Differential fluid level question

[dfw81shark]

Yet another differential thread. Sorry guys, but I have a few quick questions.

Many of you know had my dana 44 rebuilt with 3.54 gears late last year. I filled it with Castrol Hypoy C Gear Oil 80W-90 "Limited Slip Performance." I also put limited slip additive of whatever autozone carried (forgot the brand). If I remember right, I put in 3 quarts of the Castrol and the whole little bottle of additive. I did this when the diff was still out of the car.

I have been having some issues, which I will detail below, and what I plan to do below that:

After doing 70mph on the highway for a while and then doing 30-40ish, the rear likes to sing to me. I can live with this if it is supposed to make that noise. It doesn't sound right though.

The upper left bolt on the rear of the diff is leaking fluid very slightly, and at speed with the aerodynamic effect, over a month or so, it has created a very very nasty dirty backend of my car.

I have some teflon tape that I am going to use to reseal that bolt unless someone objects that it may screw something up.

As far as the fluid goes, I was planning to drain out the old and put in the real deal GM stuff that everyone keeps talking about. It may or may not make the noise go away, but it will make me feel better that I changed it on my brand new parts in case there are some shavings or crap left in there.

If anyone has an advice on the above stuff, I'd appreciate it. Now for my real question:

I pulled the drain plug and fluid came spilling out. This doesn't seem correct to me, because of the searches I've done other people say siphon the old out of the hole and refill till it reaches the top. Did I have too much in there? A bunch came out. I pulled the plug after driving 3 hours ago. I figure that would be enough time to drain everything to the bottom. How much should I expect to put back in? Would that be causing my singing?

 

[like2drive]

Maybe a Chilton or Hayes is in your future?

Well, my 2 cents worth.
Yeah, you way over did it on the fill-up my friend. I don't know what it could hurt except the gaskets, seals, or anything that could be damaged by pressure...maybe. There is a horizontal plug about half way down the back of the differential where you "fill 'er up". With the unit in place, you're supposed to suck all the old oil out as best you can, and then put the new oil back in to the level that it starts to leak out of the plug hole. This is assuming you are on level ground/garage. I always get the GM stuff from the dealer, its only 5 or 6 oz as I recall, and put that in about half way through the job. Alternatively, you could put that in first, then the 80-90.
My rear end has always been singing, ...and the one in the car too! The best guy I could find at the time said to keep driving it, because even if he reb uilt it, it could still sing. That was probably 10,000 miles ago...nothings changed there. I'd suggest getting a Repair manual that will tell you a lot of these things as well as the capacities. good luck, jim

 

[dfw81shark]

Maybe a Chilton or Hayes is in your future?


I have the Haynes manual. Those guys are usually pretty good about their books (I've had quite a few), but whoever wrote this Corvette book was smoking crack. Not to mention they don't talk about the Dana44. They assume you have the GM one from the pictures. And in the capacities section, they just tell you what to use, not how much. Now I know for sure how much to use. Thanks!