Worn spring pivot bearings
Loose frame or axle U-bolts
Engine cooling fan out of balance
Engine crankshaft, flywheel, and/or clutch
plate out of balance
Tires or wheels wobbly or mismatched
This list, along with other troubles you have
encountered in your own experience, can be used as a
step-by-step guide in transmission noise trouble-
shooting. Make sure that all possibility of outside noise
has been eliminated before you have your personnel
remove the transmission.
When analyzing a vehicle for transmission noise,
raise the vehicle so that the driving wheels are clear of
the deck. Start and operate the vehicle in all the speed
ranges, including COASTING with the shift lever in
neutral. Listen carefully for noises and try to determine
the origin. There are other procedures for checking
transmission noises that may be used. Principally, any
procedure used relies on the experience and good
judgment of the mechanic doing the troubleshooting.
When it is determined that the noise is with the
transmission, generally it is necessary for the transmis-
sion to be removed from the vehicle and disassembled.
Remember, however, you should never be satisfied
with just finding and correcting the trouble. You should
always try to find what caused the trouble. If you find a
transmission with broken gear teeth, do not be satisfied
with just replacing the transmission. Try to find out what
caused the transmission to malfunction.
Whenever you find such components as the
transmission in an unserviceable condition, talk to the
driver. The driver may be able to explain exactly how
the failure occurred and give you a clue as to the cause
of the failure.
If you fail to find the cause, you will probably have
to do the job over because the same trouble will most
likely develop in the replacement transmission.
Table 11-1 is a basic troubleshooting chart. As
Table 11-1.Troubleshooting Transmissions (5-ton military)