Purpose and theory (short)
- The flexplate is the thin, discoid coupling between the engine crankshaft and the automatic transmission’s torque converter. It transmits engine torque to the torque converter, provides a ring gear for the starter, and is designed to flex slightly to absorb torsional vibration. Think of it like a springy bicycle sprocket that bolts to the crank and drives the rear hub (the torque converter) — if it cracks, warps, or loses teeth, the engine will not drive the transmission cleanly and the starter may not engage correctly.
- Repairing/replacing the flexplate is needed when you see vibration, starter grinding, starter engagement misalignment, slapping noises, visible cracks, missing/chipped ring-gear teeth, or failed bolts. Left unaddressed, a failed flexplate can cause transmission pump damage, lost drive, or catastrophic separation of engine and transmission.

System components and what each does (every relevant component)
- Engine crankshaft flange: the machined end of the crank. It provides bolt holes (and sometimes dowel pins) for the flexplate to locate against. The fit must be clean and true.
- Dowel pins / locating pins: small hardened pins in the crank or block that index the flexplate so it sits exactly concentric to the crank.
- Flexplate: thin stamped or machined disc with: central bolt hole pattern to attach to crank/dowel pins; balancing weights; the ring gear pressed around the outside edge for starter engagement; holes for torque converter bolts (on automatics) or flywheel-to-clutch parts on manuals. It flexes slightly to absorb torsional shock.
- Ring gear (on flexplate): the outer-toothed ring the starter pinion engages. Press-fit into the flexplate.
- Torque converter: splined/hubbed round assembly that slides onto the transmission input and bolts to the flexplate. It transfers torque hydraulically and must be properly seated on the transmission pump before flexplate bolts are tightened.
- Torque converter-to-flexplate bolts: short, high-grade bolts that fasten the converter to the flexplate. They must be correct grade, length, and torqued to spec; often used with threadlocker.
- Starter motor & starter pinion: starter pinion engages the flexplate ring gear to crank the engine. Alignment to the ring gear must be correct.
- Bellhousing / transmission housing: surrounds the torque converter/crank interface and bolts to the engine; provides access holes to reach converter bolts on some models.
- Transmission input pump/mount: the torque converter must be fully seated into the transmission pump and engage the input shaft splines; if not, you can damage the pump or torque converter hub.
- Bolts, washers, threadlocker: high-strength fasteners used to secure the flexplate and torque converter.

Tools and consumables required
- Full metric socket set (including deep sockets), breaker bar, ratchet
- Torque wrench (capable of required torque range), impact gun optional but use carefully on flexplate bolts
- Transmission jack or heavy-duty floor jack and support blocks
- Engine support bar or engine hoist/mooring strap if you must separate engine/transmission mounts
- Vehicle lift or good jackstands and wheel chocks
- Screwdrivers, pry bars, alignment punch
- Dial indicator with magnetic base (for runout check)
- Feeler gauge, paint marker or scribe for indexing marks
- Penetrating oil, parts cleaner, lint-free rags
- Threadlocker (medium strength, e.g., Loctite 243) if specified by manufacturer
- Replacement flexplate and correct replacement bolts; replacement torque converter bolts if required; new ring gear only if included with flexplate
- Safety: safety glasses, gloves, ear protection

Safety first
- Disconnect battery negative terminal before starting.
- Use jackstands or a lift — never rely on a jack alone. Secure truck on level ground.
- Support the transmission with a jack to avoid sudden droop when you loosen bolts.
- When separating torque converter/engine, support the converter so it cannot hang on hoses.
- Heavy components: use helpers or a hoist.

Preparation and diagnosis
- Symptoms that indicate flexplate service: pronounced driveline vibration at idle/under load; starter grinding or inconsistent cranking; clunking when shifting; visible flexplate cracks or missing ring-gear teeth.
- Visually inspect (with bellhousing removed or through inspection hole): ring gear tooth damage, hairline cracks radiating from bolt holes, rusted or loose bolts, discoloration indicating overheating, deformation or bends.
- If vibration is present, mount a dial indicator on the crank or flexplate and measure runout at the ring gear location. Any runout beyond manufacturer spec (or if perceptible by feel, >0.5 mm) means replace. Also check for flex at bolt holes.

