The Top Gear Oil Seal (Old Model) is a vital sealing component designed for the gearbox of vintage Royal Enfield motorcycles, specifically those with the 4-speed right-shift cast-iron engine. It is installed behind the top gear (sleeve gear) to prevent primary or gearbox oil from leaking into the final drive or onto the chain area.
Key Features
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Leak Prevention: Engineered to create a tight, high-pressure seal around the sleeve gear, ensuring oil stays within the gearbox housing.
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Heat & Friction Resistance: Made from high-quality nitrile rubber or specialized synthetic compounds that withstand constant rotational friction and high engine temperatures.
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Dual-Lip Design: Often features a dual-lip construction that keeps oil in while simultaneously preventing road dust and grime from entering the gearbox.
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Vintage Compatibility: Sized specifically for the output shafts of old-generation 350cc and 500cc Bullet and Standard models.
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Essential for Maintenance: Replacing this seal is a common part of gearbox overhauls to fix the “oil weep” typically found near the front sprocket area of older Enfields.
Technical Specifications
| Feature | Details |
| Compatibility | Bullet 350, Standard 350, Bullet 500 (Old 4-Speed Cast Iron Engines) |
| Material | Heavy-duty Nitrile Rubber with internal metal reinforcement |
| Placement | Gearbox Output / Sleeve Gear (Top Gear) |
| Function | Final Drive Oil Containment |









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