Fifth gear lubrication starvation and gear stripping
SeriousGearbox & TransmissionOn five-speed manual Talbot Express gearboxes, fifth gear was incorporated within an auxiliary end-casing located high above the main sump oil level. When gearbox fluid drops slightly through weeping drive seals or neglected maintenance, fifth gear experiences severe lubrication starvation. Sustained motorway driving under the heavy load of a coachbuilt motorhome causes the gear teeth to overheat, whine, and eventually strip completely, leaving the driver unable to engage top gear or causing catastrophic gear lockup.
Distinct high-pitched whine under acceleration in fifth gear, Gear lever jumping violently out of fifth gear into neutral on motorway inclines
- Pull the gearbox oil dipstick on top of the casing to confirm oil is topped up to the maximum mark
- Conduct a test drive at 50 to 60 mph in fifth gear to verify quiet operation and positive engagement under load