Low Frequency Rumble/Vibration

Cowcatcher · **Posted:** Fri Jun 06, 2008 2:20 pm

I started getting a low frequency rumble and vibration under heavy acceleration in the last few days that seems to kick in above 40 MPH. It is speed and load related not RPM and again happens under acceleration but seems to go away at cruising speed. Starts around 40 MPH and seems to stay until around 60 MPH but it may occur at any speed after 40 if I get into the throttle.

At first I thought tires but know I am thinking mechanical like driveline, TC, motor mounts. Seems to be getting worse daily and seems to be worse when cold but that may just be because I am worse with cold.

Any ideas?

msilbernagel · **Posted:** Fri Jun 06, 2008 5:37 pm

I think I can get mine to do this ('05 w/approx 62k miles) under heavy loads. It happens on occasion, and I've just downshifted to make it stop... concerned that if I let it continue I'd seriously shorten the life of whatever it is.

I wonder if it is the torque converter clutch slipping?
If not the T/C, perhaps the clutches themselves.
U-joints are another thing I've heard that might qualify, but I don't think it would be as 'condition dependent' as I've experienced.

My thoughts.

Mark
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Cowcatcher wrote:

I started getting a low frequency rumble and vibration under heavy acceleration in the last few days that seems to kick in above 40 MPH. It is speed and load related not RPM and again happens under acceleration but seems to go away at cruising speed. Starts around 40 MPH and seems to stay until around 60 MPH but it may occur at any speed after 40 if I get into the throttle.

At first I thought tires but know I am thinking mechanical like driveline, TC, motor mounts. Seems to be getting worse daily and seems to be worse when cold but that may just be because I am worse with cold.

Any ideas?

kccrd · **Joined:** Thu Mar 08, 2007 10:35 pm **Posts:** 267

Mine was doing the same thing I replaced the rear u joint with one that is greasable with a zerk fitting the part cost $22.50 from Orielly auto parts the origanal from the jeep dealer was $79.00 the mechanic told me he had only replaced rear u joints on the KJs

msilbernagel · **Posted:** Fri Jun 06, 2008 8:37 pm

Did it do this primarily under heavy load - or did you notice it more often?

Thx - Mark
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kccrd wrote:

Mine was doing the same thing I replaced the rear u joint with one that is greasable with a zerk fitting the part cost $22.50 from Orielly auto parts the origanal from the jeep dealer was $79.00 the mechanic told me he had only replaced rear u joints on the KJs

kccrd · **Joined:** Thu Mar 08, 2007 10:35 pm **Posts:** 267

No it did it under easy acceleration but it progressed and got worse and started doing it under deceleration. It seemed to get worse as it warmed up throughout the day.

BBB · **Posted:** Sun Jun 08, 2008 5:10 pm

We had a low rumble noise at idle and other low RPM cruising and found it to be caused by the fact that the rear tail pipe rubber hanger had worn out. The hole in the rubber hanger wears oversized and the metal post vibrates within the hole :oops:

I haven't found a permenent fix yet other than having it replaced under warranty twice. I installed a worm clamp around the post and hanger to try to get them to stay more tightly clamped for now. Another brand of hanger may work better?

Cowcatcher · **Posted:** Mon Jun 09, 2008 10:01 am

BBB wrote:

We had a low rumble noise at idle and other low RPM cruising and found it to be caused by the fact that the rear tail pipe rubber hanger had worn out. The hole in the rubber hanger wears oversized and the metal post vibrates within the hole :oops:

I haven't found a permenent fix yet other than having it replaced under warranty twice. I installed a worm clamp around the post and hanger to try to get them to stay more tightly clamped for now. Another brand of hanger may work better?

Not that, the whole rig shakes. It is not as bad in AWD.

chadhargis · **Posted:** Mon Jun 09, 2008 12:32 pm

I have had the same issue and it's back again.

I'm betting if you are right at 50mph, and acclerate mildly (not enough to downshift) especially with a load like towing or going up hill, that you are getting a VIOLENT shake that sounds like you're hitting really big rumble strips in the road. It will also happen around 62mph under the same conditions.

This just happens to be right where the tranny shifts to 4th and 5th gears.

I ended up getting a new torque converter, new valve body, and some other stuff that I can't remember. But, that didn't fix it. It's back in less than 10,000 miles. I'm running up on the end of my warraty, so I'll drive around it for now, and get closer to my 36,000 cut off before I take it in. Next time, the bill is on me, and I'm betting it ain't cheap.

msilbernagel · **Posted:** Mon Jun 09, 2008 3:05 pm

That's a perfect description of how it happens...

chadhargis wrote:

I have had the same issue and it's back again.

I'm betting if you are right at 50mph, and acclerate mildly (not enough to downshift) especially with a load like towing or going up hill, that you are getting a VIOLENT shake that sounds like you're hitting really big rumble strips in the road. It will also happen around 62mph under the same conditions.

This just happens to be right where the tranny shifts to 4th and 5th gears.

