Gear Cog 35 teeth DRT 4th gear 803-O “4-gear”

for Vespa 125 VN/
M/
50 VL/
B1

90 mm
h 12,5 mm
mid section:
m
reinforced Product description
Faro Basso, Fender Light
THE vintage Vespa icons, without a doubt! Regrettably the few remaining classic Vespa Wideframe models tend to be restored to their former glory, conserved and no longer seeing on the road ! Which is understandable when confronted with a maximum speed of around 65 kph and fragile engine components! Its been fascinating to observe the current technological developments that have been evolving for this scooter type on the German-speaking scooter scene. A reliable motor with adequate amounts of torque (10PS) is now possible. DRT have decided to assist in this with the production of suitable gear cogs.
This
set of output shaft gear cogs
‘DRT 807’ comprises of cogs with 13-13-17-21 teeth respectively and is part of a four-speed gearbox upgrade. This kit enables the original three-speed gearbox included with the Vespa 125 VM/VN/150 VL/VB1 to be upgraded to a four-speed type for an improved exploitation of any extra power available and also a higher maximum speed! This conversion requires mechanical knowledge to be properly and safely installed. The original output shaft from the VB1M engine can still be used, along with the input shaft. The gear selector and cruciform from the GS 150 should be used to replace the VB1M items.
The corresponding
gear cog sizes
and their possible combination possibilities are listed below. With use of the original first gear, the rest of the gear cogs originate from the Vespa PX Lusso models engine. The first and fourth gear cogs will require slight modification however, with the first gear having its centre section machined to fit and the fourth requires narrowing. The suitable
DRT gear cogs
can be used as well of course.
DRT also produce high quality
primary drive cogs
with 65 or 67 teeth, which have the effect of altering the overall gear ratio. This can be achieved without replacing the standard gear cog ratios and is fully compatible with otherwise original gearbox set ups.
Conclusion
: If you want the option of four gears on your Faro Basso, you will need to invest a lot of time and work!

Do not forget to order the gear selector and cruciform from the GS to complete this project. You can then experiment with possible gear ratios, starting with a primary drive cog that has 65 cog teeth.

The following gear cog combinations are possible, the DRT recommendations for use with a 65 tooth primary drive cog, are marked in red.

Gear
Output Shaft
DRT Gear Cog
Name
Article Number
Note
1
Gear
13 th
56 th
original (
114,93mm, 3 Gear VB1m)
modifications necessary
2
Gear
13 th
42 th
PX/PX Lusso
15280500
42 th
DRT 801
40438010
41 th
DRT 270
40432700
40 th
DRT 270/A
4043270A
3
Gear
17 th
38 th
PX Lusso
88130000
38 th
DRT 802
40438020
37 th
DRT 281
40432810
36 th
DRT 282
40432820
4
Gear
21 th
37 th
DRT 290
40432900
modifications necessary
36 th
PX Lusso
22322900
modifications necessary
36 th
DRT 291
40432910
modifications necessary
36 th
DRT 291-O
4043291F
35 th
PX Lusso
88120000
modifications necessary
35 th
DRT 803
40438030
modifications necessary
35 th
DRT 803-O
4043803F
34 th
DRT 292
40432920
modifications necessary
33 th
DRT 305
4043305K
modifications necessary

OEM numbers (for comparisons):
(PIAGGIO)
IG O4^ z35.811- OLDf1 (807) / 8000000035004 (DRT)