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Violent vibration


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Wanted to get some ideas on how to track down my vibration issue. So only between 50-65 mph I experience a violent vibration which seems to be right under the seat or back at the rear. Once pass 65 or under 50 it goes away, and there’s hardly any vibration in the steering which makes me think it’s not in the front end or death wobble. I’ve replaced the trans mount and have new ujoints in the rear drive shaft. Any thoughts or opinions would be appreciated.

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That speed range is pretty typical tire balance, although I think you'd pretty well need a tire to start separating to make it anything I would describe as violent.

Were the ujoints and trans mount done before or after you noticed the vibration?

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1 hour ago, gogmorgo said:

That speed range is pretty typical tire balance, although I think you'd pretty well need a tire to start separating to make it anything I would describe as violent.

Were the ujoints and trans mount done before or after you noticed the vibration?

I noticed the vibration before so I threw those parts at it in hopes to fix. But there was no change. Also I’ve had two different sets of wheels and tires (both balenced) and the vibration was the same with both sets.

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16 minutes ago, BeaterComanche86 said:

I noticed the vibration before so I threw those parts at it in hopes to fix. But there was no change. Also I’ve had two different sets of wheels and tires (both balenced) and the vibration was the same with both sets.

What is the condition and current material of bushings. 

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11 minutes ago, BeaterComanche86 said:

Leafs aren’t cracked and the bushing are worse than I remembered but i found something that doesn’t look right. 

 

Can the sleeve be replaced along with the bushing?

 

 

Yes, the sleeve and bushing are typically sold pre-assembled, then pressed into the eye of the leaf. 

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Just a thought.....can you lay under the truck.....with the rear wheels on jack stands would be ideal but not necessary..... grab drive shaft at the front yoke and see if you can wiggle it up or down or side to side......Just a thought but there is a bearing at the rear of the transfer case.

 

Never had one vibrate....it just blew up :laugh:

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2 hours ago, yxmj said:

Just a thought.....can you lay under the truck.....with the rear wheels on jack stands would be ideal but not necessary..... grab drive shaft at the front yoke and see if you can wiggle it up or down or side to side......Just a thought but there is a bearing at the rear of the transfer case.

 

Never had one vibrate....it just blew up :laugh:

Just tried to give it a wiggle and it’s tight. Had one blow up on a trip back from the beach and that’s when I learned a lesson about proper drive shaft alignment :doh:

 

25 minutes ago, Eagle said:

Tire balance.

That’s what I thought but after having my tires rebalanced recently the problem still persist. 

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33 minutes ago, BeaterComanche86 said:

That’s what I thought but after having my tires rebalanced recently the problem still persist. 

Tire balance.

 

I'm not saying that to be an @$$, but I have found that some shops just can't get tires balanced. I recently found a shop near me that does a very good job balancing tires for all of my vehicles, and as a result of that, they've gotten ALL of my tire work since. If you have a shop nearby that can perform "road-force" balancing, give them a try. Once you find someone that can actually balance a tire, hold on to them for dear life.

 

Also, you may want to consider that your tires and/or wheels may not be round. A tire that's out of round will shake like hell no matter how much weight you throw at it.

 

You'll be able to tell by the frequency of the vibration. Driveshaft-frequency vibrations are usually low amplitude, but are often high enough frequency to be heard as sound as well (an out of balance driveshaft or bad u-joint can present as a "hum" sound at highway speeds). Tire and wheel vibrations are low frequency but can be very high amplitude. If you can feel the individual "pulses" or "shakes" of the vibration, odds are that it is a tire issue, or something else that turns at roughly the same speed as the tires.

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Ok. I’ll throw one in on tires. Dealers do a good job on balancing tires. My girlfriend bought a new car and it drove like a limping horse. Got the tires balanced and it drove straighter than an arrow. 

My two cents on finding someone who will balance tires perfectly. 

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I appreciate all the input and suggestions, I’ll have to call around to find a shop that has the “road-force” balancer and get it taken care of. Seems pretty unanimous it’s a balance issue. Hopefully that will solve my issue, gonna order some leaf bushings while I’m at it :L:

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OP, my MJ has a similar symptom, right at 55-60 mph, there's some vibration coming from the driveshaft. I had it balanced once and they almost got it perfectly balanced but the problem came back after a few months. The driveshaft on my truck is the "rubber sandwich" type, and this rubber is old and coming off causing the imbalance/vibration. I will not get it re-balanced again since I will be installing a lift and the shaft may have to get re-tubed/lengthened. Maybe the problem with yours is at the driveshaft, check it out.

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12 hours ago, BeaterComanche86 said:
Quote

Tire balance.

 

That’s what I thought but after having my tires rebalanced recently the problem still persist. 

 

Too many shops now seem to think that having a fancy machine guarantees that the tires will be balanced right. Nothing could be farther from the truth. It requires a technician who knows (and cares) what he's doing. Maybe a year and a half ago I mounted some new tires on a set of used Cherokee rims I had bought. I had a balance problem. Took them to a nearby tire shop and asked to have them balanced. They reported that they couldn't balance them because all four wheels were bent. I then turned them over to a friend who was (at the time) the shop foreman in a VW dealership. He balanced them -- perfectly. The wheels were not bent, they tracked absolutely straight. All we could figure is that the techs at the first shop I went to didn't know what adapter to use for Jeep wheels.

 

A wobble/shimmy/vibration that kicks in around 55 MPH and goes away at around 60 to 62 MPH is a tire balance problem. I don't know why 55 is the magic number -- it seems to be a constant irrespective of the tire size -- but that's the bottom line.

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