3/8"-20 BSF Grade R Zinc Hex Bolts With Shank

Product Description

3/8"-20 BSF Grade R zinc-plated steel hexagon-head bolts with a part-threaded plain shank, manufactured to the traditional BS 1083 British Standard Fine fastener pattern.

These high-tensile imperial bolts combine a conventional external hexagon head with an approximately 3/4" threaded section and a smooth unthreaded shank. They are suitable for classic vehicles, vintage motorcycles, agricultural machinery, heritage equipment and engineering assemblies that retain traditional British threads.

• Thread size: 3/8"-20 BSF
• Threads per inch: 20 TPI
• Thread series: BSF – British Standard Fine
• Thread form: 55-degree Whitworth form
• Construction: Part threaded with plain unthreaded shank
• Thread length: Approximately 3/4" / 19.05mm
• Available lengths: 1 1/4", 1 1/2", 1 3/4", 2", 2 1/4", 2 1/2", 2 3/4", 3", 3 1/2", 4", 4 1/2" and 5"
• Approximate metric lengths: 31.75mm, 38.1mm, 44.45mm, 50.8mm, 57.15mm, 63.5mm, 69.85mm, 76.2mm, 88.9mm, 101.6mm, 114.3mm and 127mm
• Head style: External hexagon head
• Width across flats: Approximately 9/16" / 14.29mm
• Head height: Approximately 1/4" / 6.35mm
• Material: High-tensile steel
• Strength grade: Grade R
• Approximate metric comparison: Property class 8.8
• Finish: Zinc plated
• Dimensional standard: BS 1083
• Thread standard: BS 84
• Pack sizes available: 1, 5, 10, 20, 50 and 100

These 3/8" BSF hexagon bolts are commonly used on classic British cars, vintage motorcycles, tractors, agricultural machinery, heritage equipment, restoration projects and older engineering assemblies.

The 20 TPI British Standard Fine thread uses the traditional 55-degree Whitworth thread form. The mating nut or tapped component must have the corresponding 3/8"-20 BSF thread. BSF, BSW, UNC, UNF and metric threads are not interchangeable.

The part-threaded construction provides a smooth, plain shank between the underside of the head and the threaded section. When the correct bolt length is selected, the supported components can bear against the solid shank rather than against the thread crests.

Each listed bolt has an approximately 3/4" threaded section. The remaining under-head length forms the plain shank, ranging from approximately 1/2" on the 1 1/4" bolt to 4 1/4" on the 5" bolt.

Grade R is a traditional British high-tensile fastener designation and is commonly regarded as broadly comparable to metric property class 8.8. This comparison is approximate and should not replace confirmation of the required mechanical specification for critical joints.

The zinc-plated finish provides a degree of corrosion resistance for general indoor use and sheltered outdoor applications. It is not normally recommended for prolonged exposure to marine, coastal or highly corrosive environments.

Hexagon bolt length is measured from directly beneath the head to the end of the bolt. The hexagon head is not included in the stated length.

Please note: BS 1083 is used as the dimensional reference for this traditional BSF hexagon-bolt pattern, while BS 84 defines the BSF thread series and 55-degree thread form. Dimensions and calculated shank lengths are intended as a guide and may vary within permitted manufacturing tolerances. Check the bolt where shank position, thread length, fit or mechanical performance is critical.

Please Note: Specifications given are intended as a guide only. If critical to your project please check with us first.