In 1990, development of a successor to the YJ began in Chrysler's "Jeep-Truck Engineering Pre-Program" department under Bob Sheaves and TJ program director, Craig Winn. Mules based on the YJ were built from 1990 to 1993, when formal approval was given for the TJ development program at a 0 million budget. From 1991 to 1992 designers worked at the new Chrysler Technical Center, building on various design proposals. In late 1992, Michael Santoro's TJ proposal was chosen by Tom Gale, Lee Iacocca, and executive management. In May 1993, now with engineering and supplier input, Santoro's final Wrangler production design was frozen at 32 months ahead of initial assembly. Verification prototypes using production bodies were built from early 1994 and tested through late 1995. As YJ production ceased in December 1995, the last pre-production TJ examples were assembled, with start of series of production in January 1996. Unveiled on January 2, 1996, at the 1996 Detroit Auto Show as an early 1997 model year introduction (1996 model year skipped), the TJ was an evolutionary update. It later arrived in Jeep showrooms in April 1996, after 6 years of overall investment and 36 month production development phase.Instead of leaf springs, this updated Wrangler featured a modern coil-spring suspension, front and rear, based on that of the Jeep Grand Cherokee, for better ride and handling, and a return to the classic CJ's round headlamps. The engine is the same 4.0 L AMC 242 Straight-6 used in the Cherokee and Grand Cherokee. A 2.5 L AMC 150 Inline-4 engine was available on entry-level models until 2002. The 2.4 L DOHC 4-cylinder engine previously used on the Chrysler PT Cruiser replaced it for 2003.A right hand drive version of the TJ was available for export markets, and was also offered for sale to U.S. rural route postal carriers. The version offered to U.S. postal carriers was only available with an automatic transmission.

In 1998 (MY1999), the fuel tank became standard at 19 U.S. gallons (72 L; 16 imp gal) capacity. There were some changes between the 2002 and 2003 years. From 1996 to 2002, the side door mirrors were black metal framed mirrors; and from 2003 to 2006 they were plastic molded mirrors. The fit of hard and soft tops is slightly different, and the fabric and colors available changed from 2001 to 2003. In 2002 (MY2003), the 3-speed automatic transmission was replaced with a 4-speed automatic with overdrive. The overdrive can be turned off with a dash switch. The radio bezels went from a rectangle in 2002 to a rounded-edged rectangle for 2003. The sound bar inside was changed to sound pods. The interior seats also changed design, going from a rounder model to one with a distinct separation between back and headrest areas. The standard skid plate was also revised for 2003 to make room for the Rubicon's bigger NV241OR transfer case. The change from the 30/32RH to the 42RLE also gained an additional skid plate. This version of the Wrangler is also notable for being the last production vehicle to use AMC-related parts. The AMC Straight-4 engine was retired after the 2002 model year, and both the AMC Straight-6 engine and the door handles (the latter of which first appeared on AMC vehicles in the 1968 model year) were retired along with this generation in 2006. Like the YJ Wrangler, the TJ Wrangler used both the AMC passenger car door handles as well as the larger door handles off the AMC-built Jeep CJ for higher-end models.

 

- **Understanding the Mass Airflow Sensor (MAF Sensor)**
- The MAF sensor measures the amount of air entering the engine. A faulty MAF sensor can lead to poor engine performance, reduced fuel efficiency, and increased emissions.

- **Tools Required**
- **Basic Socket Set**: A set of metric sockets (usually 10mm and 12mm) will be required to remove the sensor and any mounting bolts.
- *How to Use*: Attach the appropriate socket to a ratchet handle. Place the socket over the bolt head and turn counterclockwise to loosen.

- **Screwdriver (Flathead and Phillips)**: For any clips or covers that may need to be removed.
- *How to Use*: Use the flathead screwdriver for prying off plastic clips and the Phillips for screws. Turn counterclockwise to remove screws.

- **Wire Brush or Electrical Cleaner**: To clean the connector and sensor area.
- *How to Use*: If using a wire brush, gently scrub any dirt off the connector. If using electrical cleaner, spray it on the connector and wipe it clean.

- **Rags or Paper Towels**: For cleaning up and protecting surfaces.

- **Safety Glasses**: To protect your eyes while working.

- **Location of the MAF Sensor**
- The MAF sensor is typically located between the air filter box and the throttle body on the intake manifold.

- **Step-by-Step Replacement Procedure**
- **Safety First**: Disconnect the battery by removing the negative terminal with a socket. This prevents any electrical issues while working.

