The lines on the head of a bolt indicate its grade. SAE J429 (Society of Automotive Engineers) bolts have radial lines, whereas ASTM (American Society for Testing and Materials) uses a combination of letters and numbers to indicate the grade. Three radial lines will indicate an SAE grade 5 fastener, while six radial lines will indicate an SAE grade 8 fastener. These are the most common grades, but there are others. Our Fastener Identification Markings Chart has a complete list of bolt grades with accompanying head markings.
I have a bolt, don’t know who makes them its a torx plus with a anchor stamped on the face
@John- I am sorry, but that does not immediately ring a bell. If you’d like to send in a photo, perhaps we can decode it for you.
I have a bolt top of head says -FNL
Center of head Has 9 dashes in the center
Bottom of the Bolt says G9
Wondering about the grade of this bolt
@Jason- FNL is likely the bolt manufacturer, Fastenal. The G9 and nine dashes signify grade 9, which is a high strength grade slightly stronger than SAE grade 8. Grade 9 is a grade that was created to be a high strength alternative to SAE grade 8, but is not covered specifically by SAE J429 nor any other standards organization.
I have a very old A286 fastener spec that refers to marking codes such as H19 and H28 on the head. We don’t know what that means. Anybody?
@Tim – Apologies, but we are not familiar with those headmarkings.
have 1969 vet bolts holding rear spring have a w8 or wb on head corvette supplier sells grade 5 bolt as replacement are these strong enough
@Paul – I am not familiar with a ‘W8’ or ‘WB’ marking on the head of a bolt, so I am not certain what grade they might be. Sorry we cannot help.
Am looking for a cheesehead bolt 3/8-16 1 1/4 can any help
@Peter – I am sorry, but that is not a fastener we can supply. Apologies.