Need transmission problem diagnosis..., Or best guess Options

[Porsche Rescue]

Started my '70 tail shifter this morning, attempted to engage reverse and heardf/felt a horrible grind (kind of like the clutch pedal was not depressed, but it was). Quickly returned to neutral and tried again. I engaged reverse OK and backed out of the garage. But I heard a grinding/growling noise while moving and felt the sensation of something restricting movement (like brake on, but it wasnt'). Moved it back and forth in the driveway in all gears. It makes the same noise in all 5 forward gears as soon as I release the clutch. Reverse now seems almost OK.

Where do I start? Could it be a linkage issue (the front two bushings were new a few months ago)? It shifts smoothly when clutch pedal is depressed. Is something broken in the tranny? All opinions welcome.

[Katmanken]

I'm gonna put on my Patent Law and my engineering hats and look at this several different and possably contradictory ways....

When the clutch is slipping and the rear wheels are locked, the tranny drivetrain will rotate a little to take up slop- It's called called windup. Windup in this system happens through all the components from the clutch disk to the wheels.

I'd replace the flywheel bearing for sure. It's cheap and is rotating around the stopped mainshaft.

Which brings up several other points.

Have you measured the flywheel for endplay? When a system loads, things move. I'd check to see if the endplay is OK because if it's not, the flywheel/crank could move and contact things and make noise...

And, are the clutch disk and pressure plate flat? ..... I'd check that because if the clutch disk has a thicker section (lump) and/or the pressure plate has a broken spring and can't push uniformly on the clutch disk, you might get uneven slipping as the disk slips relative to the pressure plate, and then we enter the world of vibrating systems. If the clutch system isn't flat, you could be sending a rotational oscillation (ie a small oscillating clockwise and counter clockwise rotation motion) which will wind up the system and then unwind it. That would rotate some tranny and cv bearings back and forth.

If I understand correctly, when the tranny is in gear and the clutch pedal is fully released, the car should move and the growl should happen. At that point, the flywheel bushing is fixed (non rotating) relative to the main shaft, the clutch is locked relative to the flywheel and main shaft, the tranny pinion shaft and differential start to move and noise happens. At that point, the flywheel bushing and the clutch should be considered non-noise making elements and out of the picture- unless we have some slippage. Is the clutch disk burned or glazed???

I keep coming back to the pinion shaft/differential because it becomes rotatably engaged when two things happen- 1. you are in gear, and two, the engine is driving the wheels. If you look at it from the point of letting off the gas in a moving car with a gear engaged, the rear wheels load the tranny and try to spin the engine .....- wich means the pinion shaft/differential is spinning.......