Need help diagnosing a new vibration at highway speed

JC123

JC123

TJ Enthusiast
Joined
Aug 13, 2018
Messages
174
Location
Arlington, Virginia
2000 Sahara 4.0L, I6. 159k miles. 30" tires, no lift.
I don't drive it on the highway often but did today and felt a vibration mostly in the gas pedal when I reached 65 mph. I want to say it smoothed out a little when I reached 70 mph but I was hesitant to go faster to test it out.
The vibration isn't present at 60 mph.
Since I re-did the brakes recently, I checked the lug nuts to make sure they weren't loose - they were tight.
What else might cause this that I should check?

thank you.
 
Tire balance, very likely to be the cause and easiest to detect/eliminate.

Out of the blue one of my tires decided to go out of the balance. And that was right after regear and few suspension mods. So i was pulling my hair out for almost 3 weeks while trying to figure it out what went wrong. Eventually took it to the tire shop, and turned out that front tire was causing all that vibrating havoc.
After rebalance from time to time it is still slightly vibes between 55 and 60mph, but outside that zone it is a smooth roll from 1 to 113mph.
 
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I have vibrations in most of my cars so not the best to advise but it usually ends up being a wheel balance issue.

I had rotated my tires on rusty and was driving good then when I worked on my brakes a weight fell off the wheel. She now vibrates. If it is within a 10 mph range I would say tire balance issue.

Mine is smooth till45, shakes till 55 and then smooths back out. I know it's my wheel weights
 
Can you describe the vibrations in more detail?
There are three major causes of vibrations to look at.
  1. Engine vibrations - you will notice an audible vibration at higher engine speeds that changes pitch or frequency as the transmission shifts gears. You would hear it at certain engine RPMs in any gear?, likely even neutral. These could be anywhere in the range of 10-100 Hz depending upon engine speed. At idle, they would be felt and not heard.
  2. Driveline vibrations - you will hear a low pitch vibration at higher speeds that does not change with shifting gears. You will hear it, and maybe feel it, but you won't be able to see the individual oscillations. You may notice your mirrors going blurry. It's generally in the range of 40-80 Hz at freeway speeds. Think of a tone within an octave of a 120VAC fluorescent or motor hum. Sometimes described as a roar.
  3. Tire/wheel vibrations - you will see oscillations at higher road speeds that may have peaks at very particular speeds. You won't be able to hear the vibrations directly because the pitch is below the audible range, but you can see shaking in the vehicle, feel the shaking, and hear things rattle as it shakes. You may notice the mirrors jumping up and down slightly.
 
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Steel City 06 said:
Can you describe the vibrations in more detail?
There are three major causes of vibrations to look at.
  1. Engine vibrations - you will notice an audible vibration at higher engine speeds that changes pitch or frequency as the transmission shifts gears. You would hear it at certain engine RPMs in any gear?, likely even neutral. These could be anywhere in the range of 10-100 Hz depending upon engine speed. At idle, they would be felt and not heard.
  2. Driveline vibrations - you will hear a low pitch vibration at higher speeds that does not change with shifting gears. You will hear it, and maybe feel it, but you won't be able to see the individual oscillations. You may notice your mirrors going blurry. It's generally in the range of 40-80 Hz at freeway speeds. Think of a tone within an octave of a 120VAC fluorescent or motor hum. Sometimes described as a roar.
  3. Tire/wheel vibrations - you will see oscillations at higher road speeds that may have peaks at very particular speeds. You won't be able to hear the vibrations directly because the pitch is below the audible range, but you can see shaking in the vehicle, feel the shaking, and hear things rattle as it shakes. You may notice the mirrors jumping up and down slightly.
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I don’t hear it; only feel it. So makes me suspect #3 is most likely.
 
JC123 said:
I don’t hear it; only feel it. So makes me suspect #3 is most likely.
Click to expand...
I would agree then. Focus on the tire balance, and especially on the lug nut tightening sequence if the wheels (or spacers, if you have them) aren't hub centric.

The Centramatic wheel balancers are very popular on this forum to complement balanced wheels. If you still get a bit of vibration after your re-balance, consider giving them a try
 
It is going to be wheel/tire or driveline .

rotate tires and see if anything changes, if it doesn’t , pull the front driveshaft .
 
