Overview
ISO 9704:1990 specifies the main dimensions and general requirements for wiper arm to shaft end connections used on passenger cars. The standard defines preferred and non-preferred connector types, dimensional drawings and tables, material and hardness limits, and fastening requirements to ensure reliable mechanical engagement between wiper arms and shaft ends. Although written for passenger cars, ISO 9704 can be applied to other vehicle classes where no specific international standard exists.
Key topics and technical requirements
- Connector types
- Type 1 (preferred): Conical, knurled shaft ends (normative in the main text).
- Type 2 (non-preferred, Annex A): Knurled-drive (entraîneur) shaft ends with a locking system - provided as a normative annex for markets where this form remains common.
- Dimensions and profiles
- Principal dimensions for shaft ends and arm-holes are given in figures and tables in the standard; tooth/profile geometry requirements (e.g., tooling tooth apex angle) are specified for repeatable manufacturing.
- Materials and hardness
- Shaft-end material: Steel with a specified minimum superficial hardness (document gives minimum 135 HB).
- Wiper arm/arm-hole material: Maximum superficial hardness specified (document gives maximum 110 HB).
- Type 2 materials: Knurled driver made from zinc alloy or sintered iron; arm end may be zinc or aluminium alloy (Annex A).
- Fastening and torque
- Recommended tightening torques are specified by nominal thread size and apply to assemblies with washers and galvanized nuts (torque values are provided in the standard tables).
- Coatings and tolerances
- Dimensional allowances for painted or coated fittings are addressed (Annex A guidance on increasing hole dimensions when coatings are applied).
Applications and who uses this standard
- Automotive OEM design and engineering teams specifying wiper system interfaces
- Component suppliers (wiper arms, motor shafts, repair parts) ensuring interchangeability
- Aftermarket manufacturers and fitment engineers matching replacement parts
- Quality, test and regulatory laboratories validating mechanical fit, hardness, and torque
- Vehicle homologation and procurement teams seeking standardized wiper interface specifications
Related standards
- ISO 9704 was developed by ISO/TC 22 (Road vehicles). It complements other vehicle component and safety standards covering wipers and windshield systems; users should consult relevant ISO/TC 22 standards for broader wiper-system requirements.
Keywords: ISO 9704, wiper systems, shaft ends, arm-holes, passenger cars, wiper arm connection, knurled shaft, conical shaft, material hardness, tightening torque.