Metallics JG8HC262 Bolts 3/8-24 x 3-1/2 G8 HXBT St-zn (Jar 50)

It is fine thread: 3/8-24, with 24 threads per inch. It will not thread into a 3/8-16 coarse nut or a coarse-tapped hole. Fine thread is the common pitch on automotive and fleet work, so if the mating nut or tapped boss is 3/8-24 you are matched; if the existing hardware is 3/8-16, you need the coarse version instead.

Strength. The Grade 8 bolt is rated at 150,000 psi minimum tensile and 130,000 psi minimum yield, with a hardness of Rockwell C33-39, so it carries more load than a Grade 5 in the same diameter. That is why it gets specified on automotive and fleet work where a Grade 5 will not meet the required tensile strength. It is a medium carbon steel cap screw, heat treated.

Head width across flats measures 0.551 to 0.562 in., which is a 9/16 in. wrench or socket. The head is a standard hex.

Shank outside diameter runs 0.3690 to 0.3750 in., so it is a nominal 3/8 bolt and needs a hole drilled slightly oversize. A 3/8 in. (0.375) hole is a line-to-line fit at the top of the tolerance; drill 13/32 in. for a clean slip fit.

The bolt is steel with a zinc finish, which gives moderate corrosion protection for general indoor, enclosed, and sheltered use. It is not stainless, so in constant wet, coastal, or chemical exposure expect the plating to be sacrificial and plan on stainless or hot dip galvanized hardware instead. Note that galvanized and stainless are not available in Grade 8 strength, so if you need both the strength and heavy corrosion resistance, the joint design has to change.

Both the Buy American and ARRA compliance flags on the JG8HC262 bolt are marked compliant. Country of origin is listed as multiple, so if your specification requires a single named country of manufacture, confirm the origin on the lot you receive.

They ship in a jar of 50 pieces, and 50 each is the order minimum, so you buy by the full jar rather than loose counts. Jar weight is listed at 2427 g.

They are made to AISI 1021 to 1045 medium carbon steel and heat treated to the Grade 8 hardness range of Rockwell C33-39. That is the standard chemistry band for a Grade 8 cap screw, which is why the hardness and tensile numbers come out where they do rather than at Grade 5 levels.

The JG8HC262 is one size in the Metallics G8HC and JG8HC Grade 8 hex bolt series, and other sizes and pack quantities in the series are available by request. If you are standardizing a fleet or shop crib, specify the diameter, thread pitch, and length you need and it can be quoted from the same family.