Hey all. I have a K24 swapped S2K I've been driving without major issues for about 7k miles till now. All fluids including trans and differential were replaced while building the car.

Seemingly out of nowhere while driving home from work I got a nasty clunking sound coming from what I thought was the differential at first.

After getting home I put the car on Jack stands, I
put it in gear and found the sound seemed to be actually coming from the transmission. The car has 99k miles on it and the vin on the transmission matches the cars, so I know it's the original transmission. The fluid looked okay to me in both the trans and differential (which I checked just in case).

Here's a couple videos of the noise. It occurs any time the driveshaft is moving including in neutral and doesn't matter if I have the clutch in or not. I can definitely feel the problem from inside the car it feels terrible and seems worse at lower speeds (under 40 MPH or so).

Under the car:
https://youtube.com/shorts/7PhWS4TSVTA?si=BGjrz8dCFd47AYqt

Inside the car:

https://youtube.com/shorts/qzVYqtrMwnY?si=KaFfzfmzbinlPG9-

If I move the driveshaft in neutral with my hand I can actually feel something binding on it about once a turn.

Every gear works fine and shifts smoothly. Strange issue to me. I'm suspicious of the trans output shaft bearing but it sounds so much worse than any bearing failure I've ever heard. Any assistance is greatly appreciated

 

Is the fork fully seated?

 

No idea if the shift forks are seated, but I assume so as the car shifts into every gear smoothly. It's just this weird knocking/vibration.

I disconnected the driveshaft today and spun the output shaft of the trans in neutral. It's definitely the transmission. I'm thinking one of the bearings in the tail shaft side of the trans is cooked.

Going to order an AP2 trans to replace with and update if that fixes the issue.

 

My pilot bearing was going out and I think towards the end of it's life it was making similar noises. Either way, it looks like you're going to have to drop the transmission.

I'm hoping it's just your pilot or a throwout bearing.

 

So I dropped the old transmission this past weekend and sure enough something is bad in the transmission. I sourced an AP2 transmission, swapped the AP1 driveshaft flange over and installed it.

Issues are gone, but I want to tear down my AP1 trans to see if I can't figure out what happened to it and rebuild it.

Pics below of old trans dropped and installing the new AP2 trans.

 

Thanks for the update! Good luck with the new (used) transmission.

 

Remove the large Allen bolt on the bell housing, you can see inside the transmission through there and there's a magnet below it that will pick up any chunks.