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Old 01-27-2020, 05:09 AM
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Default Grade 8 bolts necessary?

Hello I was just wondering if grade 8 bolts are necessary in go karts. I want to bolt pillow block bearings onto a frame and only have regular bolts on hand. I would need (4) 1/2 diameter bolts.
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Old 01-27-2020, 06:08 AM
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Not really but they are much nicer than plain ones considering ive snapped cheap ones with a walmart rachet never broke a grade 8
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Old 01-27-2020, 07:25 AM
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I ALWAYS get Grade 8 bolts when I can. They are simply far superior to cheap hardware.
As pillow blocks are rather crucial, get the absolute best hardware you can! It will be safer, more reliable, and save you headaches later if you ever try to take it apart.
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Old 01-27-2020, 07:32 AM
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Even 307a, butter bolt 1/2-13 provide 3831 lbs of clamp load, across 4 bolts 15,324 lbs of clamp load even with the weakest bolts, that axle is not going anywhere.

Grade 2, 5 or 8 are stronger and perfectly fine, just dont overtorque things.

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Last edited by karl; 01-27-2020 at 08:48 AM. Reason: lol
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Old 01-27-2020, 08:26 AM
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If the fastener is stronger than what you're fastening, it's kind of a waste of money. And there are some times where it's better for the bolt to yield a little instead of snap. It's all a rather complex engineering process to determine fastener strength. Use of too high a tensile strength fastener can be detrimental do a design as well.

Typical high strength structural bolts are A325, which is the same alloy as grade 5. Use of a grade 8 hardware, while it might seem "better" would be an automatic fail on inspection in many applications.
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Old 01-27-2020, 10:06 AM
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Use the best quality you can afford.. If anything get the better ones later, when you can afford them......
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Old 01-27-2020, 10:25 AM
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Pillow block bearings will only need grade 5. Suspension parts, it's a toss up. It's sometimes better for a bolt to bend, than snap, especially with critical parts.
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Old 01-27-2020, 11:16 AM
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Quote:
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Remember kids, The best way to get the right answer on the Internet is not to ask a question, it's to post the wrong answer
Works a treat
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Old 01-27-2020, 05:44 PM
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Like the youtube guy making front spindles, he was adamant about using grade 8, 3/4 dia bolts....then, yup you guessed it! Proceeded to weld them on will so much heat...the hazing covered most of the unthreaded part of the bolt. Grade 5 is perfect for carts
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Old 01-27-2020, 10:33 PM
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Thanks for the replies guys I was really appreciate the help.
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