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Stock Jeep.. Bad Vibes

4K views 34 replies 10 participants last post by  1BLKJP 
#1 ·
Ok.. I havent even modded my darn Jeep and I am getting Vibes :chair: :evil2: .

I checked the U-Joints, they seem ok. Only thing out of wack I can see, is a pinched sway bar bushing. Everything else looks tight and good-to-go.

Jeep Background: Transmission was replaced 5,000 miles ago. I am also getting some slight bump steer. The wheel doesnt turn all the way around, but it does feel like the steering wheel looses connection with the Jeep when hitting larger bumps at high speed, untill the suspension stops jouncing. Seems like it "reconnects" when the suspension settles. I think its normal personally, but I was told to mention it :p

Vibe background: Front MT/Rs were cupped REAL bad, I put them on the rear 1,500 miles ago. Before I put them on the rear, I was getting some nasty vibration sounds from the brakes but no felt vibes. The tires now appear to be cleaned up. They are not visibly cupped like before. I did a couple 10 second burn outs in 2nd on my slanted driveway during a torrential downpour we just got, to make sure they are evened out. They ARE still pretty noisey, the rears make a loud whomp whomp supper swamper type noise that is audible untill about 25 on my Rubicons radio. No noise from the fronts at all.

The Vibes are intermittant. One day they will be horrid (Enough to vibrate the seat) the next I wont feel any at all. Most the time I feel a small Whuump Wuuump vibe at highway speeds (~60). It sounds and feels almost like somethings out of round. The vibes are in the FLOOR and seat, NOT steering wheel. The noise and vibration is SLOWER than the loud azz whomp of the MT/Rs. The vibes at highway speeds arent bad at all, I could live with them.

The bad vibes are at 8-14mph. Decel from 15mph to 8 mph (either 1st or 2nd) gets bumpy enough jar my teeth some days. It also does it accelerating, or cruising, between that speed in either 1st or 2nd, but I notice it more decelerating. The vibes are bad enough to make heatshields go nuts, things in the jeep, like wrenches etc., vibrate audibily against each other, but nothing is felt in the steering wheel. The best way to descibe it, is running over a rumble strip between 8-14mph, but not as bad. Again, I also feel the vibration in the seat. The Jeep vibrates like a rumble strip, but the seat vibe feels like something way out of round. Does that make any sense?

During the highway speed vibes, putting the jeep into 4wd does not make the vibes go away, but it does calm them down some. It seems to "smooth out" the out of round feeling, and makes it less severe, but the problem still exists.

I am thinking this is a rear tire issue. Maybe the rear MT/Rs were just way too far gone, and the tire has worked itself out of round. You all think this is a tire issue, or should I be looking elsewhere? I thought U-Joints first, but they seem ok, than tires, but they look smooth now, not cupped. Then I thought trans again, but it does it in 1st AND 2nd, not just 1 gear. I cant really take it to the dealer untill I KNOW whats wrong, since they cant even fix a gushing oil leak thats starting them in the face...

Thanks guys..
 
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#3 ·
:chair: I hate you scout. :wavey: I think Mr. Clifford wants to open a Jeep dealership next to my house, and have Jerry be the lead tech. I cant even get these people to plug an oil leak thats dripping onto their face, let alone get them to DIAGNOSE an issue!! I need to know what it is before I take to the dealer :)
 
#4 ·
First thing that I would physically check instead of "Everything looks tight" would be to make sure all of the components in the front end/steering/sway bar links is tight. Including the trac bar.

Second, how do you get a vibration noise from the brakes without actually feeling a vibration. Are your rotors warped?

Third I would say that most definitely you need to either do or have an alignment done. How does your jeep track on a flat surface? When you turn a corner does it want to continue turning or does it start to track back straight? This also can have something to do with your tires cupping. Also if you rotated them 1500 miles ago it will probably take maybe even another 1000 miles before those rear tires wear flat. MT/R's are known to get upwards of 45 or 50k miles on them before wearing out. This could be a major cause of your vibrations also.
 
