Help with fault analysis in the event of claims concerning noise from a manual gearbox
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Help with fault analysis in the event of claims concerning noise from a manual gearbox
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Transmission noise may not always come from the manual gearbox. The following table should be used to reduce noise relating to the F 17 manual gearbox.
1. The car is stationary and the engine is idling
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The noise only arises when the clutch pedal is depressed:
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Type of noise
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Extra information
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Action
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Bearing noise
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Vibrating clutch pedal
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Check the clutch plate.
Check the position of the clutch delivery line.
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Knocking noise
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Audible sound, usually at lower engine speeds.
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Further fault diagnosis on the engine
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The noise arises irrespective of clutch pedal position:
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Type of noise
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Extra information
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Action
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-
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Vibrating clutch pedal
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Localise the noise source on the engine
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The noise increases when the clutch pedal is depressed:
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Type of noise
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Extra information
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Action
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-
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The noise comes from the engine
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Check the central clutch release bearing
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Rattling
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With gear engaged
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Check the synchromesh of the gear
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2. The car is being driven
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The noise occurs only with depressed clutch pedal:
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Type of noise
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Extra information
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Action
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Howling, whining
The noise depends on the loading condition in all gears:
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The noise increases with the 1st, 2nd, 3rd, 4th or reverse gears engaged and with higher speed
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Change the pinion of the respective gear and the gear wheel block
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The noise increases predominantly in 4th gear and is audible in all the other gears
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Check the differential gears, replace if necessary
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Rattling
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Audible with change from 2-1
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Check the synchromesh of the 5th gear
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Audible with acceleration from low engine speed and in each gear engaged
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Check the tooth flank clearance on the wheel pair for the gear in question and replace if necessary
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Scraping/slipping sound
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When stationary and without depressed clutch pedal, gears not synchronous
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The sound reduces when the gears are asynchronised
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Check the synchromesh on every asynchronised gear
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The sound increases when the gears are asynchronised
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Check the selector forks on each asynchronised gear and the track in the synchromesh hub or sleeve
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Replace the pertinent selector fork/ synchromesh sleeve or hub
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Sound unchanged
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Check the play between the clutch gears and the baulk rings
Check the tooth flank backlash between the gear wheel block and the pinion
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Change the complete bearing housing
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The source of the noise cannot be detected using the fault diagnosis described above: Investigate and locate the noise at shaft bearings, wheel bearings and drive shafts
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