Crankshaft balancer (harmonic damper) bolt
Torque-to-yield. This fastener is tightened past its elastic limit and permanently stretches. Always install a new one — a reused TTY bolt will not clamp to spec.
Tightening procedure
- Torque 111 lb-ft · 150 N·m
- Loosen Loosen 360°
- Torque 59 lb-ft · 80 N·m
- Angle 125°
Complete the passes in the order shown. Angle passes are turn-of-the-nut steps measured with an angle gauge after the preceding torque pass.
Variants
Some configurations of this fastener use a different procedure. Confirm which applies to your build before tightening.
With Z52 Dry Sump Option (final pass differs)
- Torque 111 lb-ft · 150 N·m
- Loosen Loosen 360°
- Torque 59 lb-ft · 80 N·m
- Angle 200°
Tools
- socket
- angle gauge
Notes
Use a new bolt (TTY). Multi-step: seat, fully loosen, then final torque plus angle. Z52 dry-sump uses 200 degrees on the final pass (variant). Catalog PN: GM 12557840 per figure 1Y00-083 callout 139 — "BOLT,CR/SHF BALR(M16X2.0X103) — Required: 01, Y 6.2W(LS3),6-SPD A/TRANS(MYC) (2010-2011) and Y 6.2W(LS3),6-SPD M/TRANS(MM6),(MZ6),(EXC DRY SUMP SYSTEM PKG(Z52) (2010-2011). M16x2.0 thread, 103mm long. Dry-sump (Z52) variant uses different bolt 11570163 (M16X2X125.75, 24mm socket, grade 10.9) — see variants in entry." Socket: 24mm across-flats (M16 thread, 24mm head) - confirmed by multiple LS builders on LS1Tech ("took it off with a 24mm socket").
Sources
- GM Fastener Tightening Specifications (6.2L LS3), Document ID 2296270
- 2011 Chevrolet Corvette Parts Catalog (GM Professional, Dec-11 supersedes May-11)
Values are cited as facts. We do not reproduce the manufacturer's prose, table layout, or diagrams.