#6 ·
Everything seemed to be tight, I got a wrench on all suspension components. Only thing that could be considered loose was the whole assembly pivoting on the zerk fittings, but I assume thats normal.

By brake vibration, I mean the dust shield would vibrate against the rotor. It was not bent too close or anything like that, the vibrations are just that bad at real low speeds :p I bent the dust shield farther away from the rotor. More brake dust on my wheels, but they still do it if I put the MT/Rs that are cupped, up front.

I had the Jeep in a shop for an alignment the other week, and the tech said it was all so close it wasnt worth paying for an alignment. If you let go of the steering wheel, it tracks straight for ~30 yards than starts to pull to the right. Coming out of a turn, I let go of the wheel and it wants to straighten out.

The more I think about it, It has to be the MT/Rs. I was having vibes up front before I rotated them, and now the vibes are in the rear. It feels almost like a U-Joint, or a rear end about to blow (checked diff fluids, they are all good.. very little metal). I guess I'll just keep running it and see whats happeneds. Worse comes to Worse, I get a day off :D Maybe this weekend, I will have Mr. Tire balance all 4 and do the alignment, no matter how close it is. Is the 1/16 to 1/8th of an inch a standard Jeep setting, or is that the internet setting. In other words, should I tell them I want the front 1/16th to 1/18th of an inch toed in from the rear, despite what the computer says?
 
#7 · (Edited)
It could be the rear tires but where you feel the vibration (in the seat and floor) shows a possible driveline problem also. If you haven't already done so I would check all the mounts for the trans/engine, and the bearings in the rear axle/pinion. My MT/R's have a vibe problem and they vibrate all the time not intermittently. You also said that the trans was replaced a few thousand miles ago. I wouldn't rule this out either.

Might also be a slung weight, I have seen stranger.
 
#8 ·
hey scrumpy I will give it a look over when I get up there something to consider is your suspension.. you did manage to lodge something under your coil spring. it could have something to do with that or it could be the fact that your running a tall skinny digging tire thats got high milage on it.. I'll go over the back end of this grumpy bastard this weekend
 
#9 ·
kewl, thanks man. I really think its either the tires or a u-joint though. Bring up a set (2) of 31s on a rim, or just bring grumpy. well swap em out and see what happends. Just make sure the lug pattern will work...you got enoug trucks, bring something to swap with for 10 mins

BTW, that rock that got under my coil spring is kim's pet in our room :D
 
#10 ·
Now that you've checked everything in progression I would say that it's your tires also. I just always check the things that "Could" be wrong and rule them all of the list first. My rig gets a bit of a vibe at slow speeds and I know that it's the tires, especially since mine end up chunked pretty good after a year or so. :D
 
#14 ·
Seems we have found the problem. I took it light wheeling today, to try and isolate where my problem is. The first steep hill climb we got to, we heard some loud popping from the rear again. This time, it was bad enough that we decided NOT to isolate the sound, and just to get it back home and find the problem with our eyes.

Penguin_in_a_cj called while we were on our way back, so we decided to wait untill he arrived (about 30 mins ago). As soon as we crawled under the rear end, we both noticed the LR upper control arm did not look right at all. I went up front, and began bouncing the Jeep from the front bumper. After about 3-4 bounces, the rear started making the same click with every bounce. About 30 seconds later all I heard was "Oh @$%@."

I figured that was my cue to stop. He simply handed me the flashlight, and went up to the front. I crawled under it, took a gander while he bounced.

The bad: Ya. Well, you now how if you roughly measure the gap between your control arm, and the mounts, its a bit more than your finger? On the LR at the axle side, the UCA was about half a finger width from the mount. It appears the entire UCA bent about halfway down, and torqued out of spec both laterally and longitutionally. Everytime he bounced the front, you could see the LCA, and the UCA at the outer joint (towards the engine) try to pivot at the joints, the control arms would flex some etc. At that joint (the UCA Axle joint) there was ZERO flex. The control arm is so torqued, it appears that its binding at that joint and putting all its force into the bolt and mount. Both LCA and UCA also apear to be flexing sideways (I assume its because of the bind).

