So I regeared recently and just got done with changing the oil after the 500 miles break in period. Today I noticed a problem. I got on it a little bit today and right after I noticed a gear whine from my rear Dana 44. This only happens during coasting and is completely silent during acceleration. When I changed the diff oil I took the covers off and inspected everything and it all looked good. The only thing I changed was the oil that I used. I had a truetrac installed when they did my gears and Eaton says to use non synthetic with no LSD additive. I think the place that did my gears did the opposite with additive and synthetic. The place that did my gears is highly reputable and Jeep Wranglers are their speciality. Oh and I felt the diff cover today after the drive and it was extremely hot! Not sure if the oil is the problem or the gears not installed properly. Please any advice would be appreciated!

 

Well if I were you I'd call the shop , take it in and have them check it out . Maybe incorrect back lash ? You did your heat cycles to break in gears !
As far as the gear oil all synthetic gear oil has LSD additive in already. ( so I've been told ) know it's not recommended by Eaton, I have trutrac in front diff
And I run Amsoil 75-140 syn with no issues...

 

Yea I was going to call them tomorrow, I did exactly what they told me to do in order to break them in. I had no issues at all until today. The oil was the only difference that I can think of.

 

Do you know if they use a new master install kit , carrier bearings , pinion bearings etc....?

 

They used a master instal kit. I had them get me 4.56 gears with master install kits along with truetrac front and rear.

 

Some diagnosis info from randys:
Technical Help


And a quote from the folks at Dynatrac from an older truetrac thread:

There are quite a few posts from people running truetracs with synth and having no issues, but ya gotta think that maybe there is something to it if every one of the truetrac issues brought to dynatrac were related to not running dino.

 

So here is an update: so I had it down at the jeep shop and they changed my differential oil. They said that was the problem because I used the wrong gear oil. How can the wrong gear oil cause this? Oh and nothing really changed because I still hear it while it coasts. They then told me to allow the new gear to break in the coast side and I head back to them next week.

 

If u are driving straight and let go of the gas and coast and still hear gear whine, it isnt set up properly. In a straight line the differential is eliminated(the spider assembly and the truetrack internals are not changing position). Only the drive ring and pinion are moving and are the source of the noise. The proper spacing and centering of the pinion to the ring is crucial or u get noise and chipping or flat out breakage

 

That's what I thought too. I didn't hear any noise at all during my 500 miles of break in though. I guess the shop wants to see if the coast side of the ring gear will break in. The mechanic told me too drive it for a week and see if it changes at all. He didn't take the differential off and inspect the gears.

 

I've read many times that you shouldn't hear any whine at all after a gear install. I've also heard that you might hear some during break in. I honestly don;t know which is true and maybe it depends on brand of gears.

I had Superior gears done and was told by my installer (a Jeep dealer who is very mod friendly) to expect a sklight whine the first 100 miles or so. This was told to me long before I agreed to have them do the work. Sure enough, once it was done, I had a slight whine for about 50 miles then it went away. I have 30K on those gears including many rock crawling adventures. No issues.

Now, your issue is different. If you had no whine during break in but now have it, then something is off on the install. I know several people that had your issue pop up after a successful break in period only to wait too long before the gears get wrecked. Your installer should pull the covers and at least look at the pattern again.