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Transmission Rattle/Clunk/Loose Metal Sound : Update - Maybe Rear Diff?

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Took the 510 on its longest journey yet- up to Limerock Park (1.5 hrs or so) got a to take a couple parade laps - pictures latter when they are up...


Any way ran into an issue on the way home...


The car drives fine as if there is no problem - no issues getting it in gear, no odd noises, other then the whine in 4th and 5th, but its done that since I bought it and
I always figured it was because there was nothing to insulate the sound (no carpet or anything inside the car)


I believe it is a 280zx 5spd


What it is doing is that when shifting or in neutral with the clutch in it will get a rattle or clank, almost as if there is a piece of metal in there that only gets picked up and bounced around sometimes. but it only happens when the clutch is disengaged i.e. pedal to the floor, seemed to be more prevalent in the 2nd to 3rd shifts but had it happen in the 1st to 2nd and 3rd to 4th.


Just changed the transmission fluid last week. I had the speedo gear pop out of the transmission housing- no damage to the gear, minimal driving while it emptied ( 1 shift, and maybe a mile) Replaced with Redline MT-90 transmission gear oil - yellow metal safe - felt like there were smoother shifts after changing.


When I drained the remaining transmission fluid it came out surprisingly clear with very few metal shavings on the magnet.


Any help or insights appreciated- been searching, still searching, but I have a pretty limited knowledge of transmission.




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With the clutch pedal down to the floor there should be nothing moving in the transmission... so this is outside of it. Probably the release bearing (which is under load with the pedal down) or possibly a damaged pressure plate... even the clutch disc.

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That is a possibility - ill have to drive it again tomorrow- part of me remembers it still klunking or what ever for a second after re engaging the clutch-


Any way to further diagnose it?

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Been a while- got to drive it around a bit last night to try and recreate it... unfortunately cant get it to recreate- but... there is quite a loud whirring noise coming from what sounds like the back end and not the transmission. Possibly the rear diff? Took a passenger and they pointed out that is is definitely coming from behind the transmission. Happens in 3-4-5th no noise under engine braking or accelerating loads- but when your "coasting?" or just barely on the gas it is quite loud. Also happens in any gear when you are coasting and clutch in.


Just recently replaced the fluid in the diff and it definitely wasnt clean and there was quite a bit of gunk around the magnetic drain plug... 

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So definitely the rear diff- drained the gear oil again and the magnet was full of metal- again- after only 100 miles or so of use.


Pulled the diff and sure enough the gear coming off the driveshaft has seen better days


So I am going to use this as an excuse to upgrade to an LSD - anyone got one?











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Yo has anyone else dealt with this?


My dimes 240zx 5 speed is rattling like a small jar with a couple BBs in it.. it tends to go away when I push down on the shifter stick and there is no sound while driving just when its out of gear.. 


what do y'all think i should check?

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Probably need to open up the tranny to inspect it.

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If just idling in neutral it's probably the shifter as you explained.

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