FINAL DRIVE SHAFT • 133mm • 20-SPLINE

FOR QMB139 / 139QMB 50cc 4-STROKE SCOOTER ENGINES

Restore smooth, reliable power transfer to your rear wheel with this replacement rear axle, also known as the output shaft or final drive shaft, for QMB139-based 50cc 4-stroke scooter engines. Precision machined for proper gear engagement, this shaft is designed to replace worn, bent, or damaged OEM output shafts found in many Chinese scooters.

This shaft features 20 splines on both ends for secure engagement with the final drive gears and rear wheel hub.

• Brand New Replacement Rear Axle / Output Shaft
• Precision Machined Steel Construction
• Direct Replacement for Many QMB139 Engines
• 20 Splines on Both Ends
• Precision Ground Bearing Surfaces
• Designed for Smooth Power Transfer
• OEM-Style Replacement
• Excellent for Engine or Transmission Rebuilds
• High Strength Steel Construction
• Durable Heat-Treated Finish
• Restores Proper Final Drive Operation

✔ Rear Output Shaft (Final Drive Shaft)

Engine Type

• QMB139 / 139QMB
• Air-Cooled
• Single Cylinder
• 4-Stroke

Overall Length

• 133mm

Splines

• 20 Splines (Both Ends)

Center Shaft Diameter

• 27mm

Smooth Bearing Surface

• 17mm

Thread Diameter

• 16mm

Material

• Heat-Treated Steel

SKU

• 151-55

✔ Restores Proper Final Drive Operation

✔ Eliminates Worn or Damaged Splines

✔ Smooth Power Transfer

✔ Precision Gear Engagement

✔ High Strength Construction

✔ Long Service Life

✔ Ideal for Transmission Rebuilds

✔ OEM-Style Fit and Function

Designed for many engines including:

• 139QMA
• 139QMB
• 1P39QMB
• 1P39QMA-2
• YN139QMB
• JJ1P39QMB
• 139FMA-2
• BD1P39QMB
• BN139QMB
• 147QMD
• Most Other QMA Engine Variants
• Most Other QMB Engine Variants

This shaft is commonly found in many Chinese-built 50cc 4-stroke scooters equipped with a 139QMB / QMB139 engine, including models from:

TaoTao

• ATM50-A1
• ATM50-A1 Pony
• ATM50-A1 Speedy
• Thunder 50
• Racer 50
• Lancer 50
• New Speedy
• VIP 50
• Quantum 50

Wolf Brand Scooters

• Islander
• Rugby
• Jet II
• Lucky
• Blaze 50 (QMB139 models)

Ice Bear

• Rocket 50
• Vision 50
• Maddog 50 (QMB139 versions)
• PST50 Models

Jonway

• YY50QT-6
• YY50QT-10
• YY50QT-21
• Other QMB139 Models

Roketa

• Maui 50
• Sicily 50
• Bahama 50
• Fiji 50

Tank Sports

• Urban Touring 50
• Racer 50
• Vision 50
• Touring Deluxe

Peace Sports

• Sports 50
• Renegade 50
• TPGS Series

BMS

• Heritage 50
• Roma 50
• Milano 50

Bintelli

• Breeze
• Sprint
• Scorch
• Bolt
• Beast (QMB139 models)

ZNEN

• Many 50cc QMB139 Scooters

SSR Motorsports

• 50cc QMB139 Scooters

Chicago Scooter Company

• Go
• Go MAX
• Bella Classic 50
• Nitro Sport 50
• Pug 50

Schwinn

• Hope
• Newport
• Valo 50 (QMB139 models)

Also Fits Many Other Brands Including

• Dongfang
• JMStar
• SUNL
• Eagle
• NST
• Puma
• Redcat
• Kazuma
• Lifan (QMB139 Models)
• Gator
• Baja
• Xingyue
• Flyscooters
• Keeway (QMB139 models)
• CPI (some models)
• Numerous Chinese scooters utilizing the 133mm, 20-spline output shaft

⚠ Please measure your original output shaft before purchasing.

There are many different output shaft designs used on QMB139 engines.

Differences may include:

• Overall Shaft Length
• Spline Count
• Wheel Size
• Bearing Journal Diameter
• Single vs. Dual Rear Shock Models
• Drum Brake vs. Disc Brake Applications
• Gear Ratios
• OEM Manufacturer Variations

Always compare:

• Overall Length (133mm)
• Spline Count (20 Splines on Both Ends)
• Bearing Diameters
• Thread Size
• Shaft Configuration

Failure to verify these dimensions may result in an incompatible part.

Replace your shaft if you notice:

• Worn Splines
• Bent Shaft
• Bearing Damage
• Gear Noise
• Excessive Play
• Transmission Failure
• Damaged Threads
• Rear Wheel Wobble
• Broken or Chipped Final Drive Components

• Professional installation is recommended.
• Inspect all transmission bearings before installation.
• Replace worn bearings and seals during rebuild.
• Inspect final drive gears for wear.
• Lubricate bearings and gears during assembly.
• Replace transmission oil after installation.
• Torque all fasteners to manufacturer specifications.

The output shaft is the final component that transfers engine power from the transmission to the rear wheel. A precision-machined replacement helps ensure:

• Smooth Power Delivery
• Proper Gear Alignment
• Reduced Transmission Wear
• Reliable Rear Wheel Drive
• Longer Gear and Bearing Life
• Improved Overall Drivetrain Reliability

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