WOFÜR
Shoulder rings serve to compensate the axial play between the gears. The distance between the gearwheels is essential for a clean shifting. The narrower the play, the less the gears can slip sideways. The gear change becomes more precise as the shift cross now engages exactly in the middle of the gear wheel and does not push it away first. It is therefore worthwhile to measure the gear precisely.
HOW MOVEMENT
The backlash specified by Piaggio is 0.15-0.40mm. It is determined with a feeler gauge between the gear wheel and the shoulder ring.
UNTERSCHIEDE
The original shoulder rings are available in two versions:
OLDIES
The thick version of the shoulder rings for Largeframe Vespas before 1984 is no longer available from Piaggio. Thanks to bgm PRO, the matching shoulder rings in the 2mm to 2.50mm range are now finally available again for these gears.
As a deviation from the original, they have 4 noses for locking, as on the more stable Vespa PX Lusso variant. The new design therefore no longer allows the individual nose to be knocked off.
TIP: The exact determination of the clearance between the gearwheels is only possible with a feeler gauge (see accessories). Don't forget a new BGM Pro shift cross and the transmission oil.