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Author Topic: Bolt head markings?  (Read 6364 times)

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Offline wohali

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Bolt head markings?
« on: December 09, 2010, 09:05:03 PM »
Hi there - enjoying a delicious egg nog and pondering what these Honda bolt head markings mean. I'm used to the current international markings - lines, or letters/numbers representing material and hardness. These look like a lowercase "b", or a pig snout (or is it two "D"s back to back?). I see a lot of the latter around the engine crank case.

Anyone know? I'm not planning to replace these, but what if I was?

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KingCustomCycles.com

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Re: Bolt head markings?
« Reply #1 on: December 10, 2010, 02:50:50 AM »
If I were to replace those, I would get a blown donor engine and use the bolts from it.  You are correct about bolt head markings having significance some of the time, stretch torque, close tolerance, alloy, etc.... and sometimes they are just manufacturer's marks meaning nothing. Since they are not standard, I would suspect they are just random manufacturer marks.
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Offline SohRon

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Re: Bolt head markings?
« Reply #2 on: December 10, 2010, 05:44:17 AM »
Those are 8's and 9's. They're standard Honda bolts correctly applied. Right that they represent hardness, etc. They can be had new from Honda or one of the vendors (BikebandiT, FI), or you can always get used bolts off ebay "box-o-bolts" auctions.
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Offline wohali

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Re: Bolt head markings?
« Reply #3 on: December 10, 2010, 04:12:56 PM »
Good to know that they're 8s and 9s, but obviously it's not the same as the current "grade 8".

Does anyone happen to have specs on these from Honda? This is all academic for me, my bolts are fine...I'm just curious if anyone know if there are modern equivalents that would fit the bill.
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Offline wildcatmahone

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Re: Bolt head markings?
« Reply #4 on: December 10, 2010, 04:43:05 PM »
Page 1-4 of the CB750 shop manual specifies that all threaded fasteners conform to ISO standards so yeh they're available, everywhere. Just watch out, grade 8 ISO bolts (used by the rest of the world) do not equal grade 8 SAE (Just the USA). The equivalent of a grade 8 SAE bolt is a grade 10.9 metric bolt.
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Offline wohali

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Re: Bolt head markings?
« Reply #5 on: December 10, 2010, 08:31:11 PM »
Do you have a table of conversions anywhere? I found this table but it's unclear to me. I see 8.8, 10.9, 12.9 and 14.9...
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