Rumbling/Grumbling in Drivetrain

[gavin]

So I've had this rumbling/grumbling issue for a while, and finally getting around to really troubleshooting it.

Here's what I've done so far:

Replaced front diff; I know I had botched the carrier install on the first one I regeared, and had other issues with it. No change.

Replace t-case; thinking I botched something in the rebuild or a bad VC, as I had experienced some other issues that may have been related to it (eg, attempting to drive without front d-shaft, high RPMs little movement.)

Last weekend I pulled the front shaft, the rumbling/grumbling significantly decreased, so I bought a new shaft figuring the CV was toast. No change. Back to "normal" with the new shaft in.

Replaced both front cv shafts, one at a time, with no change after replacing either/both.

Wheel bearings; both are good. I did have a bad one, which I replaced with a spare I already had, but no change.

I don't know what else to look at. I feel it in the steering wheel and floorboard.

Since it seems to only appear when torque is applied to the front, I figured it was in the front end; yet there's nothing else to replace.

Rear shaft u-joints are not that old and have been greased numerous times.

Could something in the rear axle transfer that much to the front end steering components that allow me to feel it in the steering wheel?

I doubt it's the torsion twist, as I have checked the ride height per the FSM instructions and I am within those specs.

 

[Turdle]

Hi Gavin

Loose u joints can really throw the sound, and since the transfer case is right under you I can see how it could transfer vibration to the front.

At this point though I think if it was me and i had enough help, I would put the truck up on 4 jackstands, so the drivetrain can work. Have someone hold the brake and apply the e brake, and run the truck in gear suspended. The brakes might cause enough load to make the sounds-

 

[gavin]

I would say it's more of a "feel" than a sound, though there is a noise. Especially noticeable at slower speeds, like 5mph or less.

I'll futz with the u-joints again; I'm wondering if maybe it might just be the flange on one end of that rear shaft. I want to say the last time I replace the u-joints, one of the caps literally fell out. Though the new cap didn't "slip right in" so I didn't think too much of it.

Might be time to hit the junkyard for another rear shaft.

I had thought about getting all 4 on jackstands, just hadn't gotten that far yet.

I might try disconnecting the front shaft and spinning the rear by hand to see if there's any feel; and/or use my mechanic's stethoscope to try and pinpoint any noises.

 

[gavin]

well... not u-joints or rear shaft
got a junkyard unit, put in new joints, and greased the slip shaft. No change.

Another symptom I noticed today is a high-pitched squealing/whine.
The pitch seems to change a bit, not positive but changed when turning.
Anything with the stock LSD that could cause this? Or just a possible diff issue?

Gonna jack it up and turn the tires by hand and get my stethoscope out to see if I can pinpoint anything.

 

[gavin]

Could the issue be something in the transmission?
I have so little experience with transmissions, so I don't really know.
I s'pose I could always drop the pan if I had to, as I haven't done that in a while. Aftermarket pan with drain plug, so hasn't been a need to.

Rear end on jack stands, 1 front tire in the air, transmission in N.
Put the stethoscope on the tranny pan and rotate the front tire; I hear a crackling of some sort. That's on a steady rotation.

 

[gavin]

Well, I definitely have a bad front driver's side wheel bearing unit.

http://vidmg.photobucket.com/albums/v403/cmwgimp/20150530_143854.mp4

 

[Turdle]

That sounded like an impact wrench to me

 

[gavin]

That sounded like an impact wrench to me

bearing feels perfectly fine in the hand.
Also virtually no noise coming from it when off the vehicle, using my stethoscope.
The bearing that was previously on there was definitely bad (grainy when rotated by hand) and I just replaced it with this one a few weeks ago. Only reason I used this one is because it felt fine

Sadly, that was not the (primary) culprit either

No odd sounds coming from the rear end as far as I can tell.

I'm stumped...

 

[gavin]

Transmission be a possibility?
How about rear driveshaft angle? Though the shackles and AAL aren't exactly uncommon.

I'm pretty sure I've had this issue for... a long time.

Now that I think about it, it was there prior to swapping in these axles that I regeared. I had assumed the junkyard rear may have been on its way out and wanted 4.56 anyway.

I don't know if it may have coincided with the AAL install, or even if it started when the shackles were installed.

 

[gavin]

So I think it may be a driveline angle issue caused by the warrior shackles.
pinion is @ 84*, t-case is roughly 86*
and the shackles would cause the pinion to point more upwards.

found this thread by vroomzoomboom, and a post on another forum that lead me to driveline angles.

Now to see if I can source me some OME CR042R leaf springs and get rid of the shackles... or a 2* shim, but I'd still like new leaf packs.

 

[gavin]

so that clicking, squeal, or whatever, was actually coming from the new dri side axle shaft.
The new pass side axle shaft is also adding to the (consistent) high-pitched squeal; still need to put the old one back in to verify.

Installed 2* pinion shims, fat to the back, to point the pinion downward (closer to 90*), but still getting a vibe.

It is more prevalent at lower speeds. When backing out of the garage, when slowing down to come to a stop, it seems like it starts to feel worse. Higher speeds doesn't seem to be as noticeable, but can still feel it (possibly just because I know it's there.)

Only thing left is the rear axle... probably wait until next weekend to pull the cover, as I cannot hear or feel anything off when rotating the tires by hand.
Though I swear the issue existed prior to swapping in this rear axle that I re-geared.

