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Toyota B 2B engine factory workshop and repair manual digital

Below is a practical, step‑by‑step beginner‑friendly guide to reconditioning (rebuilding) a manual gearbox/transmission on a Toyota “B” (2B) application. I’ll explain the theory, how it works, describe every common component you’ll encounter, list tools and checks, and walk you through disassembly, inspection, repair, reassembly, and testing. Where exact numbers (torques, clearances) are needed I’ll tell you to use the factory workshop manual because those values vary by model — but I’ll give practical methods and typical ranges so you know what to measure and how to interpret results.

Quick analogies up front
- Gears are like bicycle sprockets and the chain: different sized cogs give different speeds/torques.
- Synchros are like a matchmaker that brings two rotating parts to the same speed so they can mesh smoothly.
- Bearings are the smooth rollers/hubs that let shafts spin like the wheels on a shopping cart.
- The gearbox housing is the box that keeps everything in alignment and filled with oil — like a gearbox “home”.

Why recondition a gearbox (theory of failure)
- Normal wear: teeth wear, synchro rings wear, bearings develop play.
- Oil problems: contamination, low level, or wrong oil accelerates wear.
- Overload/misuse: grinding gears, clutch slippage, or shock loads chip teeth or damage bearings.
- Leaks: seals fail and allow oil loss; running low destroys bearings and synchros.
- Symptoms: whining or growling (bearings), gear rattle at speed (backlash), grinding when shifting (synchros), gears popping out, oil leaks, burnt smell.

Main components — detailed descriptions
1. Gearbox housing (case)
- Cast aluminium or steel body. Holds oil, supports and locates bearings and shafts, and attaches to engine and chassis. Surfaces have bearing seats and machined faces for covers and gaskets.

2. Input shaft
- Receives torque from the clutch/engine. Has a splined end for the clutch hub and splines for engaging gears or coupling to the layshaft/countershaft arrangement.

3. Layshaft / Countershaft
- Carries the gears that mesh with the gears on the main/output shaft. Typically all layshaft gears are always meshed (constant mesh) with the mainshaft gears. Like the middle row of gears in a bicycle hub.

4. Main/output shaft
- Takes torque out to the driveshaft or prop-shaft. Contains the sliding dog hubs or synchronizer assemblies that select gears.

5. Gears (various ratios)
- Fixed on shafts, sometimes free-spinning on the mainshaft until a hub/synchro locks them to the shaft. Gear teeth transfer torque at different ratios; they must run with correct tooth contact pattern.

6. Synchronizer assemblies (synchro rings, hubs, sleeves, keys)
- Cone friction rings (brass/steel) that match rotational speeds before engagement; hubs and sliding sleeves lock the gear to the shaft. If worn, you’ll get grinding.

7. Shift forks and shift rail/drum
- Mechanical linkage moved by the shift lever. Forks slide the synchro sleeves to select gears. Shift rails must be straight and forks’ pads should not be worn or bent.

8. Bearings (tapered roller, ball, roller)
- Support shafts and control endfloat and radial clearance. Worn bearings produce noise and rough running.

9. Seals and gaskets
- Keep oil in and contamination out. Commonly output shaft seal, front input seal, and case gaskets.

10. Reverse idler gear
- Reverses direction to get reverse gear; engages only for reverse.

11. Speedometer drive and auxiliary parts
- Small gear/drive assembly for speedometer; inspect and replace seal if needed.

12. Shims and spacers
- Thin washers that set bearing preload and endfloat (axial clearance) and gear mesh. Critical for correct fit.

13. Fasteners, plugs, fillers, drain plug, oil pick-ups (if present)
- Clean and torque correctly; replace crush washers if present.

Tools and supplies you’ll need
- Service/repair manual for your specific model (absolute must for specs).
- Basic hand tools (sockets, wrenches, screwdrivers).
- Torque wrench.
- Hydraulic press or arbor press (for bearing removal/installation).
- Bearing pullers / gear pullers.
- Snap ring pliers.
- Feeler gauges, feeler blades.
- Dial indicator (for measuring endfloat/backlash).
- Vernier caliper and micrometer.
- Gear marking compound (Prussian blue or special paint).
- Clean parts trays and magnetic trays to keep small parts.
- Solvent parts washer or degreaser and compressed air (caution).
- New bearings, synchro rings, seals, gaskets, shims, and any worn gears.
- High quality gear oil to the correct grade.
- Shop rags, safety glasses, gloves.

Preparation and safety
- Work on a clean bench with good lighting. Keep the environment dust-free.
- Label and photograph parts/positions as you disassemble. Mark orientation.
- Wear safety glasses and gloves. Be careful with solvent and compressed air.
- Put drained oil into a sealed container for disposal per local rules.

Disassembly procedures (overview, step-by-step)
1. Remove gearbox from vehicle
- Disconnect driveshaft/propshaft, linkages, and mounting bolts.
- Support engine/transmission appropriately. Drain gearbox oil, remove filler and drain plugs.

2. External components off
- Remove speedometer drive, shift lever linkage, clutch release components as needed.

3. Open the case
- Remove case bolts and separate halves (or remove cover plate). Keep bolts in order and note any dowels/shims.

4. Remove selector assembly and forks
- Take off shift rails/drum and carefully withdraw shift forks. Mark which fork goes to which gear and its orientation.

5. Remove shafts
- Extract mainshaft and layshaft as assembly; note positions of gears and synchronizers. Slide off gears one by one, keeping the stack order.

6. Remove bearings and seals
- Use press or pullers to remove bearings, races, and seals. Keep track of shims and spacers.

Inspection — what to look for and how to measure
Clean everything with solvent before inspection.

Gears
- Visual: Look for chipped teeth, pitting, scoring, heavy wear at tooth faces, or discoloration (overheat).
- Use magnifier: surface fatigue (micro-pitting).
- Measure for play and ovality with calipers.
- Gear tooth surface pattern: use gear marking compound to check contact pattern when assembled — pattern should be centered on the tooth face, not too close to tip or root. Off-center pattern => wrong shim or worn mating gear.

Bearings
- Inspect rollers and races for brinelling (indentations), pitting, discoloration, spalling.
- Spin by hand: feel for roughness or binding. Excess play or noise = replace.
- Tapered bearings: check clearances and cone/taper condition.

Synchronizers
- Check friction surfaces for glazing, burning, heavy wear or broken keys/sprags.
- Brass rings typically show wear at the cone surface; if teeth are rounded the engagement will be inadequate.
- Check for grooves or missing teeth in the dog teeth — if rounded, they must be replaced.

Shafts
- Check splines for wear and fatigue; measure journal diameters with micrometer; look for scoring.
- Check for straightness (roll on V-blocks).

Shift forks & rails
- Check for bend, worn pads, and wear on contact points. Thin pads or bent forks cause misshifts.

Seals, gaskets
- Replace all seals and gaskets during reassembly.

Measurements and setting clearances (the critical bits)
- Endfloat (axial play) of the mainshaft: measured with dial indicator; typical target is small (often 0.05–0.2 mm) — check the manual.
- Bearing preload (if tapered bearings): set with shims or nut torque per manual; incorrect preload kills bearings.
- Gear backlash: measured between gear pairs, usually a few thousandths of an inch (0.05–0.2 mm) depending on gearbox. Measured with feeler gauges/dial indicator. Use shims to adjust.
- Gear tooth contact pattern: use marking compound, rotate to check. Adjust shim/endfloat until contact is centered across face width and length.
- Synchro clearance: measure free travel on the sleeve and inspect keys/slots. Too much clearance => poor engagement.

Typical wear criteria (replace if)
- Bearings: any noise, roughness, or visible race/roller damage.
- Synchro rings: worn/beveled cones, less than 50% of original thickness at friction area.
- Gear teeth: cracked, chipped, or heavy pitting/surface fatigue.
- Shafts: splines thinned, seized parts, or bent shafts.
- Shift forks: bent or worn beyond service limits.

