Engines get the spotlight, but your gearbox, differential and retarder carry the load every day. When they’re neglected, heat, metal debris and misalignment quietly add up to catastrophic failures, and long, expensive lay‑ups. Here’s how to spot trouble early, what professional repairs involve, and how AMCS keeps your trucks earning.
Gearboxes: Manual, AMT and Automatic
Early Symptoms
- Gear clash, stiff shifts, flaring between gears (auto/AMT)
- Whine in specific ratios; delayed engagement; overheating on grades
- Metallic shavings on magnet plugs; burnt oil smell
Root Causes
- Incorrect or degraded oil; contamination after water crossings
- Clutch wear or poor calibration forcing abusive shifts
- Synchroniser, bearing or selector fork wear; mechatronic faults (AMT)
Professional Repair Path
- Oil analysis & endoscopic inspection to confirm wear patterns.
- Scan‑tool diagnostics and clutch calibration (AMT).
- Strip & assess: shafts, synchros, bearings, selectors, seals.
- Rebuild vs. replace decision driven by parts availability and turnaround.
- Bench run & road test with temperature, noise and shift‑quality validation.
Prevention Tips: stick to the correct OEM‑spec viscosity; keep breathers clear; calibrate clutches after replacements; avoid overloading and lugging which spike gearbox temps.
Differentials: Quiet Workhorses Under Constant Load
Red Flags
- Gear whine on cruise (pinion depth/backlash issues)
- Howl on coast, clunk on take‑off, or vibration under load
- Scorched oil, discoloured ring gear, excessive backlash
What Goes Wrong
- Incorrect setup after seal or bearing work
- Water ingress through breathers; blocked breathers raising internal pressure
- Diff‑lock abuse on high‑traction surfaces; over‑torque events
Repair & Setup Precision
- Pattern checks (blueing), backlash and pre‑load set with the right tools
- Replace bearings, crush sleeves and seals as a set
- Verify housing straightness and axle shaft run‑out before final torque
Pro Tip: pair diff and hub oil changes with magnet plug inspections; trend wear over time.
Retarders: Your Brakes’ Best Friend
Hydrodynamic or electromagnetic retarders dissipate kinetic energy without consuming brake linings, essential on long descents and heavy loads.
Typical faults: overheating from clogged coolers, low oil in gearbox‑mounted units, electrical supply issues on electromagnetic types, or control‑module errors.
Service essentials: cooler cleaning/pressure checks, oil and filter renewal where applicable, wiring/connector inspections, and functional testing on the road.
Putting It Together: A Preventative Driveline Plan
- Fluids first: correct spec, interval and sampling; trend iron/copper/lead in reports.
- Breather hygiene: keep diff and gearbox breathers clean and extended where needed.
- Alignment & mounts: engine/gearbox mounts and propshaft angles protect bearings.
- Driving discipline: avoid hopping curbs loaded; engage diff‑locks only on low‑traction surfaces; use retarders early on descents to manage heat.
- Seasonal checks: after water crossings or muddy seasons, inspect seals and oil condition.
How AMCS Reduces Driveline Downtime
- Complete capability across gearboxes, differentials, retarders, brakes and clutches, core services AMCS is known for. AMCS
- Rapid turnaround: rebuilds guided by parts availability; transparent strip‑and‑quote process.
- Field support: where practical, inspections and certain repairs performed onsite; 24/7 breakdown support in West Rand and surrounding areas keeps fleets moving. AMCS
- Proof of repair: oil temperature/noise trend logs from test drives; post‑repair service schedule and driver guidance.
When Should You Rebuild vs Replace?
- Rebuild when housings and gearsets are serviceable and parts are readily available.
- Replace when gears are spalled/chipped, housings are cracked/warped, or downtime costs outweigh rebuild savings.
Book a driveline assessment
If you’re hearing whines, feeling vibrations or seeing metal on plug magnets, don’t wait, book an AMCS driveline inspection and protect your fleet’s uptime.