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Analysis Aid in the event of Complaints Concerning
Manual Transmission Noises (R25/R28/R30)
Noises from the drive train giving cause for complaints do not
necessarily come from the manual transmission. The following table
serves to reduce complaints concerning noises from R 25/28/30
manual transmissions.
Vehicle is Stationary with Engine Idling
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Complaint:
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Noise only occurs when clutch pedal is
depressed
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Type of noise
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Additional information
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Remedy
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Bearing noise
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Ensure complete and correct seating of both fit sleeves at
engine flange and lubrication of pilot bearing (guide bearing)
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Replace pilot gear, replace release bearing of central
release.
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Knocking noise
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Audible noises usually in the lower engine speed range
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Replace dual-mass flywheel; further trouble shooting in the
engine
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Complaint:
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Noise occurs both when clutch is depressed and not
depressed.
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Type of noise
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Additional information
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Remedy
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-
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Noise comes from engine area.
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Locate source of noise more precisely in engine.
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Complaint:
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Noise becomes louder when clutch pedal is
depressed
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Type of noise
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Additional information
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Remedy
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-
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Noise comes from engine area.
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Replace release bearing of central release
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Driven Vehicle
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Complaint:
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Noise only occurs when clutch pedal is
depressed
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Type of noise
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Additional information
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Remedy
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Whining, screaming
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Noise becomes louder when 1st/2nd / 3rd/5th or reverse gear is
engaged
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Replace 1st/2nd / 3rd/5th or reverse gear and layshaft
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Complaint:
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Noise only occurs when clutch pedal is
depressed
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Type of noise
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Additional information
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Remedy
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Noise depends on load condition Idle speed, full load/partial
load, traction/overrun, float
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Noise becomes quieter especially when 4th gear is engaged and is
audible when all other gears are engaged
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Replace drive shaft and layshaft
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Regular knocking
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especially in 3rd and 5th gear
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Noise becomes quieter when 4th gear is engaged
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Noise disappears when 4th gear is engaged
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Exchange roller bearing for main shaft in the drive shaft
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Noise only becomes quieter
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Replace drive shaft bearing and/or layshaft bearing
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Complaint:
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Noise only occurs when clutch pedal is
depressed
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Type of noise
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Additional information
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Remedy
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Noise becomes louder when reverse gear is engaged
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Noise is especially audible at fastening bolts of reverse idler
gear axle at transmission housing and extension
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Replace reverse idler gear bearing
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Noise disappears when forward gear is engaged
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Replace bearing of appropriate gear
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Locate source of noise more precisely – loose parts
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Scraping / rasping
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When stationary with clutch not depressed, synchronise gears
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Noise becomes quieter for synchronised gear
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Check synchronisation of each synchronised gear
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Complaint:
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Noise only occurs when clutch pedal is
depressed
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Type of noise
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Additional information
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Remedy
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Noise becomes louder with gears synchronised
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Check shift forks of each synchronised gear. Noise can also be
heard in other gear with the same shift pattern (1 – 2, 3-4,
5-R).
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Replace relevant shift fork / shift sleeve (sliding gear)
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Noise unchanged
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Check reference gap between clutch toothing and main shaft. Also
check reference gap for layshaft.
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Replace complete transmission
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Complaint:
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The source of the noise is not identifiable by the
trouble shooting measures described above
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Search for / locate noises in the axle bearings, wheel bearings
and axle shaft.
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