Dust Seal 20x32x5

This aftermarket dust seal is engineered for the SYM Jet X 125I 125cc scooter, compatible with 2021-2022 model years and cross-referenced to OEM number 90754-M9Q-000. The 20x32x5mm seal provides critical protection for rotating shaft applications, excluding dust, water, and road debris while retaining lubricant within the bearing or gearbox assembly.

The seal features a dual-lip design that provides redundant sealing capability. The primary lip, angled at 25° relative to the shaft axis, maintains continuous contact pressure through a garter spring that applies uniform radial load around the entire circumference. This primary lip excludes external contaminants and retains internal lubricant under dynamic conditions. The secondary lip, positioned axially behind the primary, provides a second barrier that traps any particles that penetrate the primary seal, while also retaining a thin film of lubricant that reduces friction and wear on the primary lip. Between the two lips, a dust groove collects trapped particles, preventing them from reaching the bearing or gearbox internals.

The seal body is molded from nitrile butadiene rubber (NBR), selected for its excellent resistance to petroleum-based lubricants, good abrasion resistance, and wide operating temperature range. The NBR compound is formulated with a Shore A hardness of 70±5, providing sufficient stiffness for structural integrity while maintaining the elasticity necessary for lip conformity to the shaft surface. The metal case is manufactured from cold-rolled steel with a zinc phosphate coating that prevents corrosion and provides adhesion for the rubber molding process. The garter spring is 304 stainless steel wire, resistant to the hot oil environment and thermal cycling.

Technical specifications: dimensions 20x32x5mm (shaft x bore x width); material NBR 70 Shore A; spring: 304 stainless steel; temperature range -30°C to 120°C continuous, 150°C intermittent; maximum shaft speed 3,000 RPM; pressure rating 0.5 bar differential; lip angle 25° primary, 15° secondary.

The seal is designed for press-fit installation into a housing bore machined to H7 tolerance, with the seal outer diameter at s7 interference fit ensuring retention without adhesive. The shaft surface finish should be 0.4-0.8μm Ra for optimal lip wear characteristics—rougher surfaces accelerate lip wear, while excessively smooth surfaces may not retain adequate lubrication film. During installation, apply a thin film of compatible grease to the seal lip to prevent dry-running damage during initial startup.

Replace this seal when: oil seepage is visible at the seal lip, the shaft shows scoring or rust under the seal contact zone, the seal lip is hardened or cracked from thermal aging, or during any disassembly of the protected component. In dusty or wet riding conditions, inspect the seal annually for damage and replace proactively to prevent contamination of wheel bearings or speedometer drive gears.