- **Locate the MAF Sensor**: Follow the air intake tube from the air filter to the sensor.

- **Remove the Air Intake Tube**:
- Use a screwdriver to loosen the clamps on both ends of the tube. Detach the tube from the air filter box and the throttle body.

- **Disconnect the MAF Sensor**:
- There will be a wiring connector on the MAF sensor. Press the tab and pull it out gently to disconnect it.

- **Remove the MAF Sensor**:
- Use the socket to remove the bolts securing the MAF sensor. Carefully take the sensor out.

- **Inspect the Sensor**:
- If the sensor is dirty or damaged, it should be replaced. Look for cracks or corrosion.

- **Cleaning the Sensor (if not replacing)**:
- If the sensor is still in good shape, use the wire brush or electrical cleaner to clean it gently. Allow it to dry completely before reinstalling.

- **Install the New or Cleaned MAF Sensor**:
- Position the new or cleaned sensor in place and secure it with bolts. Use the socket to tighten them snugly but don’t overtighten.

- **Reconnect the Wiring**:
- Push the wiring connector back into place until you hear a click.

- **Reattach the Air Intake Tube**:
- Place the tube back on the MAF sensor and throttle body, securing it with clamps.

- **Reconnect the Battery**:
- Reattach the negative terminal of the battery.

- **Testing**
- Start the engine and check for any warning lights on the dashboard. The engine should run smoothly if the MAF sensor was the issue.

- **Part Replacement**
- If the MAF sensor is dirty beyond cleaning, damaged, or if the engine continues to exhibit poor performance, a replacement MAF sensor will be necessary.
- Replacement part: Look for a compatible MAF sensor specifically for Jeep Wrangler TJ models, either OEM or a reputable aftermarket option.

- **Final Note**
- Always consult the vehicle’s service manual for specific details regarding your model and any additional steps that may be required.
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Tools & supplies
- Basic hand tools: ratchet, metric/deep socket set (including 10–22 mm), extensions, swivel
- Breaker bar, combination wrenches
- Torque wrench (capable to at least 150 ft·lb)
- Impact wrench (optional — use carefully)
- Transmission jack or heavy floor jack + wood block
- Engine support or hoist (to support engine if removing transmission)
- Jackstands and wheel chocks
- Drain pan, rags, shop light
- Pry bar and seal puller
- Flat and Phillips screwdrivers
- Line wrenches for cooler lines
- Thread locker (blue 242/243 or red 271 per factory spec)
- Replacement flexplate (correct part for your TJ year/engine/transmission)
- New flexplate and torque converter bolts (replace bolts if single‑use or corroded)
- New rear main/crankshaft seal (recommended while trans is out)
- Transmission fluid (and filter if applicable)
- Safety glasses and gloves

Safety first
- Work on a level surface. Chock front wheels. Disconnect battery negative.
- Raise vehicle on a lift or securely on jackstands rated for vehicle weight. Never rely on jack only.
- Support transmission with a transmission jack. Support engine with an engine hoist or support bar if removing bellhousing bolts—don’t let engine tilt.
- Wear eye protection and gloves. Have a floor pan for fluid and a clean area to lay parts.

Overview of procedure
You are removing the automatic transmission to replace/inspect the flexplate (flex plate). The critical items: fully seat the torque converter into the transmission before mating, use correct bolts and torque sequence, and torque to factory specs. Replace bolts if they are single‑use, rusted, stretched, or damaged. Also consider replacing rear main seal while tranny is out.

Step‑by‑step: removal
1. Prep
- Park, chock, disconnect battery.
- Raise and support vehicle safely. Remove skid plates if present.
2. Drain and remove driveshaft(s)
- Drain a small amount of transmission fluid to reduce mess (no need to fully drain if removing whole tranny).
- Remove rear driveshaft; support front if two shafts are present (depending on transfer case).
3. Support transmission and engine
- Place transmission jack under the transmission pan; take weight on jack.
- Support engine with hoist or support bar (so the engine won’t tip forward when bellhousing bolts are removed).
4. Remove external connections
- Remove starter and set aside.
- Disconnect electrical connectors at transmission (neutral safety, speedo, solenoids).
- Disconnect shifter linkage and transfer case linkage (or remove transfer case depending on method).
- Disconnect transmission cooler lines (catch fluid).
5. Remove bellhousing/transfer case bolts
- Remove bellhousing bolts that secure tranny to block. Keep track of bolt locations (lengths).
- If your TJ has a separate transfer case, unbolt it and slide it back far enough to access bellhousing bolts, or remove transfer case as required.
6. Separate transmission from engine
- Carefully slide transmission rearward on the jack. The torque converter must remain engaged with transmission input when you pull it off the engine enough that converter edge clears the flexplate. Slide until bellhousing clears the dowel pins.
- Lower transmission slightly and set aside so you can access flexplate.
7. Inspect torque converter engagement
- With tranny moved back, confirm torque converter is still attached or accessible. If already detached, mark converter position.