Step-by-step — removal (automatic transmission, typical Hino truck procedure)
Note: always follow the official Hino GH1H workshop manual for exact lifting points, bolt counts, torque specs and sequences. The sequence below is the standard workflow.

1) Park, secure, and prepare
- Park on level ground, chock wheels, disconnect battery negative.
- Raise vehicle and support on jackstands or use a lift. Ensure safe access to bellhousing and starter.

2) Remove ancillary components
- Remove starter motor (unbolt electrical cables and mounting bolts). Label cables.
- Remove any skid plates, shields, or driveshafts obstructing access.
- If accessible, inspect ring gear through starter hole for damage.

3) Support transmission and engine
- Place a transmission jack under the transmission to support its weight.
- If you will separate engine mounts, provide engine support (engine hoist or support bar) to keep engine from tipping.

4) Access torque converter-to-flexplate bolts
- In many Hino trucks you can remove bolts through bellhousing access holes; on some you need to separate transmission from engine to access all bolts. If bolts are accessible, rotate engine by turning crank with a socket so each converter bolt lines up with an access hole.
- Apply penetrating oil and allow to soak.

5) Remove torque converter-to-flexplate bolts
- Carefully remove bolts in a progressive sequence (loosen then remove). Support the torque converter so it does not pull away. Keep track of bolt orientation and holes — count and mark positions.

6) Mark positions
- Using a paint marker, mark the flexplate-to-crank orientation and mark torque converter if needed. This helps ensure correct indexing.

7) Remove bellhousing-to-engine bolts (if separating)
- Remove bellhousing bolts while transmission is supported by its jack. Slowly slide transmission back until torque converter disengages from pump and can be supported by jack—do not let it drop.

8) Remove flexplate
- If torque converter is still bolted and you have separated the transmission, remove flexplate-to-crank bolts and pull flexplate forward off dowels. If you removed converter first, you can now unbolt flexplate from crank and remove.
- Inspect thread condition in crank flange; clean any debris.

Inspection (detailed)
- Flexplate: look for cracks emanating from bolt holes, missing or chipped ring teeth, heat discoloration, bending or warping, damaged balancing weights, worn mounting holes. Any cracking or heat-coloration = replace.
- Ring gear: check for broken/flattened teeth or excessive wear pattern.
- Crank flange faces: check for nicks, corrosion; clean and file smooth minor burrs; ensure dowel pins in good condition and tight.
- Converter hub face: check for wear or damage where it mates to flexplate.
- Bolts and threads: replace bolts if length is stretched, shank is scored, or threads damaged. Apply thread chaser to threads in crank only if required and undamaged.

Installation — general principles
- Never reuse flexplate bolts unless they are factory-specified reusable grade and in good condition; torque converter-to-flexplate bolts are critical fasteners.
- Use correct bolt grade and length; some require threadlocker.
- The torque converter must be fully seated on the transmission pump and input hub before any flexplate/bolts are tightened. If converter is not seated and you torque bolts, you will pull converter forward and possibly damage the pump or impeller.
- Tighten bolts in a star/progressive sequence to prevent distortion.

Step-by-step — installation
1) Clean mating surfaces
- Clean crank flange and torque converter mating face with solvent; do not leave oil/grease on bolt threads.

2) Seat the torque converter on transmission
- If transmission is back under the engine, push the transmission forward until torque converter engages pump and the converter hub engages splines. You should feel/snap the converter into position. Rotate converter while pushing until it drops fully home. Check that converter studs/bosses line up to flexplate bolt pattern — a properly seated converter will allow bolts to start without having to pull converter forward.

