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55mph vibration: HELP!

4K views 25 replies 7 participants last post by  dan.stegner 
#1 · (Edited)
Background info on the Jeep:
I am running 4:56 gears w/ 315/70R17 Duratrac tires on stock Jeep rims w/ spacers. The Jeep currently has 73000 miles on it and approx 49000 on the 315's. I also have a budget boost lift w/ Rubicon shocks.
I have been noticing a vibration that is most pronounced at 55mph. I feel it more w/ my feet and hands not in my seat, therefore I am thinking front end not rear. I also feel it more when I accelerate.
So far I have tried the following in an effort to locate the problem part(s):
1. rotated tires (I have rotated them every 3000 miles since new)
2. had tires re-balanced
3. checked torque on control arms as well as trac bar. (I have adjustable trac bars front and rear to re-center the axles after the lift as well as Rancho Geo brackets for caster)- all were tight
4. swapped all 4 tires w/ a set from my wife's JKU (her's show no signs of vibration while on her Jeep)
5. removed front drive shaft
None of this resolved the issue.
I am not at a loss. I plan on pulling the rear drive shaft just to rule it out but it does not feel like it's coming from the rear.
Any advice would be greatly appreciated.
 
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#2 ·
Just a little clarification. Are you saying your Jeep did, or did not vibrate with the wheels/tires from your wife's Jeep?

If the vibration went away with her setup, bat tire or tires, bent wheel, etc.

If it did still have the vibration my next question would be to ask if you removed the spacers for that test? If not, maybe try her wheels/tires without the spacers?

You could also check for a bent flange on a rear axle, particurlarly if you've bounced off any curbs or ruts recently.
 
#3 ·
None of what I tried fixed the issue.
No curbs etc have been bounced :)
No I did not remove the spacers.
 
#4 · (Edited)
Personally, I would remove the spacers and test without them, just in case. Might be worth checking for a bent flange while you are at it.

Just for the heck of it, I'd also scrutinize the front axle u-joints as well. If they fill with rust and get tight they could possibly cause an out of balance feel at speed. Ever notice extra vibration when turning? Or increased vibration after a sharp turn?

Heck, make sure the front hub bearings are good too.
 
#6 ·
Thanks for the input. Someone mentioned using a shovel to test bearing (w wheel off ground a bit)
I have not noticed any extra vibes while turning or after.
I can shoot some brake cleaner in those u-joints too to make sure there is no build up. Too bad I can’t lube them.
 
#8 ·
I wouldn't spray brake cleaner into them unless you are fairly sure they are bad. Brake clean may free them up a bit until you can get new ones if they are bad, but if nothing is wrong with them you'll just wash the grease out of them and ensure they go bad sooner than later.
 
#9 ·
Yeah , fairly easy to do . Let me clarify that by saying that if you have ever worked on a solid axel anything this is pretty straightforward .

Care should be taken when removing and reinstalling the axel shafts so as not to damage the seals in the housing , doing so would be a pain in the ass compared to just the u-joints .

If you have never done it before , have someone work with you that has would be preferred .

Saying that there is a guide spacer inside that you can see with a flashlight that needs to stay in place to keep the knurled splines from damaging the seals .
Look at an exploded view of the axel in question to see what it all looks like to decide if it's something that you would think about attempting .
Personally I have done that kind of repair more than I would care to admit .
To me it's easy but if you have any doubt and can't get reliable help , I wouldn't just guess and thrash .
 
#11 ·
Thanks. I’ve not worked on front axle shafts but have pulled rears before on a full floater axle.
How were you able to tell the u joints were moving ok in o e direction but not the other?

Regarding the brake cleaner- message received.
 
#16 ·
You have a 2015 Jk right? Lift the front tires off the ground, turn the steering wheel to the lock, all the way turned, then spin each tire by hand. If a ujoint is starting to seize you will feel the tire binding and freeing up.
If you take out your own axles beware that the newer JK's have a 2 piece axle seal that may or may not become separated when you pull the axle. If this happens you'll have to pull the diff apart and change the seals. Just give yourself enough time.
This is the seal together and separated.
 

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#19 ·
You have a 2015 Jk right? Lift the front tires off the ground, turn the steering wheel to the lock, all the way turned, then spin each tire by hand. If a ujoint is starting to seize you will feel the tire binding and freeing up.
I did as you recommended before putting the front drive shaft back in. I can in fact hear/ feel a pulsing as I spin the driverside front tire.
I will not be pulling it apart myself as I do not think I have enough time and if I run out I have to way to get to work.
At least it give the mechanic some starting point.
 
#17 ·
all the focus upiin the u-joints is not out-of-the-question but I notice no one has detected nor asked about the MANNER in which OP states he has " had the wheels balanced" & even swapped with his wife's known balance tires/wheels to display no vibration with those.


If wherever he had the tires rotated and 'balanced' did not use a Road Force balancer then there is a very good chance one of these tires has worn just enough to exhibit an out-of-round or balancing issue that only a true offroad force balancing by a suitable tire pro will be able to get them balanced. Do not over look this. Especially if the tires are Goodyear.



I just wanted to add this because few & far-between are the tire shops that can truly balance a larger, heavier offroad tire of 34" or greater.



:jeep2:



 
#18 ·
I completely understand the concept of road-force balancing and would agree that is the best method. Problem is with where I live... no shops near me have the machine to do it.
W/ that in mind I swapped to a more standard size factory balanced set of tires to try to eliminate the tires as the issue.
Thanks for the input.
 
#20 ·
Prob solved, well it will be soon.
On my way to shop for inspection the vibes got worse and were then accompanied by cluncking noises... rear diff bearings coming apart. :(
 
#25 ·
The hits just keep on hittin'
Not bearings, although I will be buying bearings...
Pinion gear lost a few teeth... god only know how since I DO NOT beat on my Jeep and no one drives it but me.
Anyway, I have not seen the gear set yet but I trust the shop so I'll see them soon enough.
 
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