Grade 5 vs Grade 8 Bolts: Complete Comparison
⚡ Quick Answer
Use Grade 5 for:
- General automotive and machinery
- Non-critical structural connections
- Cost-sensitive applications
- Most everyday applications
Use Grade 8 for:
- High-stress critical applications
- Suspension and steering components
- Heavy equipment
- Towing and hitches
Specification Comparison
| Property | Grade 5 | Grade 8 | Difference |
|---|---|---|---|
| Tensile Strength | 120,000 psi | 150,000 psi | Grade 8 is 25% stronger |
| Yield Strength | 92,000 psi | 130,000 psi | Grade 8 is 41% higher |
| Proof Load | 85,000 psi | 120,000 psi | Grade 8 is 41% higher |
💡 Quick Tip
Remember: More lines = More strength. Grade 5 has 3 lines, Grade 8 has 6 lines.
Load Capacity by Size
| Bolt Size | Grade 5 | Grade 8 |
|---|---|---|
| 1/4"-20 | 3,800 lb | 4,750 lb |
| 3/8"-16 | 9,200 lb | 11,500 lb |
| 1/2"-13 | 17,000 lb | 21,250 lb |
| 3/4"-10 | 40,100 lb | 50,100 lb |
⚠️ Important
Values are for dry threads. Lubricated threads require 20-30% less torque.