3) Fit flexplate to crank
- Install flexplate onto dowel pins and hand-thread bolts into crank. Use new bolts or ones cleaned and inspected. Start all bolts by hand to ensure threads engage true.

4) Torque flexplate-to-crank bolts
- Using the specified torque sequence (typically star pattern), tighten bolts gradually in stages to the manufacturer torque. If the workshop manual calls for threadlocker or locking washers, apply exactly as specified.

5) Bolt torque converter to flexplate
- Turn the crank to align converter bolt holes if necessary. Start bolts, apply threadlocker if specified, and tighten in a criss-cross pattern to the specified torque in stages. Usually you do the bolts in 3–4 passes evenly.

6) Check runout and final checks
- Rotate the assembly by hand to make sure there is no interference, catch, or binding. Check that starter engages freely and does not grind.
- Reinstall starter and any shields, reconnect wiring, reinstall driveshaft if removed.
- Lower vehicle, reconnect battery, and run engine at idle while parked to listen for abnormal noises. Check for vibration, leaks, and starter engagement. Road test gradually to confirm.

Measurements and tolerance checks
- Runout: measure with dial indicator against flexplate face or ring gear. Compare to factory spec. If beyond spec, replace.
- Bolt torque: use the workshop manual values. If values are unknown, do not guess — incorrect torque is a frequent cause of failure.

What can go wrong (and how to avoid it)
- Incorrect bolt torque or sequence → bolt failure, loosening, or flexplate distortion. Avoid by using torque wrench and correct sequence.
- Thread damage in crank flange → stripped threads cause bolts to loosen or fail. Avoid by installing correct bolts and using proper torque; repair with helicoil only per manual and with crank removed if necessary.
- Torque converter not fully seated → damage to transmission pump, converter hub, or inability to start. Always ensure full seating before tightening.
- Reusing damaged bolts → risk of stretched or broken bolts. Replace bolts if in doubt.
- Starter misalignment due to deformed ring gear or incorrect flexplate seating → starter grinding. Replace flexplate or adjust starter if housing permits.
- Cracked flexplate missed at inspection → catastrophic failure: parts break loose, can damage bellhousing, transmission, or engine components. Replace on any visible crack.
- Ring gear slipping or pressed-in gear loose → starter engagement poor. Replace flexplate.

Practical tips (workshop-style)
- Mark the orientation of the old flexplate before removing so you can compare balance orientation.
- Count torque converter bolts and make sure none are missing — losing one can overstress remaining bolts.
- Keep a clean workspace; contamination between mating faces can hide seating errors.
- If you need to remove the crankshaft rear oil seal or repair threads, do that with the transmission off and follow service manual.
- Always use the correct grade bolts and replace any bolts that were stretched or failed.
- If in doubt about runout or balance, replace the flexplate — flexplates are inexpensive relative to potential transmission damage.

Testing after repair
- Start engine and observe starter engagement and cranking sound.
- Idle and then apply light throttle; listen for abnormal knocks, clunks, or vibration.
- Road test at low speed, vary throttle and shifts to check for driveline vibration or slippage.
- After 50–100 km, recheck torque of accessible bolts per manual service interval (some manufacturers require re-torque after initial operation).

Final note
- The Hino Super F Series GH1H will have specific bolt torque values, bolt counts, and service limits; use the Hino workshop manual for those exact specs and sequences. Follow safety and torque instructions precisely — the flexplate/transmission interface is a safety-critical, high-load area.

This covers the components, why the repair is needed, how the system works, and step‑by‑step removal/installation and inspection procedures tailored for a beginner mechanic working on a Hino automatic flexplate replacement.
rteeqp73

truck wont build air - - quick fix - - freeing up stuck unloader valve on compressor. that caused the truck to not build air pressure.

4WD Hino 1528 GT - Quick Off Road Test and Review 0:00 Intro 0:50 Overview 1:20 Test Drive 3:30 Water Crossing 4:00 Conclusion The four wheel drive Hino is now available in Auto ...

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