I recently installed a Exedy stage 1 clutch, Fidanza lighweight flywheel, and LSD. I also installed a RB engine torque brace shortly afterwards and that is about when the problem started. I'm thinking something may have given way in the Tranny, possible the input shaft bearings?. Check out the video, the rattling occurs after I rev the engine and, as you will hear, will go away when I press the clutch pedal with just my hand.
http://www.youtube.com/watch?v=jFpbRwqzJlA

Symptoms:
Car is driveable.
Tranny shifts smooth and drives well in all gears.
No rattling at startup.
Noise starts to occur when I rev the engine while in nuetral or when in gear at low rpms.
Rattling stops if I slightly touch on the clutch pedal, and will completely go away if I pump the clutch pedal (sometimes), or if I pop the clutch a little when taking off.

What I have done so far:
I dropped the tranny and inspected the clutch and flywheel, they looked fine.
Installed a new pilot bearing and a different t/o bearing again.
Bleed the clutch master cylinder.
Manually pulled the clutch fork back to make sure the t/o bearing was disengaging completely.
Adjusted the clutch pedal free play messing around with various setups.
Motor mounts are good, tranny mounts are good, nothing wrong with the driveshaft.

I'm getting ready to drop the tranny again to swap in another one to test it but just wanted to get some feedback.
Thanks!!!!!!!!

 

Sounds like a seriously messed up main bearing. I had one wear out on me, but it was a much quieter droning sound while in neutral. The fact that the sounds goes away with the clutch pedal in should tell you that the problem is in the tranny.

 

So, if the main bearing failed would there be traces of metal in the tranny fluid?

 

Yeah, mine had pieces of the bearing.

 

Thanks for the info, I'll drain the tranny this weekend and see what it looks like.
I need some sort of confirmation before I take the tranny in for repair.

 

Sounds like a loose flywheel to me. Tighten that **** before the flywheel slices off your legs!!!!

 

I have heard of someone else having a similar noise just after they installed a clutch and flywheel. It turned out to be that he forgot to tighten the flywheel to counterweight bolts. I would most definately find the problem before you drive the car anywhere.

 

It sounds bearing related.I am thinking though that it may be a throwout..it sounds like it is sloppin at the Shaft and hittin the Clutch,But when you hit the Clutch,it puts pressure on the Throwout and it Makes Good contact with the Clutch.(that is My Far fetched Guess,But you definitely Need to drop it again..Another Guess is that the Pressure plate is not Bolted down,and when the clutch is Pressed the pressure makes the sound go away.