Originally Posted by bbake250f
I just purchased a 2002 LT and being an X-Dragbike rider I was curious what it would do on a mild burnout. I know that is stupid so save the remarks as I'm just looking for a technical answer and I realize this bike was not designed for this type of abuse. I was mainly curious if the front end would come up or if the rear tire would break loose. I was going about 5 mph, grabbed the clutch, revved to approx 6K rpm and dropped the clutch. Nor did I wheelie or spin the rear wheel. Instead the bike chattered a great bit and accelerated forward. I was listening to my in helmet CD so I wasn't sure if what I thought happened actually did or not. It was later confirmed by my fellow workers that it did in deed make a chatter noise. The bike has approx. 18K miles on it and has been babied up to this point with all the normal maintenance and oil changes. I also just switched all the lubes to fully synthetic. Do you think it was the dry clutch, shaft drive or gear box that made the chatter? I'm kinda worried now that something is wrong and ready to break. Bike seems normal and I haven't tried it since.
How's this for obnoxious: I think everyone is wrong
(yeah, I'm stirrin'
Seriously, I expect the noise was from the transmission, and specifically the shock absorber built into the tranny input shaft. The absorber is designed to prevent MASSIVE shock loading to the drive train (such as, say um, dropping the clutch at 6 grand!). It consists of a heavy coil spring and two sine wave-shaped collars on the input shaft.
The spring is very strong, and in normal operation keeps the two collars tightly engaged with one another, so that power coming in on the first collar passes immediately through the other collar to the tranny intermediate shaft.
When the input shaft receives a big shot, the first collar starts to rotate relative to the second collar, and its sine wave-shaped ramp starts to ride up the face of the opposing ramp on the other collar, forcing the collars to separate against the force of the spring. After the input torque peaks, the spring pushes the two collars back down their respective ramps back into full engagement.
So what's the source of the chatter you heard? If the first collar rotates more than 90 degrees before the torque peaks, its ramp passes over the top of the second collar's next ramp peak, and slams into the second collar's next valley (bang!). Do this with enough suddenly-applied torque, and maintain that torque (like when trying to do a burn out
) and the damper will merrily rise/fall over the ramp peaks several times in succession (bang!bang!bang!bang! ... well, you get the idea).