National 3638 Manual Transmission Input Shaft Seal

Overview of National Manual Transmission Input Shaft Seal 3638

The National 3638 manual transmission input shaft seal is engineered to provide reliable sealing performance for a variety of vehicles including Buick, Chevrolet, Dodge, Ford, GMC, Jeep, Mercury, Oldsmobile, and Pontiac models. Designed with a polyacrylate material and a clockwise-spiral lip design, this oil seal helps maintain transmission integrity by preventing fluid leaks and contamination.

• Material: Durable polyacrylate for effective sealing
• Inside Diameter: 1.125 inches (28.580 mm)
• Outside Diameter: 1.628 inches (41.350 mm)
• Thickness: 0.190 inches (4.830 mm)
• Clockwise-spiral lip design for enhanced sealing
• Redicoat surface treatment for corrosion resistance
• Compatible with multiple makes and models including Ford Bronco, Chevrolet C10, Jeep Cherokee, and Pontiac Bonneville

Technical Details and Specifications

The National 3638 input shaft seal is part of the 3000 series and features a 48 type design optimized for manual transmissions. Its polyacrylate construction offers resistance to heat and wear, ensuring long service life. The seal’s inside diameter measures 1.125 inches (28.580 mm), fitting shafts of the same size, while the outside diameter is 1.628 inches (41.350 mm), matching housing bores of approximately 1.624 inches (41.250 mm). The thickness of 0.190 inches (4.830 mm) provides a secure fit without compromising flexibility. The clockwise-spiral lip design improves sealing efficiency by directing fluid back into the transmission, reducing leakage risks.

Compatible Vehicles and Applications

This manual transmission input shaft seal is compatible with a wide range of vehicles, including but not limited to:

• Buick LeMans, Skylark, and Riviera
• Chevrolet C10, C1500, and Suburban models
• Dodge Ramcharger and D-series trucks
• Ford Bronco, F-150, and Econoline vans
• GMC Sierra and Jimmy
• Jeep Cherokee, CJ5, and CJ7
• Mercury Cougar and Marauder
• Oldsmobile Delta 88 and Cutlass
• Pontiac Bonneville and Grand Prix

Common Issues Addressed by National 3638 Seal

• Prevents manual transmission fluid leaks around the input shaft
• Reduces contamination from dirt and debris entering the transmission
• Minimizes wear on transmission components by maintaining proper lubrication
• Helps avoid costly transmission repairs due to seal failure
• Maintains optimal transmission performance and longevity

Installation Notes and Tips

When installing the National 3638 input shaft seal, ensure the following for proper fitment and function:

• Clean the housing bore and shaft thoroughly before installation
• Inspect the shaft for wear or damage that could affect sealing
• Use appropriate tools to press the seal evenly into the housing bore without distortion
• Verify the seal’s lip orientation matches the clockwise-spiral design direction
• Apply a light coating of transmission fluid or compatible lubricant to the seal lip before installation

Quality Assurance and Warranty

National’s 3638 input shaft seal is manufactured to meet industry standards for durability and performance. The Redicoat treatment enhances corrosion resistance, extending the seal’s service life. While specific warranty terms may vary, National typically offers coverage against manufacturing defects to ensure customer confidence in the product’s reliability.