Differential making hollow wine when rolling in neutral

So here is the deal, i recently removed the ring and pinion on my ford 9" to replace the crush washer. After reinstalling(and filling with fluid) i get a hollow whine as the rearend heats up and i put it in neutral and coast. I am thinking about removing the entire third member to have a look at what is inevitably my fault for not researching any torque specs when putting the ring and pinion back in. Does anyone have anythoughts on what i might be looking for i.e. not shimmed properly, bad bearings, worn gears. i'm pulling this sucker out today so any thoughts that might save me from a costly visit to the diff. shop would be greatly appreciated. Thanks Guys!

I'd pull it and if everything seems tight verify that the wear pattern still looks right. It probably wouldn't hurt to verify the backlash and any other torque specs While it's out

While not unusal I would say its probably ok. Many rear ends will make a little more noise on the coast side of the gears. Best bet is to check your backlash which can usually be done just by rotating the pinion although if you have a locker it will feel like it has more backlash than it really does you really have to know what your feeling for. So it might be better to pull it to check it out. Also if you removed the whole ring and pinion last time and didnt torque anything then I would definetly remove it and check everything also use lock tite on the bolt threads.
Also some gear ratios(mainly 3.50) are considered non hunting meaning they contact the same areas all the time if put back together without lining up the marks they may wear differently and cause a loss in preload and backlash which will cause a whine. Usually stock 3.50 gears will have paint marks that should be lined up upon assembly.
Other gear ratios like 4.11 are considered hunting gears which means every tooth on the pinion will make contact with every on the ring.

long before I knew about the non hunting gear sets I rebuilt a rear end without realigning the marks never had a issue but that doesnt mean that it couldnt be a issue.

And at the least I would re-check the torque on the pinion nut. Lots of those come loose after some work being done.
Did you torque it originally to the required forty-three million pounds? Ok, so it's only like 200 to 270 ft lbs for the common Dana axles. I'm not sure what the Ford 9" pinion nut takes, but you get the point. It takes a lot to crush the sleeve.

And curious why you took it apart to begin with? Was it making some noise or acting sloppy already?

Paul

I believe its only 180 with a crush sleeve. He took it apart to replace the crush sleeve. Of course I dont know why he took it all apart or if he actually took it all apart.

so, the reason i took this all a part to begin with was because i had grenaded my u-joint at the slip yolk a half dozen times(I Was 17 with a car that had way more toque and power than any 80's four banger i had previously owned) and mangled my drive shaft and slip yolk. i went to have a custom drive shaft and slip yolk made and they told me they needed the yolk off of the rear end in order to balance everything correctly. Un benounced to me taking the nut off the yolk means you have to replace the crush washer or so i was told. not knowing what i was doing i was refered to another shop to have the crush washer put in. They told me to just un bolt the housing holding the ring and pinion in place and they would install the crush washer and i could bolt it right back in. ever since then i've had the howl. It doesn't effect the performance as far as i can tell, i'm just sick of the noise and assume that it is indicitive of something being destroyed. If this changes any opinions i'd love to hear your input.... Thanks again for all the advice!

I doubt anything is destroyed it probably just has wear and some excessive play. I'm running a set of stock gears that have over 320,000 miles on them and 2 diff blow ups they are still fine. I did have one gear set that started to make noise it was due to the main bearing caps being loose. But it was a spare center that I picked up to run while I rebuilt my blown one. But I didnt check any of the torques before I installed it even though I should have. But still Once tightened back up and the backlash reset it was nice a quiet.

so do you think i should remove the entire third member? Or, should i just start my inspection with the ring and pinion since thats all that i removed before?? luckily i just recieved my shop manual (and discovered this site)from bronco graveyard and am feeling a little more confident about all of this.

I'd pull the whole third member its easier and a must to check everything when its out.

How did you remove the Ring gear if you didn't remove the third member? I think you just mean the Pinion.

I've only done gears in 1 9", but I've done several sets of D44 gears, and the pinion preload, backlash, and torque are all pretty important. I would start by getting the specs and undoing/redoing everthing you did, with the correct tools and numbers. The crush sleeve in a 9" sets the preload I believe.