Drivetrain Noise - Help

[FugitiveFromJustice]

So heres the problem:

There is a mechanical grinding/crunching noise in all gears at certain rpm. Only happens under load, does not happen when in gear with no throttle. Happens at:

1st gear : ~1800-2300 (hard to tell as its not very loud, only happens under med load)

2nd gear : 1400-1900

3rd gear : 900-1500

4th gear : <1500

5th gear : <1500

Car is a 97 gts-t, with standard box. Upgraded clutch.

Does not change with respect to oil temps. Noise is louder in higher gears, and when under a greater load. Spoke to a few mechanics and each has their opinions. Drive shaft bearing, gearbox on its way out, a vibrating plate or something somewhere along the exhaust, or even the clutch springs due to their stiffness under a certain load. Anyone had similar symptoms on the r33?

Any help appreciated. Cheers, Rob

[RB-20-OB]

So heres the problem:

There is a mechanical grinding/crunching noise in all gears at certain rpm. Only happens under load, does not happen when in gear with no throttle. Happens at:

1st gear : ~1800-2300 (hard to tell as its not very loud, only happens under med load)

2nd gear : 1400-1900

3rd gear : 900-1500

4th gear : <1500

5th gear : <1500

Car is a 97 gts-t, with standard box. Upgraded clutch.

Does not change with respect to oil temps. Noise is louder in higher gears, and when under a greater load. Spoke to a few mechanics and each has their opinions. Drive shaft bearing, gearbox on its way out, a vibrating plate or something somewhere along the exhaust, or even the cutch springs due to their stiffness under a certain load. Anyone had similar symptoms on the r33?

Any help appreciated. Cheers, Rob

drain the oil from the box, the plug is magnetic and picks up any metal in the gearbox.

check that first, if nothing there check type of clutch or even noisey uni joints. from what you have described it sounds like the internals of the gearbox that are the problem.

[FugitiveFromJustice]

Ok so if any one is interested, the problem seems to be the clutch spring stiffness.

At certain loads and rotational speed (read: throttle position and engine rpm) the springs inside the clutch rattle and vibrate.

The sound is terrible, its a mix of harsh vibrations and a brutal mechanical grinding noise.

As i was told, 'you can go round australia' with the problem as it is not detremental to the drivetrain. Best news is that is it not getting worse, but will only be fully diagnosed if and when the clutch will be replaced.

[Birds]

The clutch thing is a bit of a hit and miss in my opinion, have a feeling this is a mainshaft bearing that doesn't like a certain RPM. Gearbox reco...but by all means test the clutch first