Driveline Noises

APC9199 · **Posted:** Mon Jul 31, 2017 1:30 pm

I posted this in the driveline noise thread, but it doesn't appear that thread is getting much attention lately. I left it there, so please respond there instead of here so others can find the info if they need to!

So, Ive been busy busy busy replacing parts on my 06 CRD. Heres the list of things I've done so far.

Replaced all 4 wheel bearings and rear seals.
Replaced both front CV half shafts.
Replaced the front intermediate shaft.
Replaced front lower ball joints.
Replaced front upper a-arms and ball joints.
Replaced entire suspension with a Frankenlift II.
Replaced front sway bar end-links and mount-bushings.
Replaced front lower control arm bushings and clevis bushing.
*catches breath*
Replaced rear lower control arm bushings to frame and axle.
Replaced rear upper control arm bushings to frame.
Replaced rear upper control arm ball joint.
Replaced differential fluids front and rear.
Had an alignment done!

So, I started with a CRD that was borderline dangerous to drive on the highway. It would sway from side to side and body-roll horribly around corners. It felt like riding on jello if you shimmied the steering wheel back and forth. It also made clunks and banging noises over small bumps, large bumps, sharp turns, etc. I had a shop do the lift kit and rear upper control arm stuff since I didn't have the time to do it myself in my garage. After tightening one of the front upper control arm bolts, one of the rear sway bar bolts, both front end-link bolts and after having the shop replace one of the rear upper control arm mounting bolts that FELL OUT WHILE GOING 80 ON THE HIGHWAY, I decided to quit taking it to shops for any work. But, after all that, I am clunk free and the steering and ride feel much tighter. I still wish I could get the body roll in corners a little better, but it is good for now.

So, the only thing that is still driving me nuts is the noise that I have posted about here before. When making a hard right hand turn (think traffic-circle or freeway exit ramp), or a long continuous right hand turn at high speed I get a "tire noise" kind of sound. It is a very distinct tire-knob or gear-tooth kind of sound coming from the rear, more so the left side or center, not the right. It only makes noise for approximately half of each revolution of the wheel and is in time with the wheel speed. I noticed something new about it recently. The noise only seems to persist if you're coasting. As soon as I give it a little gas the noise goes away. It took a long time to realize this because I am usually coasting when taking hard right turns. This behavior reinforces my previous thought that it must be differential related, right? Tire noise wouldn't change with a slight touch of the gas pedal if the body remained in the same position, right? I changed the rear diff fluid about 10k miles ago and didn't think to look at the bearings while I was in there, so I might take the cover back off if you guys think it is worth checking. I have also considered doing the outer wheel bearing again just in case I got a bad one from the factory (Timken?!). I'm doubtful of that because the noise didn't change at all when I replaced the rear bearings. I find it hard to believe that two bad bearings would make the same exact sound with the mileage difference and all.

Anyone have any ideas where I should go next?

Also, Dirus posted a video above me in the driveline noise thread which looks the same as the CV's on my Jeep. Is this something I should be looking into?

WWDiesel · **Posted:** Mon Jul 31, 2017 2:29 pm

Just a thought! :wink:

I would check the carrier bearings and most definitely the preload on the carrier bearings. The preload does not allow the carrier to move from side-to-side in the housing if any lateral forces from the axles try to move it. The preload also defines the backlash between the ring gear and the pinion gear and keeps it constant! So if the carrier bearing are worn and are allowing the carrier and ring gear to move from side-to-side a few hundred thousandths, the noise pitch could change dramatically due to the change in backlash between the moving gears. :roll:

Theoretically speaking, the axles should not be able to apply much lateral forces to the carrier since the axles are a free floating design to some degree by being splined into the carrier housing, but I have personally worked on and heard loose carrier bearings make some pretty weird sounds when making turns and applying lateral side forces to the rear axle assembly... :shock:

APC9199 · **Posted:** Wed Aug 02, 2017 2:36 pm

I'll see if I can check the inner bearings myself, and maybe have a shop inspect things further depending on what I find.

Any comment on the video that Dirus posted in the driveline noise thread?

(Also, please post there so the info is "captured" instead of bleeding off the main page in this forum)

APC9199 · **Posted:** Tue Aug 08, 2017 4:32 pm

Can anyone comment on the video that Dirus posted in the Driveline Noise Thread sticky?

flman · **Posted:** Wed Aug 09, 2017 7:05 am

Did you try the tires? Rotate front to rear and see what happens?

I had Bridgestone Revos on at one time and they sounded like a drive line noise.

flash7210 · **Posted:** Wed Aug 09, 2017 8:06 am

APC9199 wrote:

Can anyone comment on the video that Dirus posted in the Driveline Noise Thread sticky?

Regarding that video...
No, the CV axle should not be wobbling where it goes into the diff.
That wobble indicates that the bearings inside the diff are worn out.
In fact, that could be the source of the "whine" noise you are hearing.
If the carrier bearings are worn, that could cause the ring gear to move out of alignment creating a distinct gear whine sound.

You will have to remove the entire front diff assembly to open the cover and inspect.
I suspect that what you find will not be pretty.

APC9199 · **Posted:** Wed Aug 09, 2017 9:05 am

Fantastic! I was going to pull the front cover last weekend but didn't realize how much more work it was than the rear, and didn't have the time so I just swapped the fluid.

I assume I'm looking at bad bearings, best case scenario and a new gearset, worst case?

WWDiesel · **Posted:** Wed Aug 09, 2017 10:03 am

APC9199 wrote:

Fantastic! I was going to pull the front cover last weekend but didn't realize how much more work it was than the rear, and didn't have the time so I just swapped the fluid.

I assume I'm looking at bad bearings, best case scenario and a new gearset, worst case?

If you have ran long enough with bad carrier bearings, it may have worn gear set to the point it may have to be replaced as well. :roll:

If you rebuild it, replace ALL bearings in differential and gear set if teeth are worn. Could get rather expensive!

Another option: Purchase a good whole assembly from a reputable recycler like LKQ and replace the whole unit?

:SOMBRERO:

Driveline Noises

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