Chevrolet 10 Series 1970, Service Manual

Page: 461 / 671

CLUTCHES AND TRANSMISSIONS 7-31
ALUMINUM POWERGLIDE
INDEX
Page
General D e s c rip tio n .............................................................................. 7-31
Maintenance and A d ju s tm e n ts ............................................................ 7-31
O il L evel Check ................................................................................ 7-31
Periodic O il Change ......................................................................... 7-31
Periodic L o w Band A d ju s t m e n t ..................................................... 7-32
Manual Shift Linkage Check and A d j u s t .................................... 7-32
T h ro ttle V alve L i n k a g e ................................................................ 7-33
Neutral Safety S w i t c h ................................................................... 7-33
T h ro ttle Return Check Valve (D a s h p o t ) .................................... 7-33
Com ponent Parts R e p la c e m e n t.......................................................... 7-34
Transmission R e p la c e m e n t.............................................................. 7-34
Other Service O p e ra tio n s..................................................................... 7-34
Diagnosis ........................................................................................... 7-35
Warming Up T ra n sm ission ........ ................................................................
7-35
Shop Warm U p .................................................................................. ......
7.35
Road Warm U p .................................................................................. ......
7.35
Checking Fluid Level and C o n d it io n .......................................................
7.35
Manual L in k a g e .................................................................................... ......
7.35
O il L e a k s ............................................................................................... ......
7.36
Basic Pressure Checks ......................................................................... ......
7.36
Wide O pen T h ro ttle U pshift Pressure C h e c k ................................. