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Hawk37 02-27-2013 06:29 PM

Bearing Whine on Decel
Hey fellow Jeepers,

I've got a loud bearing whine slowing down from anything above 50 mph. It normally starts around 45 mph and quiets down again when I get down to 20 or so. It doesn't happen all the time, and its certainly wheel timed. (speed related not RPM)

So to narrow things down I did a couple of tests. Here is what I know:

I hear the noise generally when I'm rolling with the clutch in, but I also hear it when rolling in neutral with the clutch engaged.

I rev'd through the gears with the jeep parked and the Tcase in neutral, and didn't hear the whine at all.

I also jacked up the rear end, disconnected the front DS and ran it through the gears, still didn't really hear it (The only thing I noticed is some tranny whine, not as pronounced, in 5th, but I hear that's normal for the NV3550)

So, any ideas?

I'm leaning towards the front end right now (hoping its not) One of my axle seals has had a slow leak for a while, but I check the fluid level fairly often and top it off. The pinion seal also started leaking recently too...

TipMeBackOver 02-27-2013 06:38 PM

sound like a diff bearings or outer wheel bearings, and the will normaly only whine with the weight of the jeep on it unless they are really bad, but i would be lookin at buying some outer wheel bearings , there not that expensive, and really not that hard at all to put in

ehron 02-27-2013 06:41 PM

I had a similar sound. My rear diff was the culprit. I could shake the yoke around in the diff by the time I had to replace it. You may want to see if you have excessive play with the yokes.

Hawk37 02-27-2013 08:21 PM

I've got the front shaft off still, I'll check the yoke. I did just replace the rear wheel bearings, (upgraded to a set of superior shafts) but I'll check the front too.

gearswapper 02-28-2013 12:15 AM

Sounds like a pinion bearing to me.

Hawk37 02-28-2013 08:33 AM

The front yoke doesn't seem to have any extra play. Neither do the front wheels. I had a front hub go bad on one of my YJ's in the past, this doesn't seem to be behaving the same.

@Trav - Yeah from what I've been reading the pinion is the only thing that gets noisy only during decel.

I knew I was going to have to tear into it soon to replace the inner axle seal, I was hoping not to have to mess with any bearings and just pull and put the carrier back in.
I've got an 8.8 I was going to teach myself how to set the gears in, but haven't gotten around to it yet... I'd like to do that first as a dry run (not under a jeep either)

If it is a pinion how soon do I need to replace it before it causes more damage? Worn gears, etc.

Dean7276 02-28-2013 02:14 PM

I have the same exact problem. It happens on deceleration between 45-20 mph. Definitely sounds like its coming from the front axle area. I have checked unit bearings, carrier bearings, pinion bearings and everything is in great condition, I haven't been able to pinpoint exactly what is causing it but it has been happening for the past 3 months. I figure It hasn't gotten any worse in 3 months so I doubt it's a bearing.
It started happening after I installed my bumper and winch which added about 150 lbs to the front end. It could be the belts in the tires and the vibes transfer thru the driveline making it sound like its coming from somewhere its not.

95blkyj 02-28-2013 03:13 PM

if it only happens on deceleration most likely its the coast side of you ring gear on your carrier or the coast side of the pinion. or a combination of both. this could just be from old age. i replaced a ring and pinion in a car once that looked fine but made a nice whine on any kind of decel.

it could also be the mesh between the gears. a quick way to check it is to put some yellow gear mess paste on the coast side of the ring gear and check the contact patch.

this is what it should look like on both sides. or close.
^this is the drive side FYI

it could even be the backlash (most likely not, you'd get more of a clunking sound from that)
if you take the cover off and move the ring gear back and forth ever so slightly to feel the backlash in the gears. A good rule of thumb is if you can feel it move and hear it move but not see it its pretty close. now this is NOT the correct way to adjust backlash. you could buy a feeler gauge and check it as well.

personally it sounds like a ring and pinion to me.

let us know what you find it to be. good luck :cheers2:

this also sounds like a u joint problem at those speeds but you wouldnt get a whine from it. it would be more of a vibration. an easy way to check for u joints its to drive it with out the front drive shaft.

ratmonkey 02-28-2013 03:46 PM

usually pinion bearings cause whines or growls on acceleration or deceleration.

Hawk37 02-28-2013 03:52 PM

@Dean - Glad to hear I'm not the only one. Mine's been happening for a month or so now, but intermittently.

I haven't seen any other symptoms, and I didn't add anything to the front. Now that I think about it, I never heard it before I replaced my rear wheel bearings, with the new superior shafts. They're brand new Timken bearings.. I hope one of them wasn't bad. I'd have to pull the shaft and get a new one pressed on... cheaper than a diff job, but still a pain... You'd think it make noise when I spun up the back end though, right?

@95blkyj - I've been running with the front DS sitting in the back for a year. I got a case of the angry sparrows, and its almost as expensive to replace all the joints & ball as it is to buy a new Tom Woods. So my plan is to get a new one when I get her lifted. Essentially my front end is always riding on the coast side then right? Seems strange that it would whine only at certain speeds. I've got a feeler, but I can never find that gear marking compound anywhere outside of a master overhaul kit.. have you?

Dean7276 03-03-2013 01:57 PM

@hawk, after months of thinking my whine on deceleration was coming from the front axle I decided to check the rear. Pulled the driveshaft and found the pinion nut was not tight. It wasn't finger loose but when I put a socket on it (1 1/8 ) I could tighten it easily.
To test if the rear was in fact my problem
I drove in 4wd with the rear DS out and no whine!

I proceeded to remove the pinion nut to clean any oil off the pinion threads and put red locktite on it then torqued it down to 180 ft lbs. Whine is gone!!
This is on a D44 which has no crush sleeve.

It's only been driven about 5 miles so far but the constant whine I had in deceleration is now gone.
Hope this helps.

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