Join Date: Aug 2006
Location: Chesapeake, VA, USA
Here's my theory from other machines and my own experiments with non factory tire diameters. The cluck is driveline backlash. At lower speeds there's not enough load plus what I suspect is more gear lash in 1st, 2nd and 3rd gears anyway. So as soon as you pull the clutch in the lower gears at lower speeds everything is allowed to go slack in the entire driveline. Grab the next gear, release the clutch and all that slack is taken up at once and cluck happens. Without the clutch, the driveline is virtually always under load so no opportunity for cluck. As long as you hit the engine rpm/gear rotation sweet spot everytime, up and down shifts are fine clutchless. Missing the sweet spot could have dire consequences.