More rear end mysteries.

So heres the issue, old dana35 was making a rubbing noise. Pinion slop due to inner bearing. Bought a 8.25 and swaped it in. Now im getting a howling noise that increases with speed

Doesnt happen in nuetral so i dont think its wheel/ axle bearings or carrier beatings. No slop in pinion, could it be a bad mesh between ring gear and pinion? I tried tightening the pinion nut to see if it was loose. Very tight, but theres only two threads showing . Getting frustrated


Itsnot tire noise.
Fluids are all good tcase and tranny need a fluid change but im confident thats not the issue.

Gonna recheck fluid in rear diff, changed it when i swapped it in.
I dont think is drum noise.

Am i missing anything?

Thanks guys. Idk what to do, i guess i gotta drop the cover again and inspect the gears and carrier and wheel bearings

pinion angle?

Sounds like you replaced one noisy axle with another.

Was the 8.25 from a known trusted source or a CL "perfect condition" seller ?

Howling is usually bearing noise. From FSM:

The axle shaft, differential and pinion gear bearings
can all produce noise when worn or damaged.
Bearing noise can be either a whining, or a growling
sound.
Pinion gear bearings have a constant-pitch noise.
This noise changes only with vehicle speed. Pinion
bearing noise will be higher because it rotates at a
faster rate. Drive the vehicle and load the differential.
If bearing noise occurs the pinion rear bearing is
the source of the noise. If the bearing noise is heard
during a coast, front bearing is the source.
Worn, damaged differential bearings usually produce
a low pitch noise. Differential bearing noise is
similar to pinion bearing. The pitch of differential
bearing noise is also constant and varies only with
vehicle speed.
Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changes
when the bearings are loaded. Road test the vehicle.​

Turn the vehicle sharply to the left and to the right.

This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise​

is usually not noticeable at speeds above 30 mph.

souske said:

pinion angle?

Click to expand...

What should it be/look like? Accurate way to test?

dktool said:

Sounds like you replaced one noisy axle with another.

Was the 8.25 from a known trusted source or a CL "perfect condition" seller ?

Click to expand...

CL. My brother picked it up from a guy at a shop, had a few jeeps. Seller said he swapped in a ford 8.8 he took from hi old xj. Seller said he drove on the 8.25 for about a month no problem.

XJFrankenstein said:

Howling is usually bearing noise. From FSM:

The axle shaft, differential and pinion gear bearings
can all produce noise when worn or damaged.
Bearing noise can be either a whining, or a growling
sound.
Pinion gear bearings have a constant-pitch noise.
This noise changes only with vehicle speed. Pinion
bearing noise will be higher because it rotates at a
faster rate. Drive the vehicle and load the differential.
If bearing noise occurs the pinion rear bearing is
the source of the noise. If the bearing noise is heard
during a coast, front bearing is the source.
Worn, damaged differential bearings usually produce
a low pitch noise. Differential bearing noise is
similar to pinion bearing. The pitch of differential
bearing noise is also constant and varies only with
vehicle speed.

​

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Click to expand...

http://www.youtube.com/watch?v=41Khbsp05Uc

http://m.youtube.com/watch?feature=plcp&v=0TaBa0xqPY8

I think these came out pretty clear. Sounds good on my phone

Weeeeewrrererr.

Any one listen? Possible acoustic diagnosis?

To me it sounds like mud tires going down the road and dodging pot holes. A low speed howl like this sounds like wheel bearings maybe carrier bearings. Not sure how fast you were going as pinion bearings usually don't start to whine until over 30 mph. Pinion bearings would have a higher pitch sound to them too. Also with pinion bearings they will whine when under power and taper off when coasting.

This whines under power and tapers after coasting. I was goin down the street in between red lights never going over 35/40mph

Some one suggested to me that the noise could be the milimiteres of difference in gear mesh due to new angles of my xj vs the donor. He said it may go away.
Sounds fishy tome.

I could not hear anything significant.

The way I check my differentials. Take the drive shaft off and slap the side of the pinion yoke, any movement is cause for concern, an audible click and you may have serious problems. I spin the yoke with the wheels and drums off, you can sometimes feel/hear bearing play.

With the drums off push up on the axle, a tiny amount of play is to be expected (.003-.006). In and out play doesn't mean much.

With the end cover off of the differential, pry up on the carrier with something at least 18" long. You can feel any significant carrier bearing play.

Most times when my carrier bearings were going out, it was louder in reverse than forward.

I catch the oil out of the differential in a clean catch pan and check to see what comes out besides oil.

Bad bearings, pinion or wheel are usually accompanied by seeping or leaking seals.

Tiny amounts of noise I ignore, I've driven some moderately noisy differentials for years.

Use 140 gear oil and half a pint of molybdenum gear additive and halve your noise.

Drive train noise will fool you, it can be one of the harder things to diagnose. I've had hubs sound like the noise was coming form the transfer. A trick I use is to drive next to a large building wall or a brick wall, with the passengers side windows down. The echo can help you to localize the origin of the sound, front or rear. I've seen mechanics swap out wheel bearings and the noise to end up coming from the rear tranny output bearing. Noise will fool you.

My front pinion seal has been seeping for around six years now, I've never had to add any oil. A little oil can look like a lot.

Aha, im gonna change my tcase fluid and add some moly. Any good additive suggestions? Im assuming i cant buy strsight molybdenum, probably an additive that has molly in it right?

****^ adding moly to diff

Adding moly to the transfer case is a BAD IDEA IMHO.

96xj-A-skwad said:

Aha, im gonna change my tcase fluid and add some moly. Any good additive suggestions? Im assuming i cant buy strsight molybdenum, probably an additive that has molly in it right?

Click to expand...

"This whines under power and tapers after coasting" - this sounds like rear pinion bearing to me...

Ecomike said:

Adding moly to the transfer case is a BAD IDEA IMHO.

Click to expand...

I Meant adding to diff sorry.

http://ringandpinionservice.com/diagnosing-problems

Dunno how accurate this is, but this might help someone in the future.

I have no play in my rear yoke, so im guessing its the inner pinion bearing, OR my gears are shot. Havnt had time to open it up yet and im still drivin on it. No other choise though.

The nose cone area on an 8.25 is longer then a D35. Did you change the driveshaft to the correct one?? If not the driveshaft could be to far into the transfer case hitting the end of its travel there and binding a bit.

Looks like you are replacing pinion bearings sometime in the future. If you can live with the noise, they will most likely go for another 25-50K miles. I'd have to hear it with my own ears though to make a better judgement call.

I put in a D44 a year or so ago with whining pinion bearings and have gone 15K with no problems as of yet and no fine metal flakes in the oil. I'll be replacing all bearings this summer at some point.

Im on 3" of lift and also verefied that i have enough travel in the original drive shaft.
Gonna replace all bearings soon. Done alot of reading and at first this task looked like a job for thr pros..... but i know how to use a torque wrench and dial indicator so im straight.
Now i just need the time.