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Weird Vibration and Humm


01silvapathy
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Okay so I have been dealing with this strange vibration and humm for awhile now and its slowly getting worse and worse here is whats happening. The vibration starts around 52mph and it feels like a steady paced vibration like you can feel it in your seats and through your body. Its definately on the rear axle somewhere...cause the front hubs are disconnected so nothing in the front is spinning though I guess it could be wheel bearings but the vibe really does feel like its coming completely from the rear. As I accelerate up past 52 it gets louder and louder and you can feel it more and more. But if I let off the gas at say 60, the vibration gets much less if not goes away completely. The sound and vibration also gets louder as the suspension compresses like over a dip in the road the truck will go down and the noise will get alot worse then subside and get back to the way it normally is. I really think that its the ujoints that are causing this. Its only started since the lift was put on really and the truck is just about to 105k. Other things i hear it could be is rear link bushings but thats more of a sway not a vibration or humm or my shocks which the bushings are really worn out on and the body moves up and down a little bit before the shock even moves.

 

As said before this vibration only starts around 52mph its non existant at speeds under 50mph...even when I pretty much floor it from a dead stop it comes in right around 52mph. So im really thinking its the ujoints. Is there any easy way to test if thats the issue? I have a 200 mile trip to school tomorrow so 3hrs at around 70mph get my stuff then make the return 200mile trip at 70 for 3 hours. I really hope she can stay together for the trip...I dont think I can pull the shaft and replace a joint at my house cause I dont have a mounted bench vise or press...but I might have access to the shop when im at school. I just want to be sure that its the ujoints that are the issue first. Any help is greatly appreciated, yall have always been alot of help in times of need :hugs:

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ended with hugZ, i have to chime in now....

 

first thing is first, your rear tires have any feathering/odd wear patterns to them? try rotating them from 1 side to the other to eliminate any riding on top of a choppy worn tread.

Checking the u-joints... are you able to pull the shaft off at your house? if so drop it and at each u-joint "turn" or 'twist' them to feel for binding. If you have zerks fittings in them, would be a good time to give em a shot of greese as well.

 

The lift and added angle on the joints from it proably just shortened the life of a joint that was gettin close to replacement time anyway... weakest link is gonn abe the first to fail normally. Good luck with it and a safe trip :aok:

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I just went outside and put the truck in drive with the parking brake on...went under and tried to spin the shaft. The axle end joint did not budge an inch the trans side did however move like A TINY bit like not even 1/32in. It could have just been my eyes playing tricks on me too but it seemed still pretty tight. Whats the likely hood of a ujoint actually breaking under load while driving at highway speeds? Id imagine it would not be a fun experience and id have to get towed probably.

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I just went outside and put the truck in drive with the parking brake on...went under and tried to spin the shaft.

 

You probably should not have done that without someone to keep their foot on the actual brake. Also, it's not a very good test.

 

One thing you can do to help narrow it down is to drive fast in a safe place, and throw it into neutral. If the vibration disappears completely, it's going to be either the u-joints, or part of the engine/trans/transfer case combo. If the vibration remains the same, it's wheels or bearings etc. If the vibration is a bit less, it could still be u-joints.

 

The pinion shaft in the rear end and the driveline (axis of the transmission output shaft) must be parallel. With your lift, there is no way that is still true, unless you have custom or adjustable length links, which I doubt. Your options for solving this are to either go get new links which you can adjust, or buy a double cardan joint, or try to drop the driveline itself to get it closer to being parallel to the pinion.

 

I think you have three choices here: 1) replace the u-joints and do the trip. 2) run the current ones to failure. 3) Drive something else and use the Pathfinder for nothing but 4x4ing from here on out, and tolerate all of the problems and such that will come of it.

 

I don't mean for any of this to sound rude. I am offering advice that I think makes sense in this situation, even if it's not very positive.

Edited by pathfounder
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Well you also have to keep in mind that these are stock non greaseable ujoints with 105k on them. Parts wear out eventually and I think that this part was going bad and just went out faster due to the lift. Longer links are in the future.

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So its def not the tires causing the issue. Here is what my night consisted I figured id do the rotation myself so I didnt have to drive to ntb to have them do it. Got the rear loosened then moved to the front....and one of the lugs was ceased on Guess somebody cross threaded it and got trigger happy with an impact So I called up to ntb and explained my situation, so I brought it up to them to rotate the tires. I had mentioned something to the guy about my alignment being off and blah blah, my father was with me at the moment and the guy mentioned something about my steering wheel not being straight cause of the steering joint being misaligned....and then proceded to say that its a safety hazard with the airbag and all that stuff. My dad didnt like the sound of that so he said do an alignment (6month 6k warranty) and they would straighten out my steering wheel. So they did straighten everything out and crap but they wound up having to cut the one wheel stud off cause the lug was ceased on. So at the moment im running 5 lugs on the drivers side front wheel So tonight def had its highs and lows. They also forgot to give me back my key to my lock nuts so I have to stop by before I head to Nac tomorrow and pick that up. Also got the spare mounted and balanced for free cause the guy felt bad about messin up the stud Now I just need to see if I can cram it up underneath or if ill be keeping it in the cargo area or roof. Need to make rear bumper with spare tire carrier

 

On the way home I was crusing at 60 threw the truck in neutral and the vibration slowed to a stop so im almost positive its a ujoint issue. I dont have any noises backing up or moving in any direction so it should be fine for my trip tomorrow but then again thats another 400 miles :thumbsdown:

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If it started doing it immediately after the lift I would suspect what pathfounder said is true. If it just started recently the joints are probably gone. Mine are original as well and damn does it shake.

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When I had U joints fail, what I did was jack up the Pathy (all 4 in the air), start it, put it in gear and looked underneath. It was pretty obvious when the I saw the transmission wagging around down there...

 

Do this safely, with jack stands, etc...

 

B

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New u-joints will solve the problem, but they will wear out prematurely again. If they are driven long enough, the vibration will affect the bearings in the rear end and transfer case. The vibration comes from the fact that the rear and the transfer case are no longer parallel because of the lift. U-joints do not have a constant speed as they rotate.

 

The only solution is to use a double Cardan joint. A truck shop could modify your driveshaft to accept one.

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definatly a u-joint issue its sounding now (or as I think about it, I had a trans mount imitate a bad u-joint once), putting it in neutral relived the pressure the driveline puts on them when your givin it some skinny pedal.

 

 

Alot of my family drives stuff that aint at stock heights (both up and down)... part quality, age, and just plain luck is the general way of life of wearable items. Yea, abuse in different ways wears stuff faster but sayin lift is gonna constantly kill u-joints is just ignorant... 2/4 of this site would be putting u-joints in monthly.

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I have no doubt that many/most people can get away with a lift, even a high lift like the OP has, and not have u-joint issues. That does not, in any way at all, change the fact that lifting the truck without dealing with the drivetrain setup is going to shorten its life.

 

There is a reason why there is an entire aftermarket specializing in connecting the ass end of the transfer case to the differential.

 

http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml

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  • 5 weeks later...

Im almost 100% sure its a ujoint issue. Tires were rotated front to back and it changed nothing, I have yet to drop the ds and check the joint but its on my list of things to do. From what I hear if its a roaring noise that most likely means its the pinion bearing cause when bearings go bad thats typically what they do.

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Well what happened for me was I was driving at 70 and heard a noise like a rock in the wheel well then the vibration and very slight noise started, so my first step is to get the wheels re balanced in case I lost a weight (which is what I am hoping). Anyway keep us updated on what happens with yours in case others have the same issue...

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