Liquid threadlockers are anaerobic adhesives used on metal fasteners. The liquid cures to solid plastic in the absence of air. If you leave a puddle of threadlocker exposed to the air it will never harden. If you remove all the air, such as between two parts, the liquid will solidify. The presence of active metal such as copper or steel will speed the cure, while inactive metals such as stainless steel or cadmium plating cure slowly and may need to be primed. Loctite 7649 Primer N is a copper-filled spray that is applied to inactive surfaces to ensure cure, speed the cure, and cure to greater depths.
Threadlockers are formulated for different removal strengths: 222, or purple, is low strength designed for use on small fasteners that allow disassembly with a screwdriver; 242, 243, and 248 are blue, medium strength and can be removed with handtools; 262, 271, and 268 are red and considered permanent, designed to withstand tremendous removal forces; 220 low strength and 290 medium strength are wicking types designed for post-assembly application; and 272 is a high-temperature permanent version that withstands temperatures up to 450 degrees. By comparison, most other grades of threadlockers withstand temperatures of 300 degrees.
OEM's have used threadlockers for years. They are dependable, provide predictable removal, and are easy to use. Understanding the properties of your fastener is the first step in achieving maximum performance. Utilizing a liquid threadlocker takes it to the next level through maximum reliability. In most instances, these gas-, oil-, and chemical-resistant threadlockers are well worth the few cents it costs per application.
A used skidplate had to be sourced, as the original unit had been pretty well butchered because the new transmission mount sent two large bolts through a contoured section of the plate. The washers were angled on the contour, and holes had been cut with a torch for clearance. Modifications were made to the transmission/transfer-case mount positioning the bolts through a flat part of the replacement plate. Fastener length was critical for ground clearance and required sourcing both 2.5- and 2.75-inch bolt lengths. A removable threadlocker stick worked well and did not drip. | 
The transfer-case studs were slid into the adapter, and 243 liquid threadlocker was applied to each stud. Enough threadlocker was applied to fill the cleaned threads at the point where the nut will reside. The nuts were then torqued to the OEM specs listed for the stock NPG231 case and the excess liquid wiped away. |
The OEM skidplate bolts had begun to rust-seize. In the East, winter driving will cause severe corrosion, making fastener removal very difficult. Threadlocker will seal the mated threads and prevent rust seizing. | |