Tools & consumables
- Basic hand tools: metric deep & shallow sockets (8–22 mm typically), ratchet, extensions, universal joint, breaker bar.
- Torque wrench (capable to required torque range, e.g., 5–150 Nm / 4–110 ft‑lb).
- Oil drain pan, drain funnel, disposable rags.
- Floor jack + quality jack stands (rated for vehicle weight) or a workshop 2-post/4-post lift.
- Engine support bar or transmission jack (if engine/transmission needs support / slight droop).
- Gasket scraper or plastic razor blade, wire brush, brake cleaner / parts cleaner.
- Sealant: Hino-approved RTV or anaerobic sealant if specified by manual.
- New oil pan gasket (OEM or specified replacement); new oil drain plug crush washer.
- New oil filter and engine oil (spec & capacity per manual).
- Thread chaser / tap & die (light), bolt cleaner, anti-seize (if specified), thread locker (if specified).
- Flashlight, magnetic tray, protective gloves, eye protection.
- Optional: impact gun (careful), drip tray, inspection mirror.

Safety precautions (must do)
- Work on a level surface. Chock rear wheels and set parking brake.
- Disconnect negative battery terminal to prevent accidental cranking.
- Support vehicle securely: never rely on a jack alone. Use jack stands or a lift.
- Support engine/transmission if oil pan removal requires engine movement; do not let engine hang on mounts.
- Wear gloves and eye protection. Clean spills immediately to avoid slip hazards.
- Dispose of used oil and filter to local regulations.

Replacement parts commonly required
- Oil pan gasket (OEM part for your Hino FD/FE/FF/SG/FA/FB engine).
- Oil drain plug crush washer/washer.
- Engine oil filter.
- Engine oil (correct type & quantity per manual).
- Oil pickup O‑ring/gasket (inspect; replace if deformed).
- Oil pan bolts (replace if bolts are one‑time stretch bolts—check manual).
- RTV/sealant (if specified).

Step‑by‑step procedure (general Hino medium-duty diesel engine approach)
1. Preparation
- Park on level surface, chock wheels, apply parking brake, disconnect battery negative.
- Raise vehicle using lift or floor jack; support on jack stands at the manufacturer‑recommended jacking points so you have clear access to oil pan.
- Place oil drain pan under oil drain plug.

2. Drain engine oil & remove oil filter
- Remove drain plug, allow oil to drain fully. Remove oil filter to drain residual oil from filter housing.
- Replace drain plug washer; loosely refit drain plug if you’ll reinstall before refilling (or leave out until final). Clean drain plug and magnet.

3. Gain access & remove obstructions
- Remove any components blocking oil pan removal: splash shields, crossmember(s), engine undercover, steering linkage, front exhaust pipes heat shields, wiring harness brackets, or identifiably interfering brackets. On some Hino engines you may need to remove the steering gear crossmember or lower front engine mount.
- If necessary, support the engine with an engine support bar or support the transmission with a jack and block of wood so the weight is not on the mounts when components are loosened.

4. Loosen and remove oil pan bolts
- Loosen bolts in a crisscross pattern to relieve stress evenly; many oil pans are sealed with RTV and bolts can be tight—use breaker bar or impact carefully.
- Keep bolts organized by location (different lengths). Some bolts are longer and have washers or collars—do not mix.

5. Separate pan from block
- Pry lightly at corners with a plastic scraper or flat blade; do not gouge the mating surfaces.
- If RTV bead is cured, cut sealant with gasket scraper evenly around. Have drain pan handy—oil will spill when pan separates.
- Lower the pan slowly; watch for oil and pickup interference. If pickup strikes pan, support pickup/pipe.

6. Inspect pickup, screen, and mating surfaces
- Remove oil pickup/strainer if needed (clean screen; replace pickup gasket/O‑ring if worn).
- Inspect oil pump pick‑up, screen, and oil passages for sludge or metal debris. If heavy sludge or metal, investigate further (bearing failure).
- Inspect oil pan for damage, cracks, warped flanges, or excessive scoring; replace pan if damaged.

7. Clean surfaces
- Clean mating surfaces on block and pan thoroughly with scraper and parts cleaner; remove all old gasket/RTV residue.
- Use wire brush or thread chaser to clean bolt holes; blow out with compressed air (wear eye protection).
- Ensure oil passages to bolt holes remain clean.

