Transmission noise

[WoodyDeuce]

Hey all, just curious if anyone has encountered such a noise before. A little background, I drove all day at NJMP Thunderbolt with NASA on Sunday, and the car did fine as usual. However, I noticed a clinking noise on deceleration at low engine speeds in third gear today. The noise does seem to stop if I put the clutch in. Just situationally I’m thinking input shaft bearing or synchro but I’m not a master mechanic so I thought I’d ask the crew. It’s a new rattle so I’m just trying to be prepared.

It’s a little hard to hear but as I lift out of the throttle you can hear a rattle/vibration/whirring? Don’t know how to describe it.

https://youtube.com/shorts/wl9c0kzYrh8?feature=share

[NoHaveMSG]

Does it go away if you rest your hand on the shifter? It is hard to tell in the video but can you tell where the noise is coming from? Directly below the shifter or rearward? Maybe put the seat down and see if it is louder that way. I don't think it is transmission associated, it sounds like it has more to do with backlash in the drive train.

[WoodyDeuce]

It (the noise) can’t be damped out by putting your hand on the shifter. You can make the regular shifter rattles that we’ve all come to love go away by grabbing the shifter and the reverse lockout collar, but the noise is still there. My impression is it’s coming from forward of the shifter, engine bay area. I can’t isolate it any more at this point, and I’m not even completely confident in that being true, you could be righ and it could be aft of the transmission and further back in the driveline, but the gut instinct as I was driving it was that it was forward of me when driving it.

[Ultramaroon]

I hear it. Do you get it in any other gear?

[NoHaveMSG]

I am assuming your car not being stock if you are doing track days. What mods? I know some headers have issues with hitting the undertray. I wonder if the drivetrain backlash is causing it to tap the tray though it sounds like it is more subtle then that. It does sound like it is rotational though. Just thinking out loud

[WoodyDeuce]

Not hearing it in any other gear right now, at least on a kinda short drive. I guess it's possible that I just wasn't able to reproduce it situationally load and engine speed-wise but my initial impression is it's limited to third.

[WoodyDeuce]

Hey, I appreciate the insight! At the very least this would be good to rule out. I do have an aftermarket EL header, and I have had issues with them rattling, but not since I beat on the undertray with a BF'n hammer. But, I'll remove the tray and drive it around a bit to rule that out, good idea, thanks

[WoodyDeuce]

So the noise remains after the undertray is removed unfortunately, and the noise isn't reproducible in other gears, third gear only