Pontiac FIREBIRD 1972 Service Manual page 1109

TURBO HYDRA-MATIC (M-38) TRANSMISSION
7G-7 1
ENDS TO B E SQUARE
WITHIN
'k4"
'm
SCRIBED LINE
= I
I ' % r " TO %"
% ' '
,
ROUND OR
FLAT STOCK
Fig. 7G-138 Comparison Gauge
NOTE: Gasoline or water vapor may settle in
vacuum side of diaphram. If this is found with-
out presence of transmission fluid, modulator
should not be replaced.
5. Bellows comparison check
-
a. Install known good modulator on either end of a
comparison gage (Fig. 76-138) and install
modulator in question on opposite end.
b. Holding modulator in horizontal position, bring
them together under pressure until either
modulator sleeve just touches line in center of
gage (Fig. 76-139).
c. Gap between opposite modulator sleeve ends and
center line of gage should be 1/16" or less (Fig.
7G- 140). If gap is greater than 1/16", modulator
in question should be replaced (Fig. 7G-141).
6. Inspect modulator valve for nicks or damage.
7. Check freeness of valve operation in case bore.
8. If modulator assembly passes all of above checks, it
is an acceptable part and should be re-used.
r
I
MODULATOR PART NUMBER
IS LOCATED ON BACK SIDE
HOLD MODULATORS IN A HORIZONTAL POSITION,AS SHOWN,
BRING THEM SLOWLY TOGETHER UNDER PRESSURE
Fig. 7G-139 Bringing Modulators Together
MODULATOR BELLOWS G O O D
Fig. 7G-140 Modulator Bellows Good
MODULATOR
IN QUESTION
KNOWN GOOD
MODULATOR
dg
MODULATOR BELLOWS BAD
~ J L -
- - --
Fig. 7G-14 1 Modulator Bellows Bad
M A N U A L A N D PARKING LINKAGE
INSPECT
1. Inspect manual shaft for damaged threads, rough oil
seal surface or looseness of shaft on range selector
inner lever.
2. Inspect range selector inner lever for cracks, loose-
ness on manual shaft or other damage.
3. Inspect detent roller and spring assembly for damage.
4. Inspect parking pawl actuating rod for cracks or
broken retainer lugs.
5. Inspect actuator for free fit on parking actuator rod.
6. Inspect parking pawl disengaging spring for de-
formed coils or ends.
7. Inspect parking lock bracket for cracks or wear.
8. If removed, inspect parking pawl and parking pawl
shaft for cracks, wear or other damage.