Topic: Odd noise coming from below the Jeep

[jfrabat]

I need your help; I have an odd noise that I can hear coming from below the Jeep (transmission?  TC? DS? Pinions?) when I drive at speed (40 mph or more) and I match the engine speed to the Jeep's speed (what I mean is that I cannot hear it when I am accelerating or coasting in N).  At this time, my main suspect is the front DS; the rear DS has very little play, but the front I can twist a couple of degrees when I climb under the Jeep.  It is certainly not twisting at the U joint, though, so it is not that.  My second guess is that the TC chain is stretched, and it is hitting the case.  Any other things I should look for?  Or any ideas to narrow down the source of the noise?  I cannot exactly go under the Jeep at 40 mph, so I cannot hear exactly where it is coming from...  So any idea is greatly appreciated!

[sharpxmen]

do you still have the vacuum disconnect? if yes then the front d/s won't be turning.

[neale_rs]

What does it sound like?

[jfrabat]

do you still have the vacuum disconnect? if yes then the front d/s won't be turning.

No, that's long gone...  I have solid axle, so the front DS is always spinning.

What does it sound like?

It is a rhythmic sound.  In all honesty, sounds like a bad bearing or something, but it is difficult to hear, as I have to listen from outside the window (it does not come through the tub; it's not loud enough for that).  Kind of a whooom, whooom, whooom, whooom...  From what I could tell a couple of nights ago, the rhythm is more related to speed than gear, which kind of leads me to believe it's either the TC or a DS...

[grumpygy]

Think I read it on here, is your front drive shaft balanced since they do not come balanced from the factory.

[sharpxmen]

i hope is not the R&P, that's how mine was making noise when the rear went bad, but for the front i don't know.

[Jeffy]

If it sounds like a bearing, I'd check your driveshaft angles.  Mine does something similar when I lift off and coast at 65-70.

[neale_rs]

Disconecting the front DS would start the process of elimination.

[jfrabat]

Think I read it on here, is your front drive shaft balanced since they do not come balanced from the factory.

Yes, I think it is...  IIRC, the old one died and I had to replace it, but I'm not 100% sure on that one.

i hope is not the R&P, that's how mine was making noise when the rear went bad, but for the front i don't know.

Well, I do have rings and pinions here in my garage, so if it is, it would just be labor...

If it sounds like a bearing, I'd check your driveshaft angles.  Mine does something similar when I lift off and coast at 65-70.

Could also be...

Disconecting the front DS would start the process of elimination.

Actually, I think I will start there.  Don't know why I did not think about that myself, but I'll get on it tomorrow!

[chardrc]

sounds similar to when the pinion bearings went out on our zj. wouldn't make noise under power or slowing down but if you coasted or feathered the throttle jsut right it would make the sound as you discribed. but may also be the front ds as others noted.

[Jeffy]

If it's the pinion, you should be able to put pressure on the yoke and see if there is any movement.

** I was thinking, you'd probably get the noise in all gears and speeds if it was the pinion bearing.

[jfrabat]

Well, unfortunately, I decided (MY decision!) to do some housework last weekend (it's what I REALLY wanted to do; I decided it all by myself because in my house I am the boss - by the way, my wife gave me permission to say that!), so I did not take the front DS out.  But I did get around to recording the sound.  If I figure out how to attach an MP3 here, I can share with you guys, but I cannot figure it out for the life of me!  I did make a video to record the sound as well, so if I can't figure out how to load the FTP, I will have to go that way (although the video part of the video is worthless, at least you'll be able to hear the sound).

[neale_rs]

Men always get the last word ......  "yes dear"   

[Jeffy]

Well, unfortunately, I decided (MY decision!) to do some housework last weekend (it's what I REALLY wanted to do; I decided it all by myself because in my house I am the boss - by the way, my wife gave me permission to say that!), so I did not take the front DS out.  But I did get around to recording the sound.  If I figure out how to attach an MP3 here, I can share with you guys, but I cannot figure it out for the life of me!  I did make a video to record the sound as well, so if I can't figure out how to load the FTP, I will have to go that way (although the video part of the video is worthless, at least you'll be able to hear the sound).

You can always upload it to youtube as a video file.  There's also Sound Cloud.

[jfrabat]

HAd not heard of SoundCloud before, but just opened myself a new account...

OK, here's the link to the recording.  This is what you are hearing:

I start the recording inside the cab going at about 35~40 mph.  I open the door, and put the phone as far under the Jeep as I can reach.  I step in the gas in 4th gear, and then let it coast, then step on it again, then let it coast, then take the phone back into the cab and shut off the recording...  Any ideas what it could be???