If the chattering started after replacing the clutch, check the obvious first.<BR>Sounds like it could be a mis-adjusted clutch<BR>(not fully disengaged when foot off pedal).<P>Lower ratio gears(reverse or granny low) reduce strain of setting into motion from a dead stop, and might explain no shuttering effect while in reverse.<BR>Adjust the clutch pedal first, to allow proper pedal "freeplay"