Piaggio Retaining Ring Ø48 x 1.5 mm
Matching retaining ring for the original transmission main shaft
The original Piaggio retaining ring, measuring Ø48 x 1.5 mm, secures the transmission components on the main shaft of the Vespa PK XL/XL2, PX, T5, and Cosa. Its key feature is its thin wall thickness of just 1.5 mm.
Standard retaining rings available on the market may be too thick for the narrow groove of the original Piaggio main shaft. This ring, however, matches the specified dimensions and fits securely into the original groove—without the need for grinding, reworking, or modification.
Piaggio
Ø48 mm
1.5 mm thick
for transmission main shaft
No reworking required
Advantages and Features
Original Piaggio design
Outer diameter or nominal size: Ø48 mm
Only 1.5 mm thick
Designed to fit the keyway of the original main transmission shaft
Fits without sanding or other modifications
For Vespa PK XL/XL2, PX, T5, and Cosa
Corresponds to Piaggio part numbers 009101, 9101, S.9101, and S9101
Why the 1.5 mm thickness is crucial
A retaining ring can only fulfill its function if it sits completely and flush within the intended groove. If the ring is too thick, it cannot be inserted deep enough or will protrude from the sides of the groove.
For the original Piaggio main shaft, the correct thickness of 1.5 mm is therefore essential. The Piaggio ring fits into the existing groove without requiring any additional machining of the component.
Original dimensions instead of an adapted standard ring
Precise fit: The ring snaps fully into the original groove
No rework: No need to grind down a standard ring that is too thick
Secure fit: The transmission components are held axially in their intended positions
Original geometry: The main shaft and groove do not need to be modified
Function of the Seeger ring
The retaining ring sits in a circumferential groove on the transmission main shaft. There, it limits the axial movement of the transmission components mounted on the shaft.
Although the ring is small and unassuming, it is one of the safety-critical components of the gearbox assembly. A damaged, deformed, or incompletely engaged ring cannot reliably ensure the intended axial retention.
Do not use a standard retaining ring that is too thick
It is not just the diameter that matters. The ring thickness must also match the groove on the main shaft.
Required thickness: 1.5 mm
Rings that are too thick cannot engage fully in the groove
Do not adjust the retaining ring by grinding or bending it
If the groove is damaged, the main shaft must be inspected
After installation, check for a secure fit all the way around
Compatible vehicle models
Vespa PK XL
Vespa PK XL2
Vespa PX
Vespa T5
Vespa Cosa
The key feature is the built-in transmission main shaft, which has a groove designed for a Ø48 x 1.5-mm retaining ring.
OEM Numbers
The following Piaggio part numbers are provided for reference purposes only:
Piaggio 009101
Piaggio 9101
Piaggio S.9101
Piaggio S9101
Technical Specifications
| Manufacturer |
Piaggio |
| Component |
Retaining Ring / Lock Ring |
| Nominal diameter |
Ø48 mm |
| Material thickness |
1.5 mm |
| Installation location |
Transmission main shaft |
| Application |
Axial retention of transmission components |
| Models |
Vespa PK XL/XL2, PX, T5, and Cosa |
| Special Feature |
Proper thickness for the original groove on the Piaggio main shaft |
| OEM Equivalent Numbers |
009101, 9101, S.9101, S9101 |
Contents
1x Piaggio retaining ring Ø48 x 1.5 mm
Check before installation
Thoroughly clean the groove on the main shaft
Inspect the groove for damage, chips, or deformation
Check the retaining ring for damage and permanent expansion
Compare the dimensions (Ø48 x 1.5 mm) with those of the removed component
After installation, check for a complete, all-around fit
Installation Instructions
Use suitable circlip pliers
Spread the ring only as far as necessary for installation
Insert the circlip fully into the groove
Check for a proper fit around the entire circumference
Do not reuse deformed or damaged retaining rings
Check the free movement and axial position of the transmission components
Conclusion
The original Piaggio retaining ring (Ø48 x 1.5 mm) has exactly the thin wall thickness required for the retaining groove of the corresponding transmission main shafts.
This ensures that the ring fits completely and securely in the groove without having to grind down a standard retaining ring that is too thick or rework the main shaft. Especially for a component that secures the axial position of the transmission components, the correct original dimension is crucial.
FAQ
The retaining ring is installed on the main gear shaft and holds the gear components mounted there axially in their intended positions.
The groove on the original main shaft is designed for a 1.5 mm thick retaining ring. A thicker ring may not engage fully and therefore may not secure the components correctly.
Only if the diameter, ring thickness, and shape exactly match the Piaggio specification. Many standard retaining rings are thicker and therefore do not fit cleanly into the original groove.
This is not recommended. Grinding can alter the geometry, strength, and surface condition. It makes more sense to use the correctly sized ring with a thickness of 1.5 mm.
The ring is used with the corresponding main drive shafts on the Vespa PK XL, PK XL2, PX, T5, and Cosa.
A deformed, damaged, or permanently expanded ring must not be reused. During a transmission overhaul, it is recommended to inspect it carefully and, if in doubt, replace it.
The ring must sit completely within the groove along its entire circumference. It must not be tilted or protrude from the groove at any point.
DE | €