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I have a similar "vibration" in an '05 LJ- Automatic- stock- 30" tires- 27 psi- 122k miles. Starting at around 60-65 mph and smoothing out until 70 +/-. It is felt in the gas pedal, steering wheel & seat. Mirrors & phone holder shake. So far, balanced tires (3 times), rotated tires (2 times), 2 alignments, front ball joints replaced, removed rear driveshaft- sent to shop- ujoint replaced- test drove in 4 high without rear driveshaft- test drove without front driveshaft- sacrificed a chicken- installed centrematics balancers- replaced steering stabilizer.
The kicker...New England mornings are now around 40- 50 degrees & afternoons around 70-75. The vibration is worse during the warmer teperatures. Could it be the shocks? It currently has Quadratec Hydro 7.0. I bought the Jeep a few months ago...don'y know how old/new the shocks are.
Sorry for hijackin the thread...
 
Doorman said:
I have a similar "vibration" in an '05 LJ- Automatic- stock- 30" tires- 27 psi- 122k miles. Starting at around 60-65 mph and smoothing out until 70 +/-. It is felt in the gas pedal, steering wheel & seat. Mirrors & phone holder shake. So far, balanced tires (3 times), rotated tires (2 times), 2 alignments, front ball joints replaced, removed rear driveshaft- sent to shop- ujoint replaced- test drove in 4 high without rear driveshaft- test drove without front driveshaft- sacrificed a chicken- installed centrematics balancers- replaced steering stabilizer.
The kicker...New England mornings are now around 40- 50 degrees & afternoons around 70-75. The vibration is worse during the warmer teperatures. Could it be the shocks? It currently has Quadratec Hydro 7.0. I bought the Jeep a few months ago...don'y know how old/new the shocks are.
Sorry for hijackin the thread...
Click to expand...

No.

Have you pulled the front shaft.
 
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AndyG said:
No.

Have you pulled the front shaft.
Click to expand...
X2 to both of those. Also perform a "dry steering test" which will show you if you have worn rod-end joints on the tie rod or drag link or loose/worn bushings elsewhere. With the tires on the ground and engine not running, have a helper do repetitive quick short left-right-left turns with the steering wheel while you sit in front of the steering system and closely watch everything for any any unwanted sideways slop or movement. I was surprised recently when I discovered I had two bad rod-end joints on my drag link which after I replaced them cured a shimmy my TJ developed. There should be absolutely no side-to-side slop or movement at any of the joints where they are joined or bolted together. Know that there is normal and required rotational play about the long axes of the tie rod and drag link because both of those are mounted on ball joints. Make sure the track bar is not moving side-to-side either, it needs to be held firmly in place by its bolts and bushings. There can be the tiniest mount at the passenger-side due to its small rubber bushing there but if it moves it should be barely if at all.

FrontEnd.jpg
 
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I’ve started to have a similar issue, a few months ago I heard popping when turning the wheels of my 01 TJ. Looked underneath and the passenger side sway bar link finally gave out. I went to rough country and bought the sway bar links (replaced both sides) for a 4” lift. I have a 3 “ suspension lift and a 2” body lift running 35s. I read multiple positive reviews from other Jeep owners who have a 3” lift stating the work fine. Shortly after installing the new sway bar links I noticed a vibration when hitting 50mph and up. I looked under the front end and considering the age everything looked good except I could move the sway bar side to side. Then I noticed on the ground next to the front wheel was laying weights that were installed to balance the wheel. Since then I replaced the sway bar bushing, no movement except for up and down. I still have the vibration, I did noticed that because of the length of the sway bar links the sway bar is at 15 degrees tilted up. I plan on getting the tires balanced but could the angle of the sway bar cause vibration, I can feel vibration in the steering wheel, pedals, seat and shifter. It not the death wobble, I know because I have already corrected that. Any help or guidance would be greatly appreciated, should balancing the tires not correct it, what are y’all thoughts?
 
Thanks , I will get them balanced, realistically it will be a few weeks but I will follow up. At this point I’m just trying to get my Jeep back to its normal vibrations, lol.
 
Jod0001 said:
Thanks , I will get them balanced, realistically it will be a few weeks but I will follow up. At this point I’m just trying to get my Jeep back to its normal vibrations, lol.
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LONGJP2 said:
Swaybar will normally not cause vibrations.
Start with wheel balance.
Click to expand...

It’s been a minute but I let a buddy of mine who is a mechanic drive it and he immediately said front passenger side wheel hub assembly. I changed both driver and passenger side. I am now back to my normal vibrations. Still going to get the tire’s rebalanced because I know some wheel weights fell off.
 
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