1/4"-26 BSF Grade R Zinc Hex Bolts With Shank

Product Description

1/4"-26 BSF Grade R zinc-plated steel hexagon-head bolts with a part-threaded shank, manufactured to the traditional BS 1083 British Standard Fine fastener pattern.

These high-tensile imperial bolts combine a conventional external hexagon head with a 1/2" threaded section and a plain unthreaded shank. They are suitable for classic vehicles, vintage motorcycles, agricultural machinery, heritage equipment and engineering assemblies that retain traditional British threads.

• Thread size: 1/4" BSF
• Threads per inch: 26 TPI
• Thread series: BSF – British Standard Fine
• Thread form: 55-degree Whitworth form
• Construction: Part threaded with an unthreaded shank
• Thread length: Approximately 1/2" / 12.7mm
• Available lengths: 1", 1 1/4", 1 1/2", 1 3/4", 2", 2 1/2", 3" and 3 1/2"
• Approximate metric lengths: 25.4mm, 31.75mm, 38.1mm, 44.45mm, 50.8mm, 63.5mm, 76.2mm and 88.9mm
• Head style: External hexagon head
• Width across flats: Approximately 7/16" / 11.11mm
• Head height: Approximately 3/16" / 4.76mm
• 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 1/4" BSF hexagon bolts are commonly used on classic British cars, vintage motorcycles, tractors, agricultural machinery, heritage equipment, restoration projects and older engineering assemblies.

The 26 TPI British Standard Fine thread uses the traditional 55-degree Whitworth thread form. The mating nut or tapped component must have the corresponding 1/4"-26 BSF thread. BSF, BSW, UNC, UNF and metric threads are not interchangeable.

The part-threaded construction provides a smooth, plain shank between the head and threaded section. Where correctly sized for the joint, the unthreaded shank can pass through the supported components so that shear loads act on the solid shank rather than across the threads.

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

Grade R is a traditional British high-tensile fastener designation and is commonly regarded as broadly comparable to metric property class 8.8. It should not be confused with stainless-steel grades, SAE grades or metric property-class markings.

The 7/16" width across flats is the actual hexagon measurement. Traditional Whitworth and BSF spanners may be marked according to the nominal thread size rather than the measured jaw opening, so confirm correct tool fit before applying torque.

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 are intended as a guide and may vary within permitted manufacturing tolerances. Check the bolt where shank length, 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.