Primary Driven Gear 65 teeth,
input shaft, DRT for Vespa
125 GT/GTR/Super/TS/150 GL
fits clutch cog 20/21/22 teeth
with repair kit primary DRT
The DRT Primary Gear with 65 teeth was developed to lengthen transmissions of large frame Vespas built from 1960 on up to 125/150 cc PX models. The DRT gear has a larger diameter than the PX200 primary 65, and matches the original. It's a perfect fit for all clutch gears with 20/21/22 teeth, though not with the PX200 clutch with 23 teeth.
SIP-TIP: Tried and tested: the combination of longer 4th gear w/ 33 teeth and short primary (65-20) or 4th gear DRT 36 teeth with a 21 or 22 toothed clutch gear.
Feasible Transmission Ratio
65-22=2.95 65-21=3.10 65-20=3.25 22x65x25x45=5.30
37-21=5.20 37-21=5.45 37-20=5.72 22x65x25x44=5.20
36-21=5.06 36-21=5.30 36-20=5.57 20x65x27x43=5.17
35-21=4.92 35-21=5.16 35-20=5.40 20x65x27x42=5.05
34-21=4.80 34-21=5.00 34-20=5.26
33-21=4.65 33-21=4.86 33-20=5.10
OEM Numbers (for the purpose of comparison)
IPclel z65 229k (PX125-150) (DRT)