Another new development--vibration at 42 mph

Give or take 3 mph. I get the feel/sound of going over a rumble strip. It only seems to occur when accelerating through the 40-45 mph range, never while coasting. Suggestions of what I should look at? FYI, although my front drive shaft is currently sitting on my work bench, I'm still getting the vibration, so I'm thinking it's probably not related to the rear CV-joint.

This vibration / rumble noise is it coming from the front,center rear?
If you get up to 45 and the noise happens what happens if you put it in neutral?

does it do it when you have overdrive locked out? Thinking it may be converter shudder during lockup.

Are your tires out of balance/alignment/rotation?

I had a similar issue and it was found that I had both a "warped" tire and a warped rotor.

LibertyTC said:

This vibration / rumble noise is it coming from the front,center rear?
If you get up to 45 and the noise happens what happens if you put it in neutral?

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I have tried to triangulate the rumble, but it happens so quickly that I can't nail it down. It's quick nature is also keeping me from doing the neutral test. I'll keep trying to get answers for both questions.

Straight6Jeff said:

does it do it when you have overdrive locked out? Thinking it may be converter shudder during lockup.

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As a rule, I always leave my overdrive turned on. I will turn it off and see if it still happens.

Clyde Frog said:

Are your tires out of balance/alignment/rotation?

I had a similar issue and it was found that I had both a "warped" tire and a warped rotor.

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The alignment is spot-on, but I haven't had the tires balanced in a while. My rotors are in good shape.

Most of the time if you have a vibration at a certain speed, that goes away if you slow down, or go faster, it's a wheel balance problem.

i have an almost identical condition as this in my KJ at around the same speeds. Will be chasing the noise this wednesday in the shop and will report my findings (if any) I'd start with rotating the tires and seeing if the noise moves...

I agree: rotate and balance the tires and see if that eliminates the issue.

Rear u-joints
or right side CV with the intermediate shaft needing replaced as well
Thats if the tires check out OK first

Same problem here. I've said the heck with it for now. I too pulled the front drive-shaft and still heard the rumble. Your description is nearly identical to my problem. I'll be watching this to see if you ever track it down. For now, I don't have the time or money to start throwing parts at it to see what fixes it.

I tried Tommudd's u-joint test (drive for a while then touch to see if warm). They were fine. I'm guessing it's a tire issue, or wheel bearing starting to go. Until it gets worse, I'm leaving it alone.

tommudd said:

Rear u-joints
or right side CV with the intermediate shaft needing replaced as well
Thats if the tires check out OK first

Click to expand...

I did both those within the last half-year, and still have the funky "wump-wump" sound around 45-50 MPH... At this point i'm convinced it's my tires or a funky wheel-bearing in the front...

Stumbled on this post...I to am having the same issue! Wheels balanced, tires rotated, u-joints checked, diff fluids changed (front is leaking alittle...another day), ****** fluid changed, t-case fluid changed. I am almost convinced it is a siezed u-joint or wheel bearings need to be repacked. driving me nuts trying to find this though

i have had this problem for about 6 months. finally last week rear u-joints and the rear yoke both snapped. u-joints are cheap even if you think they are ok you might as well change them and see if it fixes it

Interesting. I drove with the O/D turned off and could not duplicate the rumble. I am now going to try driving with the O/D turned on and try to determine if the rumble is occurring at a gear change.

EDIT: I think this may answer everyone's questions: http://www.jeepkj.com/forum/showthread.php?p=475079 I am going to have my transmission fluid changed, and I'm going to leave O/D off until I do. I don't really have $1700 for a new torque converter.

mine doesn't sound like that issue...the issue in that link is from the torque converter locking up, and as the owner stated, would only last about 10 seconds...mine will do it all day long. mine feels more like a vibration than a shudder.

I have been experiancing the same issue but only in snow/slush conditions.
Even when I removed the front DS it was there.

Happens a little more frequently when in 4WD.

It's funny. As I have been searching the web for answeres it seems to be a common problem with no real remedy.

What I find most preplexing is it only happens as the speed hits and passes 70KMH (I am in Canada eh) Then as it falls back under 70 it comes back.
Only for a second or two then it goes away.

mine does this. so did my 03. I think they all do it just some more than others. What is really surprising is that nobody seems to know wtf it is. I call it the "45 MPH wtf is that?". It may be what Tommudd suggested because nothing simple seems to fix it.

edit:
I'll add that I've had my 04 since 3000 miles and it did not do it until it had about 36K on it. So, maybe it is something as simple as u-joints. I just hope it isn't in the front. Not really in the mood for that, but that's just me.