Step‑by‑step: flexplate removal
8. Access flexplate
- With transmission moved back, flexplate should be visible. Remove any dust shield.
9. Remove torque converter-to-flexplate bolts (if accessible)
- If torque converter bolts are installed and accessible, remove them now (support converter so it doesn’t rotate).
- If bolts were not accessible until transmission off, remove the flexplate bolts from the crank instead; whichever gives safest access.
10. Remove flexplate-to-crank bolts
- Remove all flexplate bolts. Keep bolts organized. Note: many manufacturers require new bolts; replace if single‑use or corroded.
11. Remove flexplate
- Slide the flexplate off the crank snout. Inspect ring gear teeth and crank pilot for damage. If ring gear is damaged, replace flexplate.

Inspection & prep before install
12. Inspect crank rear face, pilot, and seal area. Replace rear main/crankshaft seal now if leaking or as preventative maintenance.
13. Clean mating surface on crank. Chase threads in crank if corroded.
14. Compare old and new flexplate: bolt count, ring gear, hub thickness, tooth count — confirm exact match.

Installation of new flexplate
15. Position new flexplate onto crank pilot: align bolt holes and seat flush.
16. Apply thread locker per factory spec to flexplate-to-crank bolts (or dry if manual specifies). Start all bolts by hand to avoid cross‑threading.
17. Tighten bolts in a star/cross pattern in several increments to seat the flexplate evenly. DO NOT fully torque any single bolt first.
18. Final torque: use torque wrench and torque to factory spec. (Important: consult factory service manual for exact ft·lb for your year/model). If you don’t have the manual, do not overtighten — use measured incremental steps and check.
19. Inspect ring gear runout and flexplate seating. Spin by hand to check for wobble.

Reinstalling transmission & torque converter procedure (critical)
20. Ensure torque converter is properly installed on the transmission input shaft and seated into the pump prior to mating to the engine. How to confirm: push torque converter onto the input shaft until it drops in and fully seats — you should be able to see/feel it seated several millimeters further onto the input shaft; toggle until it engages with the pump (you will normally feel two distinct engagement points).
- Method A (preferred): With transmission out, install torque converter bolts onto flexplate loosely after seating converter, then mate tranny to engine and torque converter mounting bolts to spec.
- Method B: If you mate transmission to engine first, push transmission forward until converter fully engages the engine pump; then install and torque converter-to-flexplate bolts through access holes.
21. Carefully raise transmission with jack and guide it straight into bellhousing. Take care not to force linkage or damage the crank seal.
22. As you draw transmission forward, ensure dowel pins align and the transmission sits flush to the block. It often takes a few pushes to fully seat the torque converter into the pump — DO NOT bolt up bellhousing until converter is fully seated.
23. Once mate is complete, install torque converter-to-flexplate bolts. Use new bolts if specified and apply thread locker per spec. Tighten in a star pattern and torque to factory spec.
24. Reinstall bellhousing bolts, starter, cooler lines, wiring, linkage, and driveshaft. Refill transmission fluid and check level.
25. Lower vehicle, reconnect battery, start engine and check for unusual noises or leaks. Check starter engagement and that trans shifts through all gears. Road test and recheck bolts and fluid level.

How the tools are used (key points)
- Transmission jack: supports the weight and lets you control alignment when mating/transmission removal. Always use wood blocks to protect pan.
- Torque wrench: used for all critical bolts (flexplate-to-crank, torque converter-to-flexplate, bellhousing). Set to factory values and torque in sequence.
- Breaker bar: break loose stubborn bolts (avoid using impact to overtorque flexplate bolts).
- Pry bar: used to gently separate transmission from engine (between bellhousing and block), but don’t pry on flexplate teeth. Use pry on bellhousing lip.
- Thread locker: used per factory spec on torque converter and flexplate bolts to prevent loosening.

