1/4-20 x 1in UNC Grade 8 Hex Cap Screw Yellow Zinc
A 1/4"-20 x 1" fully threaded Grade 8 hex head cap screw in yellow zinc. Heat-treated alloy steel meeting SAE J429 Grade 8 — 150,000 PSI minimum tensile strength. Sold in multiples of 25 pieces.
| Diameter | 1/4" (0.250") |
| Thread pitch | 20 TPI |
| Thread type | UNC — Unified National Coarse |
| Thread class | 2A |
| Length (under head) | 1" |
| Threading | Fully threaded |
| Head type | Hex head |
| Material | Medium carbon alloy steel, heat treated |
| Standard | SAE J429 Grade 8 |
| Proof load | 120,000 PSI |
| Min. yield strength | 130,000 PSI |
| Min. tensile strength | 150,000 PSI |
| Finish | Yellow zinc chromate |
| Head marking | 6 radial lines |
| SKU | HHCS141C8Y |
About Grade 8
Grade 8 is the highest-strength standard hex cap screw grade in the SAE J429 classification. At 150,000 PSI minimum tensile strength, it's substantially stronger than Grade 5 (120,000 PSI) and is the default spec for high-load, safety-critical, and high-vibration applications where a standard bolt isn't enough.
Grade 8 fasteners are produced from medium carbon alloy steel, heat treated, oil quenched, and tempered at a minimum of 800°F. This process gives them their strength — but also makes them more notch-sensitive than lower grades. Avoid using Grade 8 where significant bending, impact, or shock loading is expected; Grade 5 or a ductile alloy may be more appropriate in those cases. Always torque to the manufacturer's joint specification.
Identification: Grade 8 hex head cap screws have 6 radial lines on the bolt head. Grade 5 has 3 lines. Grade 2 has no markings. Check the head when verifying fastener grade during assembly or repair.
Need Grade 5 instead? See our Grade 5 UNC Hex Cap Screws. Need metric? See our Class 8.8 and 10.9 Metric Cap Screws.
Best For
- Automotive suspension and drivetrain — control arms, tie rods, differential mounts, and other high-load chassis connections
- Heavy equipment and agricultural machinery — anywhere a Grade 5 has been found to fatigue or loosen under load
- Structural and fabrication work — secondary structural steel connections, mounting plates, and frame assemblies
- High-vibration environments — engines, compressors, and industrial equipment where fastener loosening is a failure risk
- OEM replacement — matching the grade spec on assemblies originally built with SAE J429 Grade 8 fasteners
Shipping & Ordering
- Sold in multiples of 25 pieces
- Free shipping on orders $50 and over
- Ships within one business day from our warehouse
- Need a larger assortment? Our Grade 8 assortment kits cover 1/4" through 3/8", 1/2" or 3/4" diameters in a single organized bin or drawer — ideal for shops that need multiple sizes on hand
- B2B accounts: Fleet managers, facilities teams, and production shops can apply for a business account with better volume pricing and a dedicated rep — contact us to get started
Description
A 1/4"-20 x 1" fully threaded Grade 8 hex head cap screw in yellow zinc. Heat-treated alloy steel meeting SAE J429 Grade 8 — 150,000 PSI minimum tensile strength. Sold in multiples of 25 pieces.
| Diameter | 1/4" (0.250") |
| Thread pitch | 20 TPI |
| Thread type | UNC — Unified National Coarse |
| Thread class | 2A |
| Length (under head) | 1" |
| Threading | Fully threaded |
| Head type | Hex head |
| Material | Medium carbon alloy steel, heat treated |
| Standard | SAE J429 Grade 8 |
| Proof load | 120,000 PSI |
| Min. yield strength | 130,000 PSI |
| Min. tensile strength | 150,000 PSI |
| Finish | Yellow zinc chromate |
| Head marking | 6 radial lines |
| SKU | HHCS141C8Y |
About Grade 8
Grade 8 is the highest-strength standard hex cap screw grade in the SAE J429 classification. At 150,000 PSI minimum tensile strength, it's substantially stronger than Grade 5 (120,000 PSI) and is the default spec for high-load, safety-critical, and high-vibration applications where a standard bolt isn't enough.
Grade 8 fasteners are produced from medium carbon alloy steel, heat treated, oil quenched, and tempered at a minimum of 800°F. This process gives them their strength — but also makes them more notch-sensitive than lower grades. Avoid using Grade 8 where significant bending, impact, or shock loading is expected; Grade 5 or a ductile alloy may be more appropriate in those cases. Always torque to the manufacturer's joint specification.
Identification: Grade 8 hex head cap screws have 6 radial lines on the bolt head. Grade 5 has 3 lines. Grade 2 has no markings. Check the head when verifying fastener grade during assembly or repair.
Need Grade 5 instead? See our Grade 5 UNC Hex Cap Screws. Need metric? See our Class 8.8 and 10.9 Metric Cap Screws.
Best For
- Automotive suspension and drivetrain — control arms, tie rods, differential mounts, and other high-load chassis connections
- Heavy equipment and agricultural machinery — anywhere a Grade 5 has been found to fatigue or loosen under load
- Structural and fabrication work — secondary structural steel connections, mounting plates, and frame assemblies
- High-vibration environments — engines, compressors, and industrial equipment where fastener loosening is a failure risk
- OEM replacement — matching the grade spec on assemblies originally built with SAE J429 Grade 8 fasteners
Shipping & Ordering
- Sold in multiples of 25 pieces
- Free shipping on orders $50 and over
- Ships within one business day from our warehouse
- Need a larger assortment? Our Grade 8 assortment kits cover 1/4" through 3/8", 1/2" or 3/4" diameters in a single organized bin or drawer — ideal for shops that need multiple sizes on hand
- B2B accounts: Fleet managers, facilities teams, and production shops can apply for a business account with better volume pricing and a dedicated rep — contact us to get started
