2012 Unlimited Sport - Vibration Or Grinding Noise At 9/10 MPH

Meety Peety

New member
Hey guys, I am having an issue where I hear some sort of grinding or vibration when running at 9/10 MPH. It's pretty consistent and does not stop after a few seconds, if I maintain 9MPH, it will maintain the vibration. It's hard to pinpoint exactly where it's coming from because it's fairly feint, but it sounds to me like its from the front axle. With the windows down it feels and sounds similar to driving down a mild washboard dirt road, except the suspension isnt really moving or anything, you really can only barely feel it in the pedal. The sound is definitely more present then the physical vibration.

It doesn't really bother me, but I can't help but worry that it is a sign of something going wrong and I'd rather get it figured out now and not find out what was wrong out in the desert somewhere. Being that this vehicle is also my daily driver, it does get quite a bit of road miles as well. When I notice this the most is sitting in stop and go type traffic. It happens just about every day. This will happen regardless of accelerating or decelerating and with or without braking. If I am going 15 MPH and I let off the gas, it will make the noise as I'm slowing down through 10 and then 9 MPH, then stops around 8.

A little bit about the jeep, it's a 2012 unlimited sport auto with about 83k on it, 3.5" lift, 35" dynapros, bumpers, crushers, rock sliders, winch, etc. A good amount of weight added to it. Recenty (10k miles or less) had it regeared to 4.88 and started towing a light load (+/- 2k#) every so often - about 6 trips so far. Followed a proper break in for the gears and had them inspected and new oil at 500 miles.

I never noticed this until the regear, but you tend to be more aware of things after you have them worked on as well. I have heard of people experiencing "chatter" after a regear, but not sure if this sounds like the same thing. What do you guys think? And is this a sign of impending destruction or just another new "noise" I have to get used to.. I am probably ok with that.. my jeep makes a lot of "noises" haha. As long as it's not something that I should be fixing and not ignoring. Don't want to break something at the worst possible time if I could have prevented it you know?

Any other components should I check that could be the cause?

Thanks in advance for all of the knowledge. I don't post much but I read and read trying to learn as much as I can.
 
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BobNH

Member
The only input I have is that when I changed the pinion seal in my TJ, I had a similar vibe. Turned out I had not got the pinion nut fully torqued.
And, when I went to 4.88 in that same TJ, everything felt different. Any minimal driveline vibes will be considerably more now because your drivetrain is spinning considerably faster now. It could be you had driveline angle issues that are now exacerbated with the increased rpm of the drivetrain. This was the case in my TJ, having gone from 3.07 to 4.88.
Good luck

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WJCO

Meme King
Remove your front drive shaft and see if it goes away. That should get you pointed in a good direction for diagnosing it.
 

Jeepfan30

Member
After a bad re-gear I had a similar sound and it turned out the front pinion bearing was toast, smelled toasted and had marks inside the race. Me and my friend replaced the front pinion race and bearing and now it's just like new. My friend was a chevy mechanic so I got lucky having help me. Hopefullly yours is not what mine was, but sounds similar. Almost like growling at low speed, but couldn't hear it over 15 mph.
 
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