Well, at 42,300 miles I drained and filled my diff today. It was even easier than I thought becuase I ordered Amsoil fluid and bought the bottle pump for $12. Works awesome! Even better than previous experience with having room on other cars to pour the bottle right into the filler directly or using a suction pump. The only spill I had was due to putting the end of the hose down a minute to check if the level was getting close.
BUT this was on the drain plug and I'm concerned escpecially since I can't figure out what the heck it is! I'm guessing some kind of metal ring that holds in a seal? I've looked over the exploded view in the service manual and haven't ID it yet. Maybe a trip by the dealer is in order since there is a 5yr/60k powertrain warranty right??
Let me know what you think



What a way to start the week

 

That looks like a piece out of a needle bearing.

 

does the car roll freely? can you push it easily in neutral?

does the diff make any new or weird noises (other than the typical tranny/diff whine)?

 

No. It seems fine. In fact it feels like it rolls just a little easier. I can tell by the way it rolls in neutral at stop signs and lights and how it takes off from a stop. Just enough to be perceptible but it may be my imagination. Definately no problems though. Who knows when that piece broke off. I'm a little nervous of the rest of it coming loose and causing major problems. The used fluid was dark of course but as I tranfered it to another container from the new drain pan you could still see through it pretty easily like dark honey. No big shavings, just the gray paste accumulated on the magnet along with the one big chunk. No noises. If you are scratching your head to figure out what it is too this is a BASE diff by the way.
I'm stopping by the dealer tonight to see what they will do for me before something bad happens.

 

VO(subscribing to find out what it is)

 

Well, I stopped at my dealer last night. I wasn't sure how they would respond or what questions would come up so I just walked in and one of the service writers I recognized from my axle click TSB said can I help you.
I said, yes I need some help. I pulled out the part and just said I changed my diff fluid yesterday and this was on the drain plug magnet. He did not seem surprised at all. He looked at it for a couple of minutes thinking and thinking and we talked about what it definately wasn't. He then said it looks like something that got in during production don't worry about it. I said that I couldn't identifiy it as a diff piece either and stopped to show it to a mechanic. He left to go take it to the shop and talk to a mechanic and said the mechanic said it is definately not part of a gear, seal, bearing, or anything else that is in the rear end. It doesn't belong in there and that is what the magnet is for. Asked me if there were any shavings or other pieces on the plug. I said no just the typical gray paste from all of the microscopic wear and this big piece, that was it. (If I didn't mention before - Fluid was pretty clean too and I dragged a magnet through the drain pan for a few minutes and got nothing.) He said again, don't worry about it. The piece you found obviously got pulled part way through the gears because of how it is crushed but the Z's rear end is very strong and we've never had trouble with any at all.
I work with automotive suppliers every day so I am not shocked by the response or that there could be crap in the case. I can tell that if I had dropped the car off to have it done they would have just filled it back up and I would never know. I also figure I have 13,000 miles left on the powertrain warranty. I could worry about it forever but I'm not going to. For now I'll just consider myself "lucky" in a strange situation. Thinking about it now I also am not going to beg someone to take my car away from me leaving me no way to get to work, tear my car apart, and worry what might go wrong if they don't do a perfect job
The only bad thought I had on the way home is that if it was going to be warranty to pull the rear end and work on it they should want to do that becuase Nissan pays them for warranty work right? I don't really feel like they were avoiding anything but I'm not 100% sure how that kind of stuff is handled.
Anyway I though I should share since I brought it up, sorry for the rambling

 

That was my thought also ---Its not a needle brg piece cuz there are no needle brgs and its too small to be the lock pin. I wouldnt worry about it. The thrashing it took will have no effect on the components, it just tangled with one of the gears

 

Any ways ---needle brg rollers break like glass. NEVER have dents in them. That is not a hardened piece and just bout everything but the roller brg cages is hardened in a Diff.

 

Yeah. The exploded view in the service manual only shows beefy tapered roller bearings with solid races which I've seen while taking apart other trannys and this is not a piece of one of those. Only other pieces in there are gears and seals. I thought maybe not knowing what the seals look like it could have been one of those snap in rubber seals with an inner ring imbedded in it or something to hold it in but I was streching my imagination at that point. I think the dealer is correct at this point.

 

good deal.