The Shacman X5000 Plain Washer, Small Series with OEM number 90003930251 is a precision-engineered flat washer designed for critical bolted joints in heavy-duty trucks. This genuine component provides load distribution, prevents surface damage, and maintains clamp force under vibration. The 90003930251 plain washer is manufactured from high-carbon spring steel, heat-treated to achieve optimal hardness and elasticity.
In Shacman X5000 applications, this small-series plain washer is used extensively on engine brackets, transmission mounts, chassis components, and cab fasteners. OEM 90003930251 ensures consistent thickness, parallel faces, and a burr-free surface that prevents stress risers. Unlike commercial-grade washers, the genuine part features a zinc-plated finish that resists corrosion for over 1,000 hours in salt spray tests.
A missing or undersized washer can lead to bolt loosening, embedment into soft aluminum components, and eventual joint failure. The 90003930251 plain washer solves this with a carefully controlled hardness range of 42–50 HRC, ensuring it compresses slightly under load without cracking. Its small series designation refers to the compact outer diameter suitable for confined spaces around engine blocks and transmission housings.
Choosing genuine OEM 90003930251 guarantees dimensional accuracy to ISO 7089 standards, with an inner diameter tolerance of H13 and outer diameter tolerance of h14. Each batch is 100% inspected for surface defects, hardness, and plating adhesion. Upgrade your Shacman X5000 fastening reliability with this critical yet often overlooked component.
In heavy-duty truck assemblies, a plain washer is not just a spacer. The 90003930251 distributes bolt preload evenly across the clamped material, preventing embedding into softer surfaces like aluminum cylinder heads or plastic composite brackets. Genuine Shacman washers maintain flatness under high clamp loads, reducing the risk of loosening due to embedment relaxation.
Aftermarket washers often use low-carbon steel with insufficient hardness, leading to deformation, burrs, or cracking. OEM 90003930251 is made from spring steel that retains elastic recovery, ensuring the washer does not become a “loose ring” after torque cycling. This directly improves joint reliability and prevents fastener fatigue.
When assembling Shacman X5000 components, always place the plain washer directly under the bolt head or nut, not between stacked washers. Ensure the chamfered side of the bolt head contacts the washer face. For high-vibration areas (e.g., engine mounts), use a combined assembly of plain washer + lock washer, with the plain washer contacting the part surface.
Tighten to the torque specified in Shacman workshop manuals. Over-torquing can embed the washer edge into the part, while under-torquing leaves the washer loose. Replace any washer that shows signs of cracking, bending, or corrosion. For critical joints, use new OEM 90003930251 washers each time the fastener is removed.
Each 90003930251 washer starts as a precision-blanked strip from annealed C67S steel. After blanking, components undergo austenitizing, oil quenching, and tempering to achieve a uniform martensitic structure. Hardness is verified by Rockwell testing on every batch, with a target of 46 HRC average for optimum toughness.
The zinc plating process includes alkaline non-cyanide zinc, followed by yellow or trivalent clear passivation. A sealant topcoat adds additional corrosion protection. Shacman requires a cross-cut adhesion test per ISO 2409 and a copper-accelerated salt spray test to ensure the coating survives 720 hours without white rust.
OEM 90003930251 replaces Shacman part numbers 90003930250, 612600010143, and DZ13241805017. It is fully compatible with Shacman X5000 trucks across all production years (2015–present), including WP12, WP13, and ISM engine variants. The small series profile is also suitable for X3000 and X6000 chassis fastening points where space is limited.
This washer is designed to work with property class 8.8 and 10.9 bolts. For class 12.9 bolts, Shacman recommends using hardened washers; the 90003930251 meets that requirement with its 46 HRC typical hardness. When replacing fasteners in safety-critical areas (steering, brakes), always use genuine washers to maintain homologation.
For fleet maintenance, keeping an assortment of 90003930251 washers in sizes M6, M8, M10, and M12 ensures rapid repair of loose engine brackets, transmission mounts, and cab isolators. Invest in genuine Shacman plain washers for long-term joint reliability and reduced rework.
Shacman’s quality system tests each production lot of 90003930251 for: flatness deviation (<0.1 mm per 25 mm diameter), Rockwell hardness (HRC scale), coating thickness (X-ray fluorescence), and salt spray resistance (ASTM B117). Additionally, random samples are subjected to a hydrogen embrittlement test per ASTM F519 to guarantee no delayed cracking.
The washers are also torque-tested in an assembled joint to verify that the washer does not deform or cause a drop in clamp load after 1,000 vibration cycles (SAE J1455). Only after passing all criteria are the washers packaged for OEM and aftermarket distribution. This rigorous process ensures the 90003930251 delivers the same quality as the washers originally installed on your Shacman X5000 assembly line.
