Baystate Jeepers

Hi Guys
I am trying to diagnose a vibration. I just installed new 33x12.5x15 grabber at2's and have a vibration at 55mph +. The shop that I bought the tires from checked balance twice but unfortunately they do not have a road force machine. I have had this issue since buying the jeep but this is my first set of new tires and I was hoping the issue from from previous used sets. I think the root cause is radial wheel runout. I have 15x10" D window steelies That were on the jeep when I purchased it . I used a 4x4 standing on end resting on the garage floor to try and gauge how much radial runout there is in the tire/wheel combination. They all have some, but the worst one has about 1/8". I also uses a dial indicator to measure the inside of all rims and they varied from 055-.080". Does anyone know what amount of runout would be enough to cause a vibration with this size tire/rim size? Seems like the rule of thumb on the Internet is .050-060" I am thinking of just buying a new set of steelies and having the tires remounted. If nothing else it would perhaps rule out the rims.


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Try rotating the wheels front to back or side to side. The tires being new wont mind the side to side thing. Just to see if it changes or if a rim is bent, maybe an axle shaft. If it dont shake the steering wheel , you might have to look at the drive shafts or U-joints. FjR68

Thanks Frank. I had tried that. New rims seemed to have fixed the issue.


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Hi Guys. Unfortunately the rims didn't fully solve this problem. I am still chasing the vibration. Some more info. I can hear a wuwuwuwu sound that starts at 40 mph. I get an actual vibration on the highway at about 60mph with no steering wheel shaking. Feels like is coming from the back but the sound seems like it's coming from the front driver side wheel but now I am thinking I could be wrong. I swapped front tires. Still there. Removed front drive shaft. Still there. Removed rear drive shaft. Still there. Swapped spare tire to driver rear and than swapped rear driver to passenger. Still there. Tires have been balanced (not road force balanced) twice. I put the rear of the jeep on jack stands and let the wheels spin. I could see some radial and lateral runout in the tire but not sure if it is enough to cause a problem. I pulled the front driver side hub assembly to check the wheel bearing but I couldn't feel any play or anything abnormal. Everything on front and rear suspension is tight. Checked all u-joints. I am running out of ideas except having the tires road force balanced.


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I was thinking shafts but you ruled them out. There's just not a lot left to check and the wuwu noise makes me think u-joint. They don't always have play, they can dry out and semi-seize (ask me how I know)


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Well the only ujoints left are front axle shafts. I have replaced the drivers side ujoint recently and didn't feel anything wrong when I removed the hub assembly. Perhaps I should pull the passengers side and check it even though there is no play. I haven't replaced that one. Maybe the sound is traveling. However I would think I would feel it in the steering. Maybe I have two unrelated problems noise and vibration from two sources. Thanks for your input Carl.


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How much lift ? Is there a T-Case drop ? If its not a drive shaft its got to be a bearing . The proper way to test a wheel hub would be to just jackit one half inch off the ground and get the longest prybar or piece of pipe that fits under the tire. Try to lift the tire and watch the top or the ball joints while doing that. The whole wheel and tire give much more leverage to the hub. How many miles are on the Jeep. It shifts okay , the T-Case shifts good ? Maybe a tranny bearing or T-Case. Do you have a SYE on the rear DS ? With brand new rims they should be fairly true , maybe a bent axle shaft ? Lot of guessin here but were going on what yer sayin ! Noise will travel like you said but something should be able to be found. Keep giving us input . Good luck. FjR68

saf98tj wrote:Well the only ujoints left are front axle shafts. I have replaced the drivers side ujoint recently and didn't feel anything wrong when I removed the hub assembly. Perhaps I should pull the passengers side and check it even though there is no play. I haven't replaced that one. Maybe the sound is traveling. However I would think I would feel it in the steering. Maybe I have two unrelated problems noise and vibration from two sources. Thanks for your input Carl.


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However I would think I would feel it in the steering - agreed. And it's the last place I'd look. But it's possible. Plus, that's about where you are, looking at the last things to check

In the last month or so, I had two cases of u-joints and unit bearings that failed but seemed fine. The unit bearing was whistling at specific speeds. Jacked up the wheel and it had no play and no restriction in rotation but she whistled around 25 MPH and then again at 45 MPH. And the u-joints on my drivehaft? Junk. Made all sorts of ugly noises when I was driving but had no play when I checked them. Trouble was, they bound up when they got warm which *might* be what you're hearing

That wuwuwu was one of the sounds my u-joints were making. It still haunts me at night

I will check them again per your suggestion. Right now I am mad at her and have put her away for a few days while I calm down.


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I did the same thing ! Just closed the door and went on vacation. FjR68

Hi Frank,,
2"'budget boost, 1.25" body lift with MML. The rest is stock. No slip,yoke eliminator. Gears and rear axle shaft bearings redone recently to 4.56 with tru-trac front and rear. 128k miles. 5 speed tranny shifts fine. Transfer case shifts fine. I have checked wheel bearings and ball joints by using a lever. No play. I did indicate the rear driver hub. No lateral or radial runout. Haven't checked the rest yet. My floor jack just blew a seal also. Like I sad time to put it away for a while. I will pick it up next week.


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Check the slip yolk at the T-Case for up and down movement. Some Jeeps end up with a vib after that small lift and some get it at 3 or so. The slip yolk isnt as far in as it would be at stock height. Block the wheels and put everything in neutral . Still sounds like drive train to me. Also , Lightly put you finger tips on the tranny and t-case knobs while it vibrates and see if they feel different before you get to the vib and during. A lot of Jeeps need a t-case drop or a motor mount lift after doing a spring lift to get the rear shot drive shaft in to sync . FjR68

Could it be an engine mount? Does the vibration correlate to the speed of vehicle or rpms of the engine?

Frank wouldn't taking the front and rear drive shaft out eliminate the possibility of driveline vibration?


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BlackNBlue speed of the jeep.


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