PM Tuning Gear Up Kit Piaggio / Gilera / Italjet 125/180cc Primary Straight Cut 14/29
Suitable For Most 172cc upgrade kits
The advantage in fitting primary gears as apposed to secondary gears … no need to to use a hydraulic press and you do not need to remove the rear wheel and associated parts.
So why are PM Tuning producing straight cut gears for these models now ?
Well, there are a few reasons why, but the main reason is because straight gears don’t produce any thrust loads as power is transferred through a pair of helical-cut gears, an axial thrust load (sideways force) is created on each gear due to the angle of the teeth. This thrust load is harmful to the bearings in the transmission for a given load. As power and TQ increase with modifying and tuning so does the side load, putting more pressure/ friction onto the bearings shims and casings .The upshot to this reduced pressure and frictional losses will be around 5% gain in efficiency.
By installing an aftermarket straight cut gear set into a case that came from the factory with helical gears, it is possible to drastically increase the load capacity of the transmission without losing the reliability of the original bearing and casing configuration.
The only down side to straight cut gears (if that bothers you) is an increase in transmission noise that will sound similar to a supercharge whine .
***please note this gear only fits later rolling nut engine***