HELICAL-COIL INSERT REPLACEMENT
THIS WORK PACKAGE COVERS:
Removal, Cleaning, and Installation
Expendable and Durable Items::
Extraction tool (see items 39-41 for size,
Lubricating oil (item 21, WP 0173)
Cleaning solvent (item 8, WP 0173)
General mechanic's tool kit (item 121, WP 0176)
Inserter tool (see items 66-70 for size, WP 0176)
Track Vehicle Repairer (1) 63H10
To permit higher stresses on studs and bolts that are set in aluminum castings, it is common
practice to install inserts of a stronger metal into which the studs or bolts are threaded. Helical-
coil and screw thread inserts are designated to perform this function. The AVDS-1790 family of
engines incorporates helical-coil inserts in many locations as original equipment. If the hole that
the original insert is installed in becomes oversize, a threaded insert may be used in its place to
allow the original size fastener to be used.
Helical-coil inserts are spiral steel coils having a right hand thread-shaped form on the inside and
on the outside diameter of the coils. A bar or tang at the bottom end of the coil, which is engaged
by an inserting tool, is used for threading the insert into the casting. Some inserts have a serrated
tooth section at the top end of the coil to stake them in place in the castings. Other inserts have
turns at the center of the coil in the form of a hexagon. This provides a locking effect when the
stud or bolt is threaded into the insert. Part or item numbers of tools, kits and inserts, in addition
to working dimensions are included in appropriate procedural work packages.
Do not damage threads of tapped
hole when using extraction tool.
Remove inserts from end of tapped
hole where the insert is closest.
Threads in tapped hole can be
1. Remove insert (1).
a. Place extraction tool (2) in insert (1).
Tap top of extraction tool (2) lightly
with hammer to "set" tool.
b. Maintaining a steady downward
pressure, turn tool (2) counter-
clockwise. Remove insert (1).
WP 0029 00-1