Place Bolts: Specifications & Dimensions

Place Bolts have a particular head shape that produces a “locking” motion between the bolt head and the material being clamped. The head flexes when it is tightened due to the combination of the recess under the head and the slots in the top of the head. This produces a spring action in the crown, allowing for extra elongation not possible with regular hex head cap screws. In high-vibration applications, this spring action provides improved resistance to loosening.

Place Bolts are produced to meet the dimensional specifications of the General Motors Type AA Hex Lock Bolts. Standard 5/8 and 3/4 Place Bolts are one wrench size smaller around the flat dimensions than regular hex head cap screws. For tight applications, the smaller head size may provide additional clearance. Place Bolts have a different resistance on the height of the heads than regular hex cap screws.

The Society of Automotive Engineers standard SAE J429 requires that place bolts be made of alloy steel and hardened to the Grade 8 strength mark.

Tensile Strength of 150,000 psi
Rockwell Hardness of Rc 33/39.

*The head measurements of "Place Bolt" and regular "Hex Head Cap Screws" are compared.