Pontiac FIREBIRD 1972 Service Manual page 842

THREE SPEED MUNCIE TRANSMISSION 7B-3
to jump-out for a long period, the cause must be
corrected plus replacement generally of the af-
fected gears.
d. Excessive end play in main drive gear, mainshaft
or counter gear caused by worn bearings, retain-
ers, etc.
e. Thrust washer or faces worn excessively, missing,
etc.
HARD SHIFTING
1.
Low level or wrong lubricant, especially if extreme
pressure-type lubricants are added.
2. Incorrect clutch linkage adjustment.
3. Improper adjustment of shift linkage, excessively
worn or damaged.
4. Shifter assembly mounting bolts too tight.
5. Worn, sprung shifter forks or worn shifter shafts.
6. Damaged synchronizer assemblies.
7. Burred or misaligned mainshaft.
STICKING IN GEAR
1. Wrong or low level of lubricant.
2. Clutch not releasing fully.
3. Worn chamfer on detent cam notches.
4. Damaged blocker ring or teeth of synchronizer
sleeve.
driver technique. Failure to control engine speed
drop-off during upshift, or failure to bring engine
speed nearly up to output shaft speed when down-
shifting, causes overwork of synchronizer and
failure to shift. Also, shifting without using clutch
will burn or wear out synchronizer at relatively
low mileage.
2. When shift lever moves directly into gear position
without resistance, raking of gears will be audible and
felt through the gearshift lever. This condition does
not always mean that synchronizer is worn out or
broken. The following may cause this condition:
a. Often, small chips may lodge temporarily in a
synchronizer which would prevent proper syn-
chronization and cause a raking shift. Continued
operation may either embed the chip below the
surface of the bronze blocker ring or reject it and
the synchronizer will return to normal function-
ing.
b. Use of improper lubricants often causes raking of
synchronizers. Heavy oil prevents synchronizer
from breaking through oil film and doing the job
properly. This raking noise usually occurs with
cold and heavy oil, but synchronizer begins to
function properly when normal operating tem-
perature of transmission oil is reached.
C AUTI 0
N
:
Use of extreme pressure-type lubri-
cants is not recommended. Glazing of synchro-
nizer blocker ring, due to breakdown of oil, is
especially common because of additives found
in extreme pressure lubricants.
ROUGH NEUTRAL CROSS-OVER
1. Improper adjustment of shift linkage.
2. Bent or damaged shift control rod (1st & Rev. or 2nd
& 3rd rod).
5. Misaligned mainshaft and/or countershaft.
LOCKS I N T W O GEARS AT SAME TIME
CLASHING OR RAKING OF GEARS
1. Raking of gears during shift duration is usually
caused by a defective synchronizer or improper shift-
ing technique:
1. Improper adjustment of shift linkage.
2. Bent or damaged shift control rod (1st & Rev. or 2nd
'
& 3rd rod).
a. Broken synchronizer components will sometimes
prevent proper movement of synchronizer sleeve,
resulting in clashing shifts.
OIL LEAKS
b. Worn synchronizer components, with loss of
clutching action, are usually caused by poor 1. Wrong lubricant or level too high.