 

[gavin]

apparently I have had this issue, to some extent, since around 2008.
http://www.explorerforum.com/forums/showthread.php?t=203669

heh... decided to dig through my thread history to try and remember what's what.

At that point in time, I had only done the body lift and shackles. I don't believe I had an AAL in yet, and still had the original axles.

 

[gavin]

Ok, attempting to figure this stupid #$*^% problem out.

3 tires in the air (only 2 jackstands.)
I first checked with the front dri side in the air, then went to the front pass side.

Not feeling anything out of the ordinary.
Took my stethoscope to everything I could think of; t-case input and output, transmission tailshaft, transmission pan, front wheel bearing/hub area, front diff, pass side front axle housing, rear diff, rear axle tubes at the axle bearings...

the only kind of odd noise is an extra "whoosh" type sound coming from around the pass side rear axle wheel/axle bearing that I don't hear on the dri side.

So whatever is causing the issue, doesn't seem to occur either without the weight of the vehicle or the torque required to move it...

gonna go ahead and swap out the axle bearings again (I put new ones in when I regeared this axle back in 2010) and get a look at the rear shafts, possibly install my axle-saver bearings with another pair of shafts.

 

[96whitesport]

From reading this thread about 5 times to follow what you have done, I think your answer may be here:

Replace t-case; thinking I botched something in the rebuild or a bad VC, as I had experienced some other issues that may have been related to it (eg, attempting to drive without front d-shaft, high RPMs little movement.)

Last weekend I pulled the front shaft, the rumbling/grumbling significantly decreased, so I bought a new shaft figuring the CV was toast. No change. Back to "normal" with the new shaft in.


I get that the noise was present with both transfer cases, but the symptoms seem like a VC as you mentioned. It also is only most evident with the weight on the truck from your descriptions, I'd bet on the VC especially if you are unfamiliar with the vehicle the case came out of.

 

[gavin]

From reading this thread about 5 times to follow what you have done, I think your answer may be here:

Replace t-case; thinking I botched something in the rebuild or a bad VC, as I had experienced some other issues that may have been related to it (eg, attempting to drive without front d-shaft, high RPMs little movement.)

Last weekend I pulled the front shaft, the rumbling/grumbling significantly decreased, so I bought a new shaft figuring the CV was toast. No change. Back to "normal" with the new shaft in.


I get that the noise was present with both transfer cases, but the symptoms seem like a VC as you mentioned. It also is only most evident with the weight on the truck from your descriptions, I'd bet on the VC especially if you are unfamiliar with the vehicle the case came out of.

I put in a brand new VC on the original t-case when I rebuilt it; though I fully understand it could have been bad from the get-go. Doubtful, but possible.
The vehicle the junkyard case came out of only had ~60k miles.

I still have the original VC that came out of the original t-case, and have been contemplating putting it back in the original t-case, as all the bearings feel/sound good as I checked it while it's sitting on my garage floor.

On the other hand, I didn't get as far as replacing axles or axle bearings yesterday...

Rookie mistake, freak fluke? I pulled the diff cover and found that the carrier had a bunch of lateral play!
I &*^#$% know that I had added enough shims, and added the appropriate pre-load for the carrier bearings. I remember it being a little tough to get it in and needed some persuasion.
I ended up adding a total of about .054 shims. By the time I was done with that, I was done for the day.

I'm glad I removed the spare tire... I have room to sit underneath there without being hunched over!

 

[gavin]

So over the last month, I've been becoming more and more to an agreement with it being the t-case and viscous coupling.
Even (relatively) wide turns at slow speeds, one of the front tires squeals, and it's not a single chirp. Fairly drawn out squeal.
Primarily only occurs in the parking garage at work (smoother concrete), but occurs occasionally on the road too.

Recommendation on where to get a new VC? I've seen them range from ~$290 up to over $400. Tried looking up the manufacturers, but couldn't find any info.

Otherwise, contemplating spending $900 on a rebuilt t-case from Napa

 

[TeeJaytheKid]

Update?

What did you end up deciding?

 

[gavin]

What did you end up deciding?

bought another VC.
Haven't yet had the time to work on the spare t-case.

It makes sense that it's the VC though... recently I've been hearing an odd clunk/clank; usually when backing out of the garage and turning the wheel. It only happens now and again, but once moving it doesn't seem to do it until making a sharp turn.
Though it happened the other day without the wheel turned; so it certainly seems that it could be driveline binding.

 

[TeeJaytheKid]

thanks for the quick reply, i asked because I'm experiencing some kinda growl/grind but haven't gone as far as you into it yet. its almost directly under the driver. i was thinking cv joint on front output because i can feel it in my feet and hear it at all speeds. seems more so at coast. but my m5od makes noise, all 4 wheel bearings(likely more) and my poor transfer case took a beating. Winters coming, so reading things like this gives me hope and some basis to make calls on thanks

 

[gavin]

thanks for the quick reply, i asked because I'm experiencing some kinda growl/grind but haven't gone as far as you into it yet. its almost directly under the driver. i was thinking cv joint on front output because i can feel it in my feet and hear it at all speeds. seems more so at coast. but my m5od makes noise, all 4 wheel bearings(likely more) and my poor transfer case took a beating. Winters coming, so reading things like this gives me hope and some basis to make calls on thanks

If you're talking about the 4405 on your 2000 Sport, they won't be similar causes. Just an FYI.