I posted this in the FI section but I figured I would have better luck here.

I started getting this very loud metal on metal rubbing sound in fifth gear only. I pulled the tranny a couple of weeks ago to replace the clutch. Threw it back on and everything was fine until I was having problems with the clutch disengaging and when my axle popped out and got stripped I decided to pull it and see what was the issue. I realized I had lost most of my tranny fluid so I took the transmission apart and I had to replace my 5th gear syncros, hub and taper ring. I put everything back together and put it back in. When I was bleeding the clutch I realized the master cylinder was leaking and that was the reason the clutch was not disengaging properly. I took it out for a road test and gears shift like butter. I put it in 5th gear and as soon as the clutch engages I hear the sound and its even louder when decelerating/engine braking. I took it back out, took it apart and everything looked good with no shavings at all or any sign of rubbing. The clutch looked fine also. So I just finished putting it back together and ITS STILL THERE! Here is a video with the car on jackstands and the tranny in 5th gear. It does not do it in any other gear. Any help is appreciated.

 

Pics or measurements of 5th gear?

 

I did not replace the actual gear, just the hub, syncros and ring. It is a gsr tranny.

Actually, I have I might have put in the "other" mainshaft instead of mine. I took a mainshaft from a buddy that still had good 5th gear hardware but now that I think about it I might have put the whole shaft in since I had them side by side.

Wrong 5th gear on the mainshaft would make that sound?