My differential went out and I thought I would do a bit of work, being that it has 200K and I never have. I got a 3.46:1 LSD, put in a new center bearing and flex disc on the drive line, put in a new clutch, throw out bearing, had the fly wheel done, replaced the rear main seal, the oil sending unit, transmission mounts, etc. I put RedLine MTL in the tranny and Amsoil 75W90 in the rear diff. I didn't want to have to go back down there for a while. I now have a noise that I normally would assume to be throw out bearing. (which is why I decided to do the clutch too) When the clutch is out, and the car is in idle, it sounds like the throw out bearing is bad. The next closest sound would be like there was a knock or something in the bottom end of the engine. When I engauge the clutch, the noise goes away.

Thoughts?

Thanks,

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rattling of the gears/bearings in the tranny. I don't know what lube you used in there before, but thicker oil can mask the noises. The knocking you describe can be often heard in any Getrag when the engine is shut off (with the hood open) as the engine comes to a stop. It could possibly be the throwout bearing just touching the pressure plate fingers and bouncing in and out a tad as well.

When the clutch is depressed, the tranny mainshaft stops turning, of course.

If just lightly depressing the clutch pedal an bit(an inch or so, but not enough to disenge the clutch) makes the noise disappear, it is the throwout bouncing until it is held in firm contact with the pressure plate.

I wouldn't lose sleep over it in either case unless it is alarmingly loud.

Bob