that go to the frame and it shakes just like the others. Just keep an eye on the bolts so they don't get loose and eat out the holes and the bumper will do fine. One other note; use good heavy flat washers, preferably grade #8, and #8 bolts and tighten the crap out of them. DO NOT use lock washers! They will crack and fall out under the shaking stress and then everything gets real loose real fast. If you have problems after that, the next step is fine thread #8 bolts. Lock nuts aren't a bad option either.
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Cargo Master
Joined: Nov 2006
Posts: 2,171
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From: Denton, TX
Thanks, good info on split lock washers. I've seen them get spit out.
I am chasing a shake that I do feel. I feel it, though subtle, when the bumper shakes at slow speeds. At 65ish the truck really shakes, and the bumper moves too, but not necessarily more than at slower speed.
I'm thinking the bumper shake is not adding to frame shake. But I'll remove it just to make sure.
And yes, the tires were rotated and balanced twice, then road force balanced, with no change.
I am chasing a shake that I do feel. I feel it, though subtle, when the bumper shakes at slow speeds. At 65ish the truck really shakes, and the bumper moves too, but not necessarily more than at slower speed.
I'm thinking the bumper shake is not adding to frame shake. But I'll remove it just to make sure.
And yes, the tires were rotated and balanced twice, then road force balanced, with no change.
Cargo Master
Joined: Nov 2013
Posts: 2,168
Likes: 3
From: South Central,MO
Correct, but frame shake IS adding to bumper shake. The further forward and up from the frame you get, the more magnified every little shake gets. The movement you see is a normal occurrence when the frame shakes, the frame shaking all the time though is something that needs to be checked out. It probably still has something to do with the wheels and tires. When they balanced them, did the check them for " out-of-round"? I went thru the same thing. I put my truck on a lift and spun each tire. Watching it spin told the story real quick. I had one wheel that for some reason was no longer round. I put my spare on in place of that one-problem solved. Had the tires swapped around from good wheel to bad wheel and now no more issues.
Logistics Pro
Joined: Mar 2011
Posts: 4,197
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From: Central Wisconsin
If the bumper is moving a lot compared to the rest of the front end, you might want to look at your body mounts and the bottom of your core support. Common place to rot out and that would cause the bumper to bounce a lot.
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Cargo Master
Joined: Nov 2006
Posts: 2,171
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From: Denton, TX
The bumper really only shakes, and mostly front to back. Maybe 1/4"…1/8" front, 1/8" back. The core is solid and the bushings replaced with urethane a few year ago. I'll check them again though.
The shaking is at my feet and in the seat. Agreed on the frame shacking is adding to the bumper shake. I think whatever is causing it is moving around much more than the bumper is.
There's a similar thread on the .org board about the '00 and newer long beds having a shake that seems to come from the natural frequency of the frame. Some have stopped it with braces etc.
Though I still think this is being caused from the rear end, and not the front, the tires are certainly still suspect. Discount tire swears they are near perfectly balanced and round. I'm due for another balance, I'll ask to watch.
The shaking is at my feet and in the seat. Agreed on the frame shacking is adding to the bumper shake. I think whatever is causing it is moving around much more than the bumper is.
There's a similar thread on the .org board about the '00 and newer long beds having a shake that seems to come from the natural frequency of the frame. Some have stopped it with braces etc.
Though I still think this is being caused from the rear end, and not the front, the tires are certainly still suspect. Discount tire swears they are near perfectly balanced and round. I'm due for another balance, I'll ask to watch.
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Cargo Master
Joined: Nov 2006
Posts: 2,171
Likes: 20
From: Denton, TX
Your input is very helpful.
I took the bumper off and drive it for a few days and the shaking is still present. The bumper missing didn't significantly change the shaking.
I reinstalled the bumper and used a thick plate under the bolt heads and nuts, spreading the load of the bumper across more of the bumper mounting tabs. This noticeably reduced the amount the bumper moved.
I took the truck back to Discount Tire, showed them camera video of two of the tires seemingly out of round while jacked up and spinning.
They gave me most of my $ I spent on the first set of tires against a better set.
While off, I had them spin each rim. The worst of the 4 rims (there were three of us watching each one) had a barely perceptible wiggle to it. My estimation (they wouldn't let me get close to the spinning rim with my fingers or a tool) is there was .010" run out. In a way I was hoping to find a wobbly rim, but also relieved to see them straight.
With the new tires the shaking at about 65mph is gone.
In case this comes up in a search, I believe this issue is resolved.
I took the bumper off and drive it for a few days and the shaking is still present. The bumper missing didn't significantly change the shaking.
I reinstalled the bumper and used a thick plate under the bolt heads and nuts, spreading the load of the bumper across more of the bumper mounting tabs. This noticeably reduced the amount the bumper moved.
I took the truck back to Discount Tire, showed them camera video of two of the tires seemingly out of round while jacked up and spinning.
They gave me most of my $ I spent on the first set of tires against a better set.
While off, I had them spin each rim. The worst of the 4 rims (there were three of us watching each one) had a barely perceptible wiggle to it. My estimation (they wouldn't let me get close to the spinning rim with my fingers or a tool) is there was .010" run out. In a way I was hoping to find a wobbly rim, but also relieved to see them straight.
With the new tires the shaking at about 65mph is gone.
In case this comes up in a search, I believe this issue is resolved.
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