for Vespa 125 GT/ GTR/ Super/ TS/ 150 GL/ Sprint/ V/ Super/ 160 GS/ 180 SS/ 180 Rally/ P80-150X/ PX80-150 E/ Lusso/ ’98/ MY/ ’11/ Cosa 125-150/ T5 with repair kit primary DRT Product description 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. 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 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 OEM numbers (for comparisons): 8000000028792 – a02879 (previous: PRk VelPX 229 z6 (DRT)