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Two joints matter when you mate an engine and transmission: the flexplate to the crankshaft, and the torque converter to the flexplate. Get either wrong and you get grief. Under-torque the converter bolts and they walk loose — then the converter pilot pounds the flexplate until it cracks, or a bolt head shears and rattles around the bellhousing. Over-torque the flexplate-to-crank bolts and you can stretch or strip them, especially the torque-to-yield fasteners many modern engines use, which are one-time-use.
Every value below is in foot-pounds unless noted. Where an engine uses torque-to-yield (TTY) crank bolts, the manual gives an initial value plus an angle; the numbers here are the base service specs. Confirm your exact year and driveline in the FSM before final assembly.
Torque Converter-to-Flexplate Bolt Specs
These are the bolts you access through the starter opening or an inspection cover, turning the crank to bring each one up. Blue medium-strength threadlocker on clean, dry threads unless the manual says otherwise. Torque in a cross/star pattern in two passes, never one bolt to full spec then the next.
| Transmission | Converter Bolt Torque | Notes |
|---|---|---|
| GM 4L60E / 4L65E / 4L70E | ~44 ft-lb | 3 bolts, star pattern; threadlocker |
| GM 4L80E / 4L85E | ~44 ft-lb | 6 bolts; verify converter fully seated first |
| GM 6L80 / 6L90 | ~44 ft-lb | Blue threadlocker on clean threads |
| Ford 4R70W / 4R75W | ~23-35 ft-lb | Nut-style on some; check pilot engagement |
| Ford 6R80 / 6R140 | ~35 ft-lb | 6R140 diesel: heavier flexplate, verify seat |
| Dodge 68RFE / 48RE / 47RE | ~23 ft-lb (bolt), ~35 ft-lb (nut) | Confirm style; Cummins flexplate is heavy |
| Allison 1000 / 2000 | ~44 ft-lb | 6 bolts; flexplate has spacer/adapter |
| Chrysler 62TE | ~55 ft-lb | Transverse; access through inspection cover |
The number-one converter mistake: pulling the converter forward against the flexplate with the bolts instead of confirming it is fully seated into the pump first. If the converter is not fully home when you start the bolts, you load the pump, snap a bolt, or crack the flexplate on the first start. Seat the converter, confirm you have the correct converter-to-crank gap, then bring the bolts up evenly.
Flexplate-to-Crankshaft Bolt Specs
These bolts hold the flexplate to the crank flange. Many modern engines use torque-to-yield bolts that are single-use — replace them, do not reuse. Follow the FSM sequence and any angle-turn step.
| Engine / Platform | Flexplate-to-Crank Torque | Notes |
|---|---|---|
| GM LS / Gen III-IV V8 | ~74 ft-lb | Often TTY, one-time-use; check year |
| GM small/big block (older SBC/BBC) | ~60-65 ft-lb | Reusable grade-8; threadlocker |
| GM 6.6L Duramax | ~22 ft-lb + 45 deg + 45 deg (TTY) | Angle spec; new bolts |
| Ford Modular 4.6 / 5.4 / Coyote | ~59 ft-lb (varies by year) | Confirm FSM; some are angle-torqued |
| Ford 6.7L Power Stroke | Multi-step angle (TTY) | New bolts, follow FSM sequence |
| Dodge 5.9 / 6.7 Cummins | ~101 ft-lb | Heavy flexplate; grade-matched bolts |
| Chrysler Gen III Hemi | ~70 ft-lb | TTY on many; verify year |
Because these are so year-and-engine specific — and because getting a TTY spec wrong can send a flexplate through a bellhousing — treat the table as a starting reference and pull the exact value and angle from your factory manual before you final-torque.
Do It Right — Tools and Method
- Use a real click or digital torque wrench. "Good and tight" cracks flexplates. A 1/4"-3/8" click wrench covers converter bolts; a 1/2" covers crank bolts.
- Clean threads, correct threadlocker. Oil in a blind hole hydro-locks and gives a false torque reading. Chase the holes, wipe them, apply the specified threadlocker.
- Star/cross pattern, two passes. Snug all bolts, then final-torque in sequence so the converter or flexplate pulls up flat.
- Confirm converter seat before bolting. Push and rotate the converter until it drops into the pump; measure the gap to the flexplate against spec.
- Replace TTY bolts. Torque-to-yield fasteners stretch by design and lose clamp load if reused. New bolts every time.
- Recheck after break-in on a fresh build. On a performance or heavy-duty build, re-verify converter bolt torque after the first heat cycles.
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Shop Gearbox Insider →FAQ
What happens if converter bolts are too loose?
They back out. The converter pilot then hammers the flexplate, cracking it around the bolt holes, and a loose bolt head clatters in the bellhousing — a sound often mistaken for a rod knock. If you hear a rhythmic knock right after a trans install, pull the inspection cover and check those bolts before you do anything else.
Do I need thread locker on converter bolts?
Most manufacturers specify a medium-strength (blue) threadlocker on clean, dry threads unless the bolt comes with pre-applied patch adhesive. Never use red (high-strength) on converter bolts — you will fight them next time.
Can I reuse flexplate-to-crank bolts?
Only if they are conventional (non-TTY) bolts in good condition. Torque-to-yield bolts, common on Duramax, Power Stroke, and many late gas V8s, are single-use. Replace them.
Why torque in a star pattern?
To pull the converter or flexplate up flat and evenly. Fully torquing one bolt before the others cocks the part, induces runout, and can crack it or throw a vibration.