Common pitfalls & how to avoid them
- Not seating the torque converter fully into the transmission pump before mating — this can shear pump stator and cause immediate transmission failure. Always confirm full seating.
- Reusing old flexplate or torque converter bolts that are stretched/corroded — replace with new OEM bolts.
- Cross‑threading crank threads — start bolts by hand and use correct sockets.
- Over/under torqueing bolts — use torque wrench and factory specs.
- Damaging rear main seal when sliding transmission in/out — inspect/replace and use care.
- Not supporting engine — engine tilt can bend mounts or strain hoses.
- Using impact gun to tighten critical bolts — use torque wrench for final torque; impacts can overtorque.
- Forgetting to align starter and check for interference with flexplate teeth — ensure starter engages correctly.
- Not checking flexplate balance/runout — a warped or unbalanced flexplate causes vibration and drivetrain damage.

Replacement parts commonly required
- Flexplate (exact model for your TJ year, engine & trans)
- Flexplate bolts (often recommended to replace)
- Torque converter bolts (replace if single‑use or damaged)
- Rear main/crankshaft seal (highly recommended)
- Transmission fluid and filter (if applicable)
- Possible starter (inspect teeth and ring gear engagement)
- Thread locker (per spec)

Final notes
- Consult the Chrysler/Jeep factory service manual or a reliable repair manual for exact bolt torque values and bolt types for your specific year and transmission model. If you don’t have the manual, many repair databases and local dealers can provide torque specs.
- Take photos during disassembly to help during reassembly.
- If uncertain about torque converter seating or trans alignment, get assistance — improper installation can be catastrophic to a transmission.

That’s the full, technician‑level procedure. Follow factory torque specs and safety steps exactly.
rteeqp73

Quick overview (one-sentence): A synchronizer lets you smoothly engage gears by matching shaft speeds before the gear teeth lock together; repairing a worn synchronizer in a TJ means removing the transmission, disassembling the gear cluster, replacing worn synchronizer components (rings, keys, hubs or sleeves, and sometimes forks), measuring tolerances, and reassembling with correct clearances and fill. Below is a beginner‑level, thorough walkthrough: theory, parts, symptoms, tools, safety, step‑by‑step removal, bench teardown, inspection and measurements, replacement and reassembly, test and tips.

Theory — why synchronizers are needed and how they work (analogy)
- Purpose: A synchronizer (synchro) makes gear shifts smooth by bringing the rotating speed of a gear (on the output/layshaft) to the speed of the shaft that will drive it before the dog teeth engage. Without it you would have grinding, missed shifts, or need to double‑clutch.
- How it works (analogy): Imagine trying to fit two spinning bicycle pedals together. If one pedal spins faster, they clash. A synchronizer is like putting a rubber band around the faster pedal first to slow it down until both are same speed, then letting the pedal teeth mesh. The cone (friction) ring is the rubber band; the blocker ring is a gate that prevents the teeth from meshing until speeds match; the hub and sliding sleeve are the mechanism that slides to lock the gear once speeds are synced.
- Main actions:
- The shift fork moves the hub/sleeve toward a gear.
- The sleeve contacts the blocker ring, pressing the cones together and using friction to equalize speeds.
- Once speeds are matched the blocker ring aligns its notch with the hub dogs and the sleeve slides fully to engage the gear dogs.

Symptoms that tell you synchros need repair
- Grinding during shifts into a specific gear (often 2nd or 3rd).
- Difficulty getting into gear, especially when not rolling or when upshifting/downshifting at low RPM.
- Gear pops out or noisy engagement.
- If multiple gears are bad, possible oil contamination or general internal wear.

Which transmissions in a TJ?
- TJ Wranglers used various manuals (AX15 and later NV3550/NV3500 in different years). Core synchronizer design and repair ideas are similar across these 5‑speed boxes, but exact parts, snap rings, and torque specs differ. Always cross‑check the transmission model number on your case and consult the factory service manual for model‑specific details and torque values.

Major components of the synchronizer assembly (detailed)
- Hub: splined onto the layshaft; it is stationary relative to the shaft but allows the sleeve to slide.
- Sliding sleeve (selector sleeve): splines on the inside slide over the hub and have dog teeth that lock to gear dogs.
- Synchro (brass) ring / blocker ring / cone ring: friction cone (often brass or sintered material) that contacts the cone on the gear; has a notch that acts as a lock (blocks) until speeds match.
- Blocker ring spring / keys (sometimes spring‑loaded): ensure ring seats to cone and returns.
- Dog teeth on gear and sleeve: robust teeth that actually lock gear to hub once speeds match.
- Shift fork: pushes the sleeve via fork pad; may have a plastic/metal pad that contacts the sleeve.
- Shift rail/shaft and detent balls/springs: guide movement and provide tactile detent.
- Bearings (tapered/bushing) and races: support shafts and keep endplay correct.
- Layshaft (countershaft) & input/output shaft: where gears and hubs are mounted.
- Snap rings, spacers, thrust washers, seals: small parts that set clearances and oil sealing.