The tires are also no longer cupped. Instead, he used the term "feathered." Its like, the front of a lug is higher than the back of the same lug (make sense?). The U-Joints are also popping because it appears the angle of the D-shaft is slightly off (I assume its because of the control arm). With 2 very petite females in the backseat, the vibes are much worse, and the driveshaft is almost flat! Ill take some pics tommorrow when its gets light.

Needless to say, I think the previous owner (ya the one that destroyed a trans in 18,000 miles...) completly azz raped this Jeep. Now I gotta figure out how to get it fixed. My dealer cant even fix a gushing rear main leak, I dont know how I am going to try and explain a bent UCA........:chair: :chair:
 
#15 ·
Doesn't surprise me. Those stock uppper mounts are not very strong. It's another thing that you have to wonder what the boys at DC were thinking.
 
#16 · (Edited)
1blkjp, would that cause my alignment to be all kindsa hay-wire in the back, and the vibes? I think it would, but I just want to make sure that there isnt another problem I am overlooking, because a problem was found.

EDIT: Is this a common thing? Does the upper control arm usually bend, or the MOUNT bend? What is the fix? It looked to me that the mounts were ok, it was the actual upper control arm that was bent, but I may be wrong. I assume its only the arm being replaced, if it infact is bent? If its the mount, can they just bend it back, or do I have to trust someone else's welds on my rig?
 
#17 ·
Oh yeah bro. That can be all kinds of your problems. You are now effectively changing your pinion angle with every bump, gas pedal change, brake engagement. I'm sure it's what is causing pre-mature failure of your dshaft ujiont also.
 
#18 ·
:( Alright man, thanks. I wish some of you guys were techs at a dealership here though. When I take it in, its like I am talking latin to them, and they can NEVER find a problem. They couldnt even repllicate a clutch squeak with the top/doors off when all ya had to do was push it in :p (did that to see if they even LOOKED at my Jeep...).

If I take some pics, would you be able to tell if the mount was bent, or the control arm?
 
#20 ·
JC that arm looks mangled my friend. I can't tell from your pics, but is the frame mount for that pass. upper ripped any? At the very least it looks like the bushing is fried at the axle end.
 
#21 ·
No, the mount welds are good on both passenger and driver side. I looked them over good, they all also look to be straight and not bent (both sides have a slant to them, but the angles look the same, and they slant opposite ways).

I am just wondering if its only that UCA or if I have other issues too. How the heck do you bend a control arm anyway :p
 
#22 ·
By over flexing the bushing in there. However with that one it usually starts to take out the bracket also. I'll see if I can find a pic of what I'm talking about. I know there was a local guy here that ran into that recently.
 
#24 ·
Thanks, thats on the side right? The side facing the pumpkin? I will look for a small crack around the mount on both UCAs today when I get dressed.

thanks 1blkjp. Should I just tell the service writer that I am having loud popping issues from the back, and that I am 99% sure its a bend UCA, or should I let them find the issue?
 
#25 ·
1blkjp, upon closer inspection, I DO have that failure on BOTH of my UCAs. I also have a small dent in the corner of my gas tank skid. My father is a used car manager for a large chain out here, and they have a Jeep store. He is telling me that Jeep is not going to cover a bent suspension component since I have been wheeling. He said the scratched up wheels and skids will tell them its been wheeled, and that they will classify is as "collosion damage" from offroading :confused: . As I said on another forum, I can count the hill climbs on one hand, I have always been careful with the skinny peddle, and I dont remember ANY had hits. I can remember dropping down onto the gas tank skid, but NOTHING that would be the UCA.

Lets see what happeneds when it goes to the dealer. Ill make an appointment monday. If they wont fix it though, looks like I might have to sell the Rubi and get another Jeep :( :( :chair:
 
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