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Why the LS-8704 Steel Thread Insert is Vital for Cat 3406 Head Bolt Restoration
Eliminate pulled head bolt threads and restore factory clamping strength with 3-1/4" heavy-wall alloy inserts.
Facing a stripped, pulled, or galled cylinder head bolt thread on a Caterpillar 3406, 3406B, 3406C, or 3406E engine block? Don't sentence an expensive cast-iron block to the scrap yard. The LS-8704 Solid Steel Deck Thread Insert restores full factory head bolt clamping force and structural deck integrity right in-frame.
The Critical Engineering of Large-Bore Block Deck Clamping
On heavy-duty Caterpillar 3406 series engines, the cylinder head bolts must withstand intense multi-stage torque values followed by severe angular turn specifications. This massive clamping load is necessary to compress the head gasket fire-rings and contain peak combustion pressures. Over hundreds of thousands of miles, thermal stress, repeated head gasket overhauls, coolant weeping, or over-torquing can cause the original cast-iron threads inside the block deck to fatigue, gall, or strip out completely. Attempting to repair these high-load threads using wire-wound helical coils or light-duty thin-wall sleeves is an absolute recipe for failure. Helical inserts lack the wall thickness and engagement area needed to handle high-tensile head bolt stretch, causing the repair to pull straight out of the deck during torque passes. The LS-8704 solid steel thread insert completely solves this structural vulnerability. Featuring a heavy-wall 3-1/4" overall length with 7/8" x 16 TPI external threads and 3/4" x 16 TPI internal threads, it distributes head bolt tension deep into fresh, solid block metal for permanent, leak-free deck clamping.
- Precision Engine-Specific Thread Dimensions – Engineered with exact 3/4" x 16 TPI internal threads and 7/8" x 16 TPI external threads for Cat 3406 deck repairs.
- Full-Length 3-1/4" Engagement Depth – Provides maximum thread engagement down the block deck well, matching factory head bolt engagement depth parameters.
- Heavy-Wall Solid Steel Construction – High-tensile alloy steel body resists thread deformation, wall collapse, and pulling under extreme head bolt torque-angle loads.
- In-Frame Block Repair Solution – Reams and taps into damaged block deck holes (ideally paired with the M20111-B repair fixture) to save high-value engine blocks without removal.
- Tiered Volume Pricing Available – Cost-effective single replacement ($56.00) with volume tier discounts down to $32.48 for high-volume engine rebuilders and fleet shops.
Stop Scrapping Damaged Caterpillar Blocks. Lock In Permanent Deck Thread Strength.
The LS-8704 Caterpillar 3406 Bolt Hole Thread Insert is an indispensable component for heavy equipment machine shops, commercial truck service bays, diesel engine rebuilders, and fleet repair facilities. Restore factory torque capacity, eliminate head gasket blowouts, and rebuild with total confidence using Apex.
3-1/4″ Solid Steel Thread Insert. Restore Cat 3406 Clamping Force.
Order LS-8704 Thread Inserts – From $32.48Technical Specifications
| Technical Metric | Value / Specification Guidelines |
|---|---|
| Target Engine Compatibility | Caterpillar 3406, 3406B, 3406C, and 3406E Heavy-Duty Engines |
| Internal Thread Dimensions | 3/4" X 16 TPI (Threads Per Inch) - Fits OEM Head Bolts |
| External Thread Dimensions | 7/8" X 16 TPI (Threads Per Inch) - Oversized Block Tapping |
| Overall Length | 3-1/4 Inches (3.25") Full-Depth Engagement |
| Material Metallurgy | High-Tensile Solid Alloy Steel with Protective Surface Coating |
| Recommended Fixture Tooling | M20111-B Headbolt Hole Repair Alignment Fixture |
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