Tools and parts you’ll need
- Tools: socket set, breaker bar, torque wrench, screwdrivers, pry bars, snap‑ring pliers, drift punches, press (or large bench vise), gear puller, soft mallet, dial indicator with magnetic base, micrometer or calipers, pick set, solvent and brushes, shop press or bearing puller, clean trays for parts.
- Consumables and parts: new synchro ring(s), new hub/sleeve if damaged, new shift fork pads (if worn), bearing kits (if bearings show wear), seals and gaskets, new snap rings, shims (if required), proper gear oil (75W‑90 GL‑4 common), RTV gasket maker (if required), cleaning solvent, assembly lube.
- Safety gear: gloves, eye protection, jack stands, transmission jack.

Safety & prep
- Work on level ground, disconnect battery.
- Support vehicle with jack stands, or remove transmission on a lift.
- Label and photograph everything as you remove it (mark orientation of housings and shift rails).
- Cleanliness matters: small grit destroys synchro friction surfaces.

Vehicle removal (high level)
1. Drain transmission fluid.
2. Disconnect battery.
3. Remove driveshaft(s) from transmission (mark orientation), transfer case if 4WD is present — either drop transfer case or separate it from transmission depending on method.
4. Disconnect shift linkage, speedometer cable/sensor, starter, exhaust if needed, any wiring or ground straps attached.
5. Support transmission with a jack, remove crossmember(s) and mount bolts, unbolt bellhousing from engine block and slide transmission straight back off input shaft.
6. Lower transmission to bench. (Follow factory procedures for your model regarding transfer case separation.)

Bench disassembly — step‑by‑step (general)
Note: keep parts organized in order and orientation. Lay out in the direction of disassembly.
1. Remove tail housing: unbolt tail housing (shift lever area) and set aside.
2. Remove output shaft & gear(s): remove snap rings and pull output shaft assembly off.
3. Remove layshaft and its gears: pull the countershaft (layshaft) assembly.
4. Remove the hub/sleeve assemblies and synchronizer assemblies: usually held by snap rings and sometimes a small retainer or spring. Use snap‑ring pliers and a press if needed to separate hubs and sliding sleeves.
5. Remove bearings and races, noting orientation and any shims.
6. Remove shift forks and rails: mark which fork goes to which position and orientation. Check for fork pad wear.
7. Remove input shaft if required (it may be held by a nut/staked washer). Use correct procedures and be mindful of bearing preload arrangements.

Inspection and measuring (what to inspect and how)
- Synchro rings:
- Inspect cone surface for heavy grooves, glazing, heat discoloration, or missing friction material.
- Measure ring thickness and cone wear; compare to new parts. If cone face has deep grooves or a step that prevents consistent contact, replace.
- Blocker ring:
- Check notches and lining for wear; check spring/key function. If the notch or chamfer is worn beyond tolerance, it will allow early engagement and grinding.
- Hub and sleeve:
- Look for worn dog teeth, burrs, chipped or rounded dogs, scoring on sleeve splines.
- Sleeve bores may wear oval — check with calipers.
- Gear dogs:
- Inspect mating gear dog profiles; worn dogs will accelerate sleeve wear.
- Shift forks:
- Check for bent forks and wear at the pad. Replace or reline pads if worn.
- Bearings and races:
- Pitting, rough feel, or slop = replace.
- Shafts:
- Check splines for wear or galling. Damaged splines can cause poor clutching and premature syncho wear.
- Endplay and shaft runout:
- Measure input/output shaft endplay and lateral play with dial indicator and compare to specs; shim if necessary.

Common failure causes
- Worn brass cone rings from age or aggressive shifting (no clutch).
- Oil contamination (wrong oil — GL‑5 gear oil can be harmful to bronze synchros; use GL‑4 where recommended).
- Heat and glazing from slipping/clutch problems.
- Broken or weakened springs in blocker rings or connector keys.
- Worn shift fork pads or bent forks causing the sleeve not to slide squarely.
- Worn hub dogs or gear dogs, letting sleeve ride up and not fully engage.

