Grrr, noisy gears

[RatLabGuy]

Ok so I just installed a rear 3rd w/ 5.29s.
Now up front I'll say I don't know the history on the piece or the setup, the guy I bought it from (yes, a member here, and no, no names) said he didn't know and he hadn't run them (project change, yada yada).
Yes, this is a classic case of "don't buy used gears w/o some good info, and esp don't wait a season to install them".

I only did the rear first to check it out.

Anyhow, I just took it out for a short spin (2 miles?) and they are pretty noisy... whine that increases in pitch (and volume) w/ speed - but ONLY when applying gas. popping into neutral or just letting off the gas makes it stop, they sound reasonable.
I did a quick dab of gear marker before putting them in, it seemed reasonably centered, but I'm no expert. unf didn't snap any pics.
I did notice there was very little resistance on the pinion, I could very easily turn it by hand; the old set (4.88s set up at CRS) very much more tight. No obvious wobble/wiggle or anything though.
Any thoughts? i'm wondering (hoping) the pinion nut might just be a little loose?

 

[Cperry]

i certainly saw this coming, and you were worried about white out and vaseline, your needing that vaseline about now

raz over onto tech. could be the bearings are pitted, or the drive pattern has worn poorly. you can't just tighten up a pinion nut unless its a solid spacer but if it had one set right it would not have not come loose. and even if you could you probably won't be able to get those gears to ever run quiet again . centered pattern means nothing heel to tow. should have snapped a pic. basically its worthless, the gears are probably genuine trash need to be thowin in the garbage were they came from the bearings are already knowingly suspect- loose pinion bearing, ect. tonights ECGS preffered nc4x4 member special. on properly set up diff with new precison gears, new bearings, and ill even throw in a solid spacer $399.99 I know your broke but you now have X (im guessing $250) in a japaneese boat anchor.

 

[RatLabGuy]

Well, I guess I'm spending the night pulling it back out and putting the old one back in, I'll do a really thorough inspection then.

I couldn't really tell if they had even been run. No obvious wear or anything.
The bearings (from what little I coudl tell) seemed ok, with the tires back on but jacked up, they sure rolled smoothly w/o any noise.
It soudns fine rolling but w/o gas (torque) applied - wouldn't bad bearings rumble all the time? It's only duirng acceleration/gas applied.

 

[Cperry]

that would be poor drive side pattern. ie on the gas, poor coast pattern if noisy off the gas.

 

[CrashKnott]

I had the exact same problem, only backwards.

I had a Dana 30 and 10-bolt setup with 4.56's (before I got into setting them up myself, or finding a better shop).

Moral of the story, he didn't set the pinion preload right and it backed out. The coast side of the pattern was then fawked, and those bitches got loud! I brought it back and they said the noise was coming from a non-properly lubed pinion bearing (saying my chunk was at too great an angle; which it wasn't), so they threw a new pinion bearing in and I put in a 2 degree axle shim. They didn't do anything about the fact that the backlash had walked, but I don't think it would've helped.

Well, they never got quiet after that and finally chewed themselves to nubs after much frustration.

Time to start fresh!