AnvilZ

I noticed when I disassembled the transmission that there was a shim on the larger main input shaft but not the smaller counter shaft. It does look like the transmission may have been rebuilt before, if the shim was not replaced on the countershaft could that have caused premature wear and failure?

EuroDat, thanks for the feedback, that makes sense about the input shaft being held in by the circlip. The main shaft is not moving at all so I assume my adapter plate bearings are still in tact. Out of curiosity did the 280Z come with the FS5W71A transmission as well or was that only on the 2000 Roadster? Maybe this is a typo on drivetrain.com? Their website shows that transmission in the 280Z/ZX among others: If you are able to find the bearing part numbers that would be very helpful, I will get to work on removing that needle bearing in the meantime and post a picture of the condition once I have it.

@Zed Head I was wondering about that, I included it in the video because it didn't seem right especially since that allows the constant mesh gears to become slightly misaligned. While we wait for some feedback from the others you tagged do you have any insight into my second question around the FS5W71A kit for the 280Z and whether that will work as a rebuild kit for my transmission? Assuming it is a bearing issue I would think it is a good time to replace all the bearings in case any of the others are close to going out. I could get a rebuild kit on order in the meantime.

@Zed Head I drained the original fluid a while back and didn't pay much attention to it, now I wish I had. I did replace it with Redline MT-90 during the rebuild and when I drained that yesterday I didnt see any metal shavings or chunks in that or on the magnetic drain plug. Although I have only put a few miles on the car due to the issue with the transmission since I got it running again. @Mark Maras good question, I did not check that before pulling the transmission. Just got it torn down though, here is a video with it in 3rd gear. No chipped teeth or issues with the synchros that I can see on visual inspection but I am no expert. IMG_6357.MOV

From what I can tell it is about the same under acceleration and deceleration. I had also considered that maybe it was something to do with the harmonics of the drivetrain, maybe something in the propeller shaft/diff/half shafts but it stops as soon as I shift to second or fourth.

Sorry I see how that is confusing, I meant to say that it is continual throughout 3rd gear at any speed. The frequency is definitely speed dependent though, it would increase with RPM. It does not clunk with the clutch pedal down in 3rd. I don't know how to describe it other than a clunk, maybe there is a bit of grinding going on as well that I cannot hear over the engine noise. Definitely not a whining sound though.

I will check that, thanks for the suggestion. Would that manifest more when shifting into 3rd or once the transmission is already in gear? Or both? To add some clarification that clunking sound is continual while in third regardless of speed from what I can tell. Actually shifting into 3rd seems pretty smooth, just as soon as I let out the clutch it starts clunking.

Hi all, new to the forum so hopefully I am posting in the correct location but hoping someone can help with a transmission issue. I am nearing the end of a complete teardown and rebuild of my 5/71 240Z with the Monkey motion F4W71A trans. Finally got the car mostly back together and running, but I am getting an awful clunking sound from what sounds like the transmission that only happens in 3rd gear. 1st, 2nd and 4th all seem relatively quiet, I have maybe noticed a slight noise in reverse. Maybe not surprising considering the car has been sitting for the better part of 15 years prior to the rebuild. Anyway, I do not notice any grinding or trouble shifting for any of the gears, or any noise or vibration in neutral. Assume this is maybe a bad bearing or potentially a problem with the gear itself? Anyone experienced a similar issue? I was not able to get a good sound clip, however I did pull the transmission yesterday and plan on rebuilding it myself, which brings me to my other question on the rebuild kits. It sounds like the parts are expensive/hard to come by for the A type boxes, I did find a bearing kit (https://www.datsunparts.com/1049) that says it is for both the F4W71A AND FS5W71A that was apparently the 5 speed used in the 2000 Roadster? Is this the same FS5W71A used in the 280Z, and if so would a kit like the one here https://www.drivetrain.com/nissan-fs5w71-synchro-kit-07-nissan-fs5w71-synchro-kit-dts-bk104 work for the F4W71A? If that is the case the parts seem readily available and fairly cheap from drivetrain.com, but maybe I am missing something.