Repair/replacement
- Replace all bearings, seals, and worn synchros as a kit where possible. Bearings are inexpensive relative to failure risk.
- Replace any gears with chipped teeth or heavy pitting.
- Reuse gears only if tooth surfaces, splines, and bores are within specifications.
- Resurface or replace shift forks if worn. New forks often recommended with synchronization kits.

Assembly — best practice
1. Clean and pre-lubricate
- Re-clean all parts. Use assembly lube on bearings, shafts and synchro cones during assembly.

2. Fit bearings and races using a press and correct drivers.
- Do not hammer directly on bearing races or press at wrong surfaces — use proper tools.

3. Reassemble layshaft and mainshaft with new bearings, shims, and synchros in original order.
- Replace all circlips/snap rings that deform and never reuse stretch bolts if present.

4. Set shims and endfloat
- Fit shims per manual or use iterative measurement: assemble mainshaft into case, fit bearing preload shims, tighten and measure axial clearance, adjust with shims until specified endfloat is achieved.

5. Set backlash and tooth contact
- Use dial indicator and trial shims; then apply gear marking compound, rotate under light load, and inspect the contact. Move shim to center the pattern. Repeat until pattern is correct.

6. Install shift forks/rails and check neutral engagement and gear selection.
- Ensure forks move freely, and that gears engage fully without binding.

7. Replace case gaskets and seals
- Use new gaskets, torque bolts to spec in correct sequence.

8. Fill with correct gear oil to the specified level and spec.
- Use the oil grade recommended by Toyota for that gearbox (e.g., GL-4 or GL-5 and viscosity as manual states).

Testing and run-in
- Bench test shift through gears of installed gearbox before vehicle installation: check for smooth engagement, no binding, correct neutral detent positions.
- Reinstall gearbox, reconnect linkages, align clutch properly.
- Road test: start in a safe area, test quiet idle, then accelerate and shift through all gears under light load. Listen for noises and check for leaks.
- After initial run (first 100–500 km), re-check oil level and check for leaks. Re-torque bolts if manual specifies.

Common things that go wrong and how to avoid/correct them
- Wrong shim/backlash: leads to noisy gear, premature wear. Fix: measure and adjust shims as described, re-check contact pattern.
- Incorrect bearing preload: leads to heavy load or looseness; use manual’s shimming procedures or preload nuts.
- Reusing worn synchros: causes grinding and short life — replace worn rings.
- Mixed-up parts (forks/gear order): mark everything and photograph; incorrect orientation can cause impossible shifting.
- Contaminated reassembly: dirt introduces wear; work clean, use lint-free cloths and filtered oil.
- Improper torque on bolts: case distortion leads to misalignment; follow torque sequences.
- Over-tightening seals: can deform housing and cause leaks or misalignment.

Final tips / checklist before you call it done
- Replace all seals, gaskets, and fasteners as required.
- Replace front and rear oil seals even if they look okay (cheap insurance).
- Install new bearings and synchromesh as a set where possible.
- Record parts replaced and torque/clearances set for future reference.
- Keep a service manual handy and follow its procedures for spec values.

If you need a short checklist summary:
1. Drain oil, remove gearbox, clean, photograph/label.
2. Disassemble, remove shafts, extract bearings/synchros.
3. Clean and inspect every part; replace damaged parts.
4. Measure endfloat, backlash, and contact pattern; adjust with shims.
5. Fit new bearings/seals, reassemble, torque to spec.
6. Fill with correct oil and run/test.

That’s the full workflow for reconditioning a Toyota manual gearbox. Use the vehicle’s factory workshop manual for exact torques and clearance specs for the 2B application — the procedures above tell you what to do and why, and how to check each critical item so the gearbox will be quiet, smooth, and durable.
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