Primary Driven Gear 65 teeth DRT input shaft

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 clutchgear.

Feasible Transmission Ratio

PX/T5/Cosa:                                                                                 Oldies:

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