Free Metric Bolt Torque Chart - Grade 8.8
Download a print-ready metric torque specification chart for Grade 8.8 hardware. Covers M6 through M36 thread sizes with N•m and lb-ft values. Built for heavy-duty repair shops by ShopView.
Metric Torque Specs at Your Fingertips
Stop digging through service manuals for basic torque values. This chart covers the most common metric thread sizes (M6 through M36) for Grade 8.8 hardware, with both N•m and lb-ft values. Download the high-res version and print it, stick it on your toolbox, or hang it in the shop.
- Grade 8.8 metric hardware - M6 through M36
- Both N•m and lb-ft/lb-in values included
- Based on Caterpillar SENR3130 specifications
- Print-ready 300 DPI high-resolution PNG
- 4" x 7" magnet / sticker size
When to Use This Metric Torque Chart
Grade 8.8 is the most common metric bolt grade used in heavy-duty diesel applications. It has a tensile strength of 800 MPa and a proof load of 640 MPa — roughly equivalent to SAE Grade 5 in imperial sizing. If you're working on Caterpillar, Cummins, or Detroit Diesel engines, you'll encounter Grade 8.8 metric fasteners on engine mounts, turbo manifold studs, exhaust components, and accessory brackets.
Use this chart when the OEM service manual doesn't specify a torque value for a particular fastener, or when you need a quick reference for general-purpose Grade 8.8 metric hardware. These values apply to standard steel-into-steel applications with clean, dry threads. If the bolt threads into aluminum (like a cylinder head or intake manifold), use half the torque value shown.
Metric fasteners are identified by the "M" prefix followed by the nominal diameter in millimeters. The grade marking "8.8" is stamped on the bolt head. If you see a bolt marked "10.9" or "12.9," those are higher-strength grades and require different torque specifications — do not use this chart for those fasteners.
Metric Torque Quick Reference
Grade 8.8 hardware torque specifications with tolerances. Values are for clean, dry, steel-into-steel applications. Based on Caterpillar SENR3130. Always refer to the OEM service manual when available.
| Thread Size | Torque (N•m) | Torque (Imperial) |
|---|---|---|
| M6 | 12 ± 3 N•m | 105 ± 27 lb in |
| M8 | 28 ± 7 N•m | 250 ± 62 lb in |
| M10 | 55 ± 10 N•m | 41 ± 7 lb ft |
| M12 | 100 ± 20 N•m | 75 ± 15 lb ft |
| M14 | 160 ± 30 N•m | 120 ± 22 lb ft |
| M16 | 240 ± 40 N•m | 175 ± 30 lb ft |
| M20 | 460 ± 60 N•m | 340 ± 44 lb ft |
| M24 | 800 ± 100 N•m | 590 ± 75 lb ft |
| M30 | 1600 ± 200 N•m | 1180 ± 150 lb ft |
| M36 | 2800 ± 350 N•m | 2060 ± 260 lb ft |
For use on Grade 8.8 hardware. Specifications taken from Caterpillar SENR3130. Use only when service manual specifications are not available. If threads are into aluminum, use half torque.
Frequently Asked Questions
What is the torque spec for a Grade 8.8 M12 bolt?
A Grade 8.8 M12 bolt should be torqued to 100 ± 20 N•m (75 ± 15 lb-ft) when threading into steel with clean, dry threads. If the bolt threads into aluminum, use half torque: approximately 50 N•m (37 lb-ft).
What does Grade 8.8 mean for metric bolts?
The "8.8" marking indicates the bolt's strength class. The first number (8) means the bolt has a minimum tensile strength of 800 MPa. The second number (.8) means the yield strength is 80% of the tensile strength, or 640 MPa. Grade 8.8 is the standard strength class for most heavy-duty metric fastener applications.
Is Grade 8.8 the same as SAE Grade 8?
No. Despite the similar numbering, metric Grade 8.8 is roughly equivalent to SAE Grade 5, not Grade 8. SAE Grade 8 (150,000 PSI tensile strength) is closer to metric Grade 10.9 (1,040 MPa). This is a common source of confusion — always verify whether you're working with metric or imperial fasteners before selecting torque values.
Should I use N-m or lb-ft when torquing metric bolts?
Either unit works as long as your torque wrench is set correctly. N•m (Newton-meters) is the standard metric unit, while lb-ft (foot-pounds) is more common in North American shops. Most modern torque wrenches can switch between units. This chart provides both so you can use whichever your wrench displays.
What if the bolt threads into aluminum instead of steel?
When a bolt threads into aluminum (such as a cylinder head, intake manifold, or aluminum housing), use half of the torque value shown in the chart. Aluminum is softer than steel and the threads will strip at lower torque values. This half-torque rule is a widely accepted guideline from Caterpillar and other OEMs for general-purpose fasteners.
Can I use this chart for Caterpillar equipment?
Yes. The torque values in this chart are based on Caterpillar specification document SENR3130, which covers standard torque values for metric fasteners used across CAT equipment. These values apply as general guidelines when the specific service manual for your machine does not provide a torque specification for a particular fastener.
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