Testastretta belt tension without a Mathesis

Some notes on setting belt tension.

Beginning with the Testastretta motor, Ducati now requires that belt tension be set by measuring the belt's vibrating frequency when plucked. Normally this requires multi-billion dollar equipment, but after much research (thanks to ducati.ms), I was able to set tension with nothing more than a microphone and a notebook computer.


A simple PC microphone should be sufficient if you can eliminate all extraneous sounds from your garage. I can't do that, but luckily I have a cheap Shure dynamic mic. While condenser mics are more sensitive, they cost a mint, and more importantly, they will pick up every aural minutia--NOT GOOD if you are trying to isolate the sound of the belt. A uni-directional dynamic mic is better if you have ambient noise like me.

I used a freeware program called Audacity. For the vertical head, the belt should be plucked on the part between the static (non-adjustable) tension pulley and the drive pulley. For the horizontal head, it should be plucked on the part between the mobile (adjustable) tension pulley and the drive pulley. Set the head in question to TDC on the compression stroke (EXTREMELY IMPORTANT), mic the belt, start recording in Audacity, and pluck a few times. Use the spectrum analyzer, keep repeating the process until the correct frequency is achieved. The factory spec is 110 hz, which corresponds to A on a bass guitar.