8. Prepare new gasket / sealant
- Fit new gasket per manufacturer instructions. Some Hino models use a full gasket; others require a bead of RTV at specified locations and a paper gasket elsewhere. Apply sealant sparingly where specified; do not smother mating surfaces.
- If using RTV, wait per product instructions before tightening (normally no cure time required for assembly, but some procedures call for tack cure—follow manual).

9. Refit oil pan
- Position pan carefully, align oil pickup and bolt holes, insert bolts finger‑tight in correct locations to hold pan.
- Tighten bolts in crisscross pattern gradually in steps to final torque. Use torque wrench for final passes.
- Important: follow Hino workshop manual torque values and sequence. If manual calls for torque-to-yield bolts or special tightening procedure (staged torques, angle tightening), follow exactly.

10. Reinstall removed components
- Refit crossmembers, mounts, splash shields, exhaust parts, wiring brackets; torque bolts to spec.
- Reinstall oil filter (new filter) and drain plug with new crush washer torqued to spec.

11. Refill with oil & check
- Reconnect battery negative.
- Refill engine with correct oil type and quantity per manual.
- Start engine and check for leaks. Run to normal temperature; recheck leak and oil level after shutdown and settle, re-torque bolts if manual requires post-heat torque.

How the key tools are used
- Torque wrench: set to specified torque and tighten bolts in the specified sequence. Use incremental tightening (e.g., hand → 50% → 100% of torque). Hold wrench square to bolt; do not jerk. For angle torquing, use proper angle gauge.
- Engine support / transmission jack: place under oil pan support points or transmission crossmember, lift slightly to support weight before removing mounts; move slowly and keep stable.
- Gasket scraper/plastic razor: remove old gasket material without gouging metal. Use plastic first, then thin metal scraper at very shallow angle only if necessary.
- Thread chaser: clean bolt threads and tapped holes carefully; do not use aggressive taps that remove or weaken threads.
- Impact gun: use for stubborn bolts only; final tightening must always be with torque wrench.

Common pitfalls & how to avoid them
- Not supporting the engine/transmission: can cause mount/bolt misalignment or dropped components—support before loosening mounts.
- Mixing bolts: oil pan bolts have different lengths/shoulders—label and reinstall in original positions.
- Damaging mating surface: gouging pan or block flange leads to leaks—use plastic scrapers and clean gently.
- Incorrect sealant/gasket technique: using excessive RTV or wrong sealant causes blockage or leaks—use OEM gasket and follow manual.
- Overtorquing or undertorquing: causes warping or leaks—use torque wrench and correct sequence.
- Reusing stretch bolts or damaged bolts: replace as specified.
- Not replacing drain plug crush washer: causes slow leaks.
- Not inspecting pickup/screen: sludge or debris can cause oil starvation; clean or replace when in doubt.
- Reusing a warped pan: will leak; replace.

Final notes
- Always cross‑check every bolt torque and follow the exact Hino workshop manual procedure for your engine code (Hino factory specs override generic guidance).
- If heavy metal debris is found in the pan, do not reassemble and run the engine — investigate bearings/pump.

Follow these steps and safety precautions exactly.
rteeqp73

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Sistema de Frenos Desarmado y armado del sistema de frenos. Instructor: Carlos Castillo.

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Scope and tone: concise, workshop-style step‑by‑step for a beginner mechanic. This covers theory, every internal component of a typical Hino FD/FE/FF/SG/FA/FB series manual transmission (long‑haul truck transmissions of that family use typical fully synchronized multi‑speed layouts), what goes wrong, and how to repair it. For exact torque values, shim thickness classes and final service specifications always use the Hino workshop manual for your model/year — those values are critical.

1) Theory — what a manual transmission does (simple analogy)
- Purpose: convert engine speed/torque to appropriate wheel speed/torque by selecting gear ratios. Analogy: it’s like a bicycle gearbox where you choose a different sized sprocket to make pedaling harder or easier.
- Components interact to transfer rotation from the input shaft (from the clutch) through fixed and rotating gears to the output shaft, while allowing the gears to spin freely when not engaged.
- Synchronizers match speeds of shafts before metal dog teeth engage so you don’t grind gears — think of synchronizers as little cone clutches that “rub” the two parts to the same speed before they lock together.