Replacement decisions
- Replace cone (brass) rings whenever they are scored, glazed, or below manufacturer thickness.
- Replace hub/sleeve if dogs are rounded or the sleeve splines are worn so the sleeve binds or slides poorly.
- Replace shift fork pads or entire fork if bent.
- Replace bearings if rough or loose.
- Replace snap rings and seals.
- If multiple parts are worn, consider full synchronizer kit for that gear (many suppliers sell synchro kits with rings, springs/keys and sometimes hub/sleeve).

Reassembly (key steps and tips)
- Clean every part thoroughly with solvent and compressed air, dry and lightly oil bearings during initial assembly.
- Install bearings and races with correct orientation, using a press as needed.
- Install new synchro rings correctly oriented: the chamfered (tapered) face goes against the gear cone; notch orientation must match hub dogs; some rings are direction‑sensitive.
- Install blocker ring spring or keys correctly; make sure spring tension seats ring against cone.
- Reassemble hub and sleeve so sleeve slides freely but without excessive play.
- Install shift forks and rails in their original positions. Ensure fork pads sit squarely against sleeve.
- Reinstall layshaft and output shaft, with new snap rings and any required thrust washers/shims.
- Measure and set endplay/preload: use dial indicator and shims where required to achieve factory specifications.
- Torque bolts to factory specs — consult service manual for exact values, especially input shaft nut and bearing preload fasteners. Incorrect torque or preload will cause premature failure.
- Use new seals and gaskets; use assembly lube on friction surfaces lightly during assembly.

Refill and testing
- Reinstall transmission in vehicle in reverse of removal. Tighten bellhousing bolts in specified pattern and torque.
- Reconnect linkage, driveshafts, transfer case, speedo cable/sensor, starter, etc.
- Fill with correct gear oil (refer to OEM recommendation; many TJ manuals call for 75W‑90 GL‑4 or equivalent). Do not use extreme pressure GL‑5 if manual calls for GL‑4 or synchromesh oil.
- Start vehicle and test first in neutral for noise. Test drive carefully: shift through gears at low speed to verify smoothness before normal driving.
- Initial break‑in: avoid aggressive shifts and heavy loads for the first 100–300 miles.

Common mistakes and troubleshooting
- Not cleaning everything thoroughly — grit scars new parts.
- Reusing worn hub/sleeve while installing new rings — dogs must be in good shape.
- Incorrect ring orientation — results in no synchronization and grinding.
- Ignoring worn forks or pads — they control sleeve movement and alignment.
- Using wrong oil (GL‑5 in some manual transmissions) — GL‑5 can damage yellow metal (bronze/brass) synchros.
- Not setting bearing preload or shaft endplay correctly — causes noise, premature wear and bearing failure.
- Forgetting to replace small parts (snap rings, seals): they’re cheap insurance.

Notes specific to TJ transmissions
- Identify your tranny model (tag on case) and get the proper parts/synchro kits.
- AX15 and NV-series share the same synchronizer theory but have different internal arrangement and parts. Use the correct rebuild manual for layout, snap ring locations and torque specs.
- Speedometer drive and transfer case attachment points must be handled carefully — misalignment causes leaks and vibration.

Final checks and maintenance
- After 50–100 miles recheck fluid level and inspect for leaks.
- Recheck shift feel and re‑torque easily accessible fasteners after a short test drive.
- Maintain proper clutch adjustment and operation to avoid future synchro abuse.

Quick troubleshooting pointers (if problems persist after rebuild)
- Still grinding only under deceleration: suspect blocker ring seating or ring orientation.
- Grinding upshifts at higher RPMs: driver habit or clutch slipping/clutch drag.
- Gear jumps out: check dog teeth engagement, sleeve wear, or incorrect hub installation.

Summary (in one paragraph)
A synchronizer repair on a TJ is a bench reconstruction job: remove the transmission, disassemble the gear cluster, inspect and replace worn blocker/cone rings, hubs, sleeves, forks and bearings, measure and set endplay/preload, reassemble with correct parts and oil, and then reinstall and test. Focus on cleanliness, correct ring orientation, good dog teeth condition, correct bearing preload and using the proper manual transmission fluid — those are the critical factors that determine a successful synchronized gearbox repair.

You should consult the factory service manual for your exact TJ transmission model for the exact disassembly order, torque values, shim sizes, and endplay specs before starting.
rteeqp73