I ended up getting a new torque converter, new valve body, and some other stuff that I can't remember. But, that didn't fix it. It's back in less than 10,000 miles. I'm running up on the end of my warraty, so I'll drive around it for now, and get closer to my 36,000 cut off before I take it in. Next time, the bill is on me, and I'm betting it ain't cheap.

MACKJ · **Posted:** Tue Jun 17, 2008 9:20 am

Cowcatcher wrote:

BBB wrote:

We had a low rumble noise at idle and other low RPM cruising and found it to be caused by the fact that the rear tail pipe rubber hanger had worn out. The hole in the rubber hanger wears oversized and the metal post vibrates within the hole :oops:

I haven't found a permenent fix yet other than having it replaced under warranty twice. I installed a worm clamp around the post and hanger to try to get them to stay more tightly clamped for now. Another brand of hanger may work better?

Not that, the whole rig shakes. It is not as bad in AWD.

Cowcatcher,
Any luck finding the shake rattle and roll?
I think I have a similar problem but it seems to be worse with the rig in full time 4WD. I can actually feel it shaking stopped at at an intersection, trans in drive. Take it out of full time 4WD and it is much smoother but still there in the 1600 to 2000 rpm rev range.

Cowcatcher · **Posted:** Wed Jun 18, 2008 10:44 am

Haven't found it yet but it is only present from 40 MPH to around 55 MPH. I finally thought I might have a tire bulge or a thrown balance weight so I took it to the tire shop for a rotation and balance but it is still there. I think I will consider an alignment next but I am begining to think motor mount, drive train or transmission issue.

Cowcatcher · **Posted:** Thu Jul 24, 2008 12:23 am

Well, I got a lecture about not having the F37 done and that if it was the TC they would be pretty PO'd. Then they found the failing rear U Joint and replaced it. Runs better than new as there was always driveline slack before. Now.....when it goes again where can I buy a greasable one?

Bill.Barg · **Posted:** Thu Jul 24, 2008 12:35 am

EDIT... Although there is some confusion on the subject, these are the correct joints

I just bought a pair of "super strength" precision brand (MOOG)

PRECISION Part # 269 {U Joint - Non-Greaseable Super-Strength}

from RockAuto.com EDIT... then I returned them and bought Spicers locally.

EDIT.. at first,
I wanted a quality bearing, but did not want the maintenance of a greaseable version.

Then later realized that greasing ujoints aint that much of a task, and since I use the CRD off road quite a bit, the greaseable u joints made better sense

I ended up getting SPICER (Dana) 5-153X u joints qty, two for the rear shaft.

dirtmover · **Posted:** Thu Jul 24, 2008 1:20 pm

This is interesting. There seems to be a number of different failure symptoms with this joint. Mine rumbled only on deceleration below about 25 mph intensifying until the vehicle stopped.

Endurance · **Posted:** Thu Jul 24, 2008 9:22 pm

I am having the exact same issues, its been going on for about 2 weeks now. Im at 45000 miles. Did the new U-joints fix it?

dirtmover · **Posted:** Fri Jul 25, 2008 10:04 am

Endurance wrote:

I am having the exact same issues, its been going on for about 2 weeks now. Im at 45000 miles. Did the new U-joints fix it?

If you're referring to my post, yes it did fix it. You could see that it was a likely culprit since the seals had recently failed - split away but no rust yet - probably as a result of the vibration.

Cowcatcher · **Posted:** Fri Jul 25, 2008 10:49 am

Endurance wrote:

I am having the exact same issues, its been going on for about 2 weeks now. Im at 45000 miles. Did the new U-joints fix it?

yup

I'm at 45K too.

Mine seemed to come on kinda quick. The whole chassis vibrated, particularly in accelleration between 45 and 55. Later it started to do it around 27 and it also begin doing it on decel under 40 to about 30. I also heard a chirp from the rear particularly under 20 on decel which I figured was just something rubbing in the suspension. All gone now and the drivetrain is better than when I bought it.

On that last note, before buying the CRD I rented a 2004 and drove it about 600 miles. There was a lot of slack in the drivetrain and the CRD had it when I got it too. I figured it was a "Jeep Thing". That slack was definately getting worse lately and now it is virtually all gone.

Endurance · **Posted:** Fri Jul 25, 2008 6:27 pm

Thanks guys, this place is awesome.
I called my local mechanic today and told him I would drop off my Jeep Monday or Tuesday.

Herk · **Posted:** Sat Jul 26, 2008 8:22 pm

I had the same issue at 42K I just had the bearings replaced in the rear differential. It was making metal. Problem gone.

On the other issue of the 50 mph shudder my jeep does the same thing since day one even with the 37 mod. I think its pump pressure issue but Im no transmission guy. I have just learned to live it :cry:

Endurance · **Posted:** Wed Jul 30, 2008 7:18 pm

I got both U joints replaced by my local shop today. $170. All problems gone.

Low Frequency Rumble/Vibration

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