2) Major components — what they are and what they do
(Describe every component you’ll encounter inside the case)

- Bellhousing/case halves: two halves that enclose all internals; mounts to engine. Contains oil passages, dowel pins, and bolt holes.
- Input shaft (primary shaft): connected to clutch/driver plate; carries input gear(s) and is supported by bearings in the case. Receives rotational energy from the engine.
- Mainshaft (output shaft / countershaft depending on layout): shaft that carries the gears that ultimately send rotation to the driveshaft. In many Hino transmissions the mainshaft is the output; there’s also a counter/ layshaft.
- Layshaft / countershaft: carries a set of gears permanently meshed with gears on the mainshaft. It is an idler that provides the different ratios (fixed gear sets).
- Gears (helical or straight): gear wheels of different sizes mounted on shafts. Helical for quieter operation. Gears on layshaft mesh with gears on mainshaft to produce ratios.
- Sliding gears (on mainshaft) and gear hubs: some gears slide or are part of hub assemblies to engage with synchronizers.
- Synchronizer assemblies (synchro rings/baulk rings, hubs, sleeves): Baulk ring = friction ring (usually brass) with a cone face; hub = splined to the shaft; sleeve slides over hub to lock gear to shaft. Synchronizer’s job: friction to match speeds, then mechanical lock.
- Shift forks and selector rails (shift rails): forks engage the synchronizer sleeve and move it along the hub; rails guide forks.
- Shift drum/selector mechanism (if sequential) or selector forks (typical Hino uses sliding sleeves and selector forks controlled by lever linkage): converts lever movement to axial motion of forks.
- Detents and spring/ball system: provide positive position and resistance at each gear detent to prevent mis-selection.
- Bearings (roller, tapered, ball): support shafts, reduce friction. Tapered roller bearings are common for radial and axial loads.
- Bearing races (cups/cones): mating parts for bearings. Often replaceable.
- Seals and gaskets: oil seals, O‑rings and case gasket prevent leaks.
- Reverse idler gear and shaft (if separate): reverses direction of rotation for reverse gear.
- Speedometer drive/gear: driven by a gear on the output or layshaft to drive cable/sensor.
- Input pilot bearing / bushing: supports input shaft at bellhousing.
- Shift lever/selector linkage: external linkage to the driver; includes bushings that wear and affect gear selection.
- Fasteners, dowel pins, shims: maintain alignment and spacing (shims control endplay / backlash).
- Oil pump (if fitted inside transmission): circulates oil (some truck boxes rely on splash/ventilation).

3) Common failures — Symptoms and root causes
- Gear noise/whine at certain speeds: worn gear teeth, improper backlash, bearing wear, or hardened pitting on gear surfaces.
- Grinding on shifting (esp. into 1st/reverse): worn/damaged synchros (baulk rings), misadjusted clutch (not fully disengaging), bent shift forks, worn shift linkage.
- Slipping out of gear or popping into neutral: worn shift dogs, worn forks, worn hub/sleeve engagement, weak detents.
- Hard shifting or stiff lever: contaminated/old oil, worn bushings, misadjusted linkage, bent/damaged forks, seized bearings.
- Oil leaks: worn seals, damaged case surface, loose bolts, failed seal between case halves.
- Excessive endplay or axial movement: worn bearings, incorrect or missing shims.
- Internal metal in oil / catastrophic failure: broken teeth (from shock or fatigue), seized bearings that damage shafts/gear teeth.
- Vibration and harsh noise under load: broken/damaged gears, incorrect gear mesh, worn bearings.

4) Tools and preparation (safety first)
- Personal protective equipment: gloves, eye protection, steel‑toe boots, coveralls.
- Transmission jack or heavy-duty floor jack and stable stands; engine support or transmission crossmember support.
- Hand tools: sockets (metric), torque wrench, breaker bar, ratchets, screwdrivers, pliers.
- Specialty tools: bearing puller/gear puller, hydraulic press (for bearing/gear removal & installation), snap‑ring pliers, dial indicator with magnetic base (for backlash and endplay), feeler gauges, micrometer/inside micrometer, straight edge, soft mallet, seal driver set, pullers, drift punches, shim set, oil drain pan, parts cleaner.
- Consumables: clean rags, new gaskets/seals, Loctite if specified, new bearings/synchro rings/hubs as needed, Hino‑specified gear oil (consult manual — often API GL‑4 80W‑90 or 75W‑90; use model spec), assembly lube, anti‑seize.
- Clean, well lit workspace, labeled trays or bags for bolts, camera to photograph locations.

5) Diagnosis — narrow down the problem
- Road/idle test to reproduce symptoms. Note when: cold/hot, under load, in certain gears, at certain speeds.
- Check clutch adjustment / pedal free play first — many shifting problems are clutch related.
- Check linkage at shifter for play, worn bushings, binding.
- Check oil level and condition (metal shavings or smell of burnt oil).
- Listen with a stethoscope to bearings during road test or on bench. Grinding only when shifting → synchros; constant whine → gear tooth/worn bearings.
- If severe internal noise/metal in oil, remove transmission.

6) Removal from vehicle (overview)
- Park on level surface, chock wheels, disconnect battery.
- Raise vehicle safely, secure on stands.
- Drain transmission oil into clean container (save for inspection).
- Disconnect: driveshaft(s)/propeller shaft (mark orientation), speedo cable/sensor, shift linkage, clutch slave cylinder/actuator (drain/secure), engine/transmission mounts, wiring, exhaust if obstructing, crossmember.
- Support transmission with trans jack, remove bellhousing bolts and slide transmission back off input shaft. Remove carefully; some models heavy — need two-person lift.
- Inspect clutch, pilot bearing and flywheel face while trans removed. Replace those if worn (recommended when transmission is out).

7) Disassembly — organize and document
- Clean exterior before opening to avoid contaminating internals.
- Remove top cover (shift housing) and note the position of rails/forks/detents.
- Mark orientation and photograph assembly as you go. Label all small parts and bolts by location.
- Remove shift forks and rails first (careful with positioning and selector balls/springs).
- Remove snap rings and hubs; slide off synchronizer sleeves and rings.
- Extract mainshaft and layshaft assemblies. Use a press or gentle drift as needed. Remove bearings and races.
- Remove input shaft components (pilot bearing/bushing, seals).
- Keep bearings, races, gears and shafts grouped as assemblies so you can remember positions.
- Clean parts with solvent and dry thoroughly.

8) Inspection & measuring — what to check, tolerances concept
- Gears:
- Visually inspect for pitting, chipped or broken teeth, scoring, discoloration (overheating), or scuffing.
- Measure gear tooth profile wear; use contact pattern inspection or consult manual limits. Replace if teeth show spalling/pitting or excessive wear.
- Synchronizers:
- Baulk/cone ring: check friction surface thickness/profile. If the brass ring cone is rounded or worn beyond limit, replace.
- Hub and sleeve: check splines for wear, burrs, or elongation. Check keyways and locking features.
- Check that sleeves slide freely on hubs; binding indicates wear or score.
- Shafts:
- Inspect journals for scoring, heat marks; measure diameters with micrometer vs spec. Replace or regrind if out of tolerance.
- Bearings:
- Spin and feel; any roughness, noise, axial/radial play → replace. Check rollers and cages for pitting.
- Check bearing races for discoloration or spalling; replace paired cone/cup sets.
- Endplay and backlash:
- Using dial indicator, measure mainshaft endplay and gear backlash; compare to manual spec. Wrong backlash causes noise/gear damage.
- Seals/O‑rings:
- Check for distortion or cuts; replace as routine.
- Forks and rails:
- Check for bends, worn contact noses, and wear where forks contact the synchronizer hub. Bent forks must be replaced.
- Case:
- Check mating faces for cracks, flatness; check dowel pins and bolt holes for damage.

9) Replacement/repair tasks — practical steps
- Bearings & races:
- Press out bearings from shafts/housings. Clean bores and install new bearing races (heat case or freeze bearings if recommended), press new bearings to correct depth. Use proper drivers to avoid damaging seals or races.
- Synchro rebuild:
- Replace baulk rings, sleeves, hubs if worn. Synchro kits are typical replacements.
- Ensure cone surfaces are clean and free of burrs; slight lapping sometimes needed only with factory procedure.
- Shafts/gears:
- Replace damaged gears or entire shaft assembly if teeth or journals damaged. Replacing single large gear may be impractical.
- Seals:
- Install new seals with proper tool; do not drive seals cocked or damage lips.
- Shift forks:
- Replace bent or worn forks; where available fit new pads if designed.
- Shims and endplay:
- Reinstall shims to achieve correct bearing preload and endplay per manual. Use dial indicator to measure endplay and adjust shim thickness.
- Backlash setup:
- Use dial indicator to set backlash between specified gear pair. Adjust by changing pinion/shaft shims per manual.
- Assembly cleanliness:
- Use assembly lube on bearings and sliding surfaces during reassembly. Keep everything extremely clean — contamination kills gears/bearings quickly.

10) Reassembly — stepwise
- Install layshaft/countershaft assembly and gears with correct shims and bearings.
- Install mainshaft/gear assemblies and check rotation and mesh visually and by feel.
- Install synchronizers with new rings and sleeves; ensure tabs align properly with hub keys.
- Install shift forks and rails, confirm detents and selector balls/springs in place.
- Fit new case gasket or sealant if required and mate case halves carefully, ensuring no seals are pinched.
- Torque case bolts to spec in proper sequence. Use thread locker if required by manual.
- Set endplay/backlash per manual using shims; re-check after torquing bolts to spec.
- Verify smooth shift through all gears on bench; if any binding, disassemble and find interference.

11) Bench tests before reinstall
- Shift through all gears repeatedly to confirm positive engagement.
- Apply torque to input and rotate output; check for noise or binding.
- Recheck endplay and backlash.
- Check that synchronizers function (sleeve moves fully and locks).

12) Reinstall transmission and final checks
- Clean bellhousing mating surfaces; replace pilot bearing/bushing if worn.
- Mount transmission using jack; align input shaft through clutch and spline — use guide tool to prevent damage.
- Bolt to engine, torque bellhousing bolts to spec.
- Reconnect linkage, speedo, clutch hydraulic or cable, mounts, exhaust, electrical.
- Fill with Hino‑specified gear oil to correct level. Check for leaks.
- Adjust clutch free play and shift linkage per manual.
- Road test: shift through gearbox under load; listen for noise; test under acceleration/engine braking. Recheck oil level after initial run.

13) Common pitfalls & cautions (how things go wrong during repair)
- Not replacing bearings and synchros when worn — leads to early re-failure.
- Incorrect shim selection causing excess backlash (noisy gears) or too tight mesh (fast wear/heat, broken teeth).
- Reusing worn seals or gaskets — leads to leaks.
- Improper installation of bearings/races using hammering — can damage races and reduce life.
- Not checking or replacing pilot bearing or clutch components — will cause input shaft wobble and transmission damage.
- Contamination: dirt or stray tools left inside cause rapid wear.
- Using wrong gear oil (GL‑5 vs GL‑4) can damage synchros; many manual boxes require GL‑4. Use manufacturer spec.
- Not following torque sequence/values — case distortion, flange sealing issues.
- Improperly installed snap rings or using wrong ones — shafts can come apart under load.
- Forgetting to check/clean shift detents and return springs — leads to missed gears.

14) Symptom → likely fix quick reference
- Grinding into gear unless clutch depressed fully: clutch adjustment or bearing/pilot wear → check clutch first.
- Grinding only on upshift into gear at road speed: worn synchronizer cone/ring.
- Whine at constant speed, little/no load: gear tooth wear/mesh/backlash issue.
- Knock/clunk on engagement: worn or broken dog teeth, damaged hub, or worn detents.
- Oil on outside of case: case gasket or seal leak; inspect mating faces.

15) Final tips for a beginner mechanic
- Take many photos and label everything. One image can save hours.
- Work methodically: one sub‑assembly at a time. Use trays and labeled bags.
- Replace wear components (bearings, seals, synchros) rather than attempting partial fixes.
- If you don’t have a press, arrange workshop time or have a bearing shop press parts for you.
- If gear teeth, shafts or cases show severe damage, replacing the entire gearbox or core assembly may be the most economical and reliable option.
- Always consult and follow the Hino workshop manual for your exact model for torque specs, shim tables, and sequences.

Safety and liability note (brief): manual transmission repair involves heavy parts, presses, and critical measurements. Incorrect repair can cause dangerous failures. Follow shop safety, use proper tools, and consult factory manual for specs.

End — concise checklist to carry into the job
- Gather required tools, new parts (bearings, synchro kits, seals, gaskets), Hino manual.
- Diagnose and confirm gearbox needs internal work.
- Remove gearbox safely and clean exterior.
- Disassemble, photograph, and inspect all parts; replace worn items.
- Reassemble with correct shims/preloads, torque to spec, bench test.
- Reinstall, fill with correct oil, adjust linkage/clutch, road test, recheck.

No extra commentary.
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