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T.8.2 Critical Fastener Requirements
T.8.2.1 Any Critical Fastener must meet, at minimum, one of the following:
SAE Grade 5 -
Metric Grade 8.8 -
AN/MS Specifications
Equivalent to or better than above, as approved by a Rules Question or at Technical Inspection
T.8.2.2 All threaded Critical Fasteners must be one of the following:
Hex head
Hexagonal recessed drive (Socket Head Cap Screws or Allen screws/bolts)
T.8.2.3 All Critical Fasteners must be secured from unintentional loosening with Positive Locking Mechanisms see T.8.3
T.8.2.4 A minimum of two full threads must project from any lock nut.
T.8.2.5 Some Critical Fastener applications have additional requirements that are provided in the applicable section.
Explanation
T.8.2.1 Any Critical Fastener must meet, at minimum, one of the following:
SAE Grade 5 -
Metric Grade 8.8 -
AN/MS Specifications
Equivalent to or better than above, as approved by a Rules Question or at Technical Inspection
Critical Fasteners have to meet a minimum quality requirement. Quality is affected by material type, tensile strength, etc.
SAE Grade 5
SAE Grade is a US standard grading system developed by the Society of Automotive engineers. They use a system where there is a different number of raised dashes on each bolt to indicate the grade and strength of the bolt. We are required to use at least Grade 5 which will have 3 raised dashes (higher grades are stronger)
SAE Grade 5 Specs: (Source: Home Depot Website (embedded above))
Head Marking: Three radial lines
Material: Medium carbon steel, quenched and tempered
Size Range: 1/4-inch to 1-inch
Proof Load (psi): 85,000
Min. Yield Strength (psi): 92,000
Min. Tensile Strength (psi): 120,000
Size Range: Over 1-inch to 1 1/2-inch
Proof Load (psi): 74,000
Min. Yield Strength (psi): 81,000
Min. Tensile Strength (psi): 105,000
Metric Grade 8.8
Similarly to SAE grades, there are also metric grades. These grades are established by the ISO (International Standards Organization). The grade of the bolt is indicated by the actual number being stamped into the bolt (e.g. Grade 8.8 would have an "8.8" written on the bolt head)
Metric Grade 8.8 Specs: (Source: Home Depot Website (embedded above))
Head Marking: 8.8
Material: Medium carbon steel, quenched and tempered
Size Range: All sizes below 16-mm
Proof Load (MPa): 580
Min. Yield Strength (MPa): 640
Min. Tensile Strength (MPa): 800
Size Range: 16-mm to 72-mm
Proof Load (MPa): 600
Min. Yield Strength (MPa): 660
Min. Tensile Strength (MPa): 830
AN/MS Specifications
AN stands for Army-Navy aircraft applications, and MS stands for Military Standard.
These fasteners are intended for high performance military/ aircraft applications, which is why they are acceptable (potentially overkill) for FSAE.
Equivalent to or better than above, as approved by a Rules Question or at Technical Inspection
If you can prove that your fastener is better than the provided options (not sure why you would need to) then you can use it. This has to be validated by SAE judges through a rules question response or at technical inspection.
T.8.2.2 All threaded Critical Fasteners must be one of the following:
Hex head
Hexagonal recessed drive (Socket Head Cap Screws or Allen screws/bolts)
All threaded Critical Fasteners must either have a hex head, or a recessed hex drive. This means you need the hex shape (no phillips head bolts) but you getr to choose if that is the external hex shape, or recessed hex shape.
This is what a hex head looks like. You can use wrenches and socket wrenches to fasten this.
This is what a socket head cap screw / allen screw/ bolt looks like. You can use allen keys to fasten this.
T.8.2.3 All Critical Fasteners must be secured from unintentional loosening with Positive Locking Mechanisms see T.8.3
Positive locking mechanisms are mechanisms that prevent fasteners from becoming loose by accident (this happens a lot due to vibrations, lots of things including the FSAE car vibrate enough to loosen bolts if there is not something to dampen this vibration). More information about Positive Locking Mechanisms can be found on the next page.
T.8.2.4 A minimum of two full threads must project from any lock nut.
There has to be at least two threads projecting from nuts used to fasten parts to the car.
At least 2 threads project from the nut
Less than 2 threads project from the nut. This is not rules compliant.
T.8.2.5 Some Critical Fastener applications have additional requirements that are provided in the applicable section.
Keep an eye out for additional Critical Fastener requirements based on specific applications
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