SAE J429 Grade 8 Bolts
Grade 8 is medium-carbon alloy steel, quenched and tempered. It is used where a joint needs high clamp load: heavy equipment, trailers, suspension and similar service where specified.
| Marking | 6 radial lines, 60 degrees apart, plus manufacturer ID |
|---|---|
| Matching nut | SAE J995 Grade 8 |
| Washer | Hardened washer recommended |
Mechanical properties (SAE J429)
| Size | Proof | Yield (min) | Tensile (min) | Hardness |
|---|---|---|---|---|
| 1/4 to 1-1/2 in | 120 ksi | 130 ksi | 150 ksi | C33 - C39 |
These tables carry the same figures as the printed sheet below.
The printed sheet
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Text version of this sheet
SAE J429 · inch steel bolts and screws · high strength
What it is
FIELD IDENTIFICATION
Grade 8 is medium-carbon alloy steel, quenched and tempered. It is used where a joint needs high
clamp load: heavy equipment, trailers, suspension and similar service where specified.
MFG
Marking
6 radial lines, 60 degrees apart, plus manufacturer ID
Matching nut
SAE J995 Grade 8
Washer
Hardened washer recommended
Grade 8: 6 radial lines, 60 degrees apart
Mechanical properties (SAE J429)
Size
1/4 to 1-1/2 in
Proof
Yield (min)
120 ksi
Tensile (min)
130 ksi
Hardness
150 ksi
C33 - C39
Key points
Hardness is high enough that electroplated finishes carry hydrogen-embrittlement risk. Plated Grade 8 must be baked promptly after plating, or use a nonelectrolytic coating.
Upgrading Grade 5 to Grade 8 is only safe if the nut, washer, tapped hole and joint can take the extra load.
SAE J429 covers inch bolts and screws up to 1-1/2 in only. It is not a structural (F3125) or pressure/temperature (A193) specification.
Grade 8 is not A325 or A490: structural bolts are a system with their own head, thread length, nut, washer and installation rules.
What it is not
Not an A490 substitute. A490 is a structural system with its own rules.
Not interchangeable with class 10.9 metric despite similar strength.
Governing standards: SAE J429 (2014); SAE J995 (2017) (nuts). Editions shown are the latest confirmed as of September 2026. The drawing and the governing standard always
take precedence over this sheet.
torquing any fastener. Verify the current governing standard, project documents, OEM requirements, size, thread, coating and lot certification. To the fullest extent permitted by law, The Fastener App disclaims liability
arising from reliance on this reference.
Fastener Guide reference FG-DD4C6E · thefastenerapp.com/fastener-guide/technical-reference/sae-j429-grade-8-bolts · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
