Chevy LS1 Flywheel Torque Sequence Diagram
LS1 six-bolt flywheel/flexplate sequence with GM's 20, 50 and 100 N-m passes, threadlocker and orientation guidance.
GM's cited LS1 procedure uses three passes in sequence for either the manual flywheel or automatic drive plate: 20 N-m (15 lb-ft), 50 N-m (37 lb-ft), then 100 N-m (74 lb-ft). Apply the specified threadlocker and use the six-bolt opposite-side order. Preserve orientation because GM notes that the flywheel has no locating pin and is drawn onto the crankshaft by the bolts.
The flywheel or flexplate is both a rotating engine component and the connection to the clutch or torque converter. Uneven seating at the crank flange can create runout, starter-ring-gear problems, vibration or bolt fatigue. For the Chevy LS1 5.7L, the correct value is inseparable from crank flange, fastener, thread treatment and installed transmission hardware.
GM uses the same three stages for the cited manual and automatic engine flywheel assemblies, but converter and clutch-cover bolts remain separate joints.
The interactive pattern alternates across the bolt circle to draw the part onto the crank flange evenly. It is a tightening controller, not a claim that every engine carrying the same family name has the same bolt count. Compare the actual flange, service illustration and replacement-part instructions before applying torque.
Interactive Chevy LS1 5.7L crank-flange sequence
STAR PATTERN
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A 6-fastener opposite-side controller. Select 1 through 6; the physical labels around the circle are 1-4-2-5-3-6. Confirm that the installed flange matches.
Chevy Ls1 Flywheel Torque Sequence Diagram
| APPLICATION / ITEM | SPECIFICATION | NOTES |
|---|---|---|
| Pass 1 | 20 N-m / 15 lb-ft | In sequence |
| Pass 2 | 50 N-m / 37 lb-ft | Repeat sequence |
| Final pass | 100 N-m / 74 lb-ft | Repeat sequence |
| Threads | Specified threadlocker | GM 12345382 or equivalent |
The LS1 production procedure is a three-stage clamping process. It does not cover later eight- or nine-bolt LS/LT crank flanges or aftermarket fasteners.
How to use this specification correctly
- 01
Confirm the engine code, crankshaft/rear-seal generation, transmission type, flywheel or flexplate part number, balance specification and fastener part number. Photograph orientation marks before removal.
- 02
Disconnect the battery and support the engine and transmission with rated equipment. A flywheel is heavy and a thin flexplate has sharp edges; use eye protection and a flywheel holding tool rather than hands or a screwdriver jammed into the ring gear.
- 03
Remove the clutch/torque-converter fasteners and transmission according to the vehicle manual. Mark converter depth before separation and keep the converter fully seated in the transmission pump.
- 04
Inspect the crank flange, register, bolt holes, rear seal, pilot bearing, ring gear and both faces of the flywheel/flexplate. Reject cracks, heat checking beyond limits, elongated holes, damaged teeth or an unapproved resurfaced thickness.
- 05
Clean mating faces so the part seats metal-to-metal. Keep oil, grease and threadlocker off friction surfaces. Chase threads only if the service procedure permits it and blow blind holes clear without spraying solvent into the engine.
- 06
Apply the specified threadlocker, position the documented face toward the transmission and hand-start all six bolts without using them to overcome a misaligned register.
- 07
Tighten 1-4-2-5-3-6 at 20 N-m, repeat at 50 N-m, then repeat at 100 N-m. Inspect seating after every pass.
- 08
Install clutch, pressure plate or converter hardware only after the crank-flange joint is complete. Use alignment dowels and the separate pressure-plate/converter torque specification.
- 09
Measure flywheel/flexplate runout where the manual requires it and rotate the crankshaft by hand. Verify starter engagement, converter freedom/endplay and bellhousing alignment before final installation.
- 10
After startup, stop for scraping, cyclic knock or abnormal vibration. Recheck accessible converter/inspection-cover work only by the application procedure; do not casually retorque sealed crank bolts after operation.
Selecting the correct application branch
GM uses the same three stages for the cited manual and automatic engine flywheel assemblies, but converter and clutch-cover bolts remain separate joints.
The flywheel is not located by a dowel in this procedure. Mark direction before removal and align the bolt pattern without forcing a bolt into an offset hole.
How the opposite-side sequence works
With 6 matching fasteners, the controller's physical labels are 1-4-2-5-3-6 around the circle. Tighten numerically so each step crosses or moves far from the previous position. Start every bolt by hand before the first staged pass.
Use several even preliminary passes when the source gives only a final torque, unless its instructions say otherwise. The final wrench pass must still follow the exact application sequence and calibrated range.
Installation procedure and verification
Apply the specified threadlocker, position the documented face toward the transmission and hand-start all six bolts without using them to overcome a misaligned register.
Tighten 1-4-2-5-3-6 at 20 N-m, repeat at 50 N-m, then repeat at 100 N-m. Inspect seating after every pass.
Mistakes that cause repeat failures
- Losing original flywheel direction
- Skipping either preliminary pass
- Using final torque on converter bolts
- Substituting oily threads for specified threadlocker
- Forcing an offset bolt pattern
Flywheel, flexplate and converter are separate joints
The crank bolts clamp the flywheel or flexplate to the crankshaft. Pressure-plate bolts clamp a clutch cover to a manual flywheel, while converter bolts connect an automatic flexplate to the torque converter. These fasteners commonly have different sizes, grades, thread treatments and torque values.
Never use the crank-flange torque for converter or pressure-plate bolts. Confirm converter seating before drawing the transmission to the engine; bellhousing bolts must not be used to force a gap closed.
Final installation checklist
- Correct balance and tooth count confirmed
- Orientation marks and crank register aligned
- New bolts/clamp ring used where required
- Mating faces clean and dry
- Specified thread treatment applied only to threads
- All bolts hand-started
- Staged opposite-side sequence completed
- Runout and pilot/bellhousing alignment checked
- Converter fully seated or clutch centered
- Engine rotates freely by hand
Chevrolet Chevy LS1 5.7L specifications can change by model year, engine, platform, wheel, and installed component. Confirm the VIN or engine identity, part numbers, fastener condition, and the current manufacturer instructions before service.
Chevy LS1 Flywheel Torque Sequence Diagram FAQs
What is LS1 flywheel bolt torque?+
The cited GM process is 20 N-m, 50 N-m, then 100 N-m (74 lb-ft final), each in sequence.
Does the LS1 flywheel use a locating pin?+
GM states that the cited flywheel does not use a locating pin, so its original position/direction should be recorded.
Should flywheel bolts be tightened in a star pattern?+
Use the exact numbered factory figure when available. An opposite-side or crisscross staged pattern is the safe controller for a matching circular flange because it seats the part evenly.
Can flywheel bolts be reused?+
Only if the exact service manual and fastener instructions permit reuse. Torque-to-yield, coated single-use or damaged fasteners must be replaced.
Is flywheel bolt torque the same as converter bolt torque?+
No. They are separate joints with different fasteners and specifications.
Technical sources
TorqueSheet favors engine- and component-specific manufacturer instructions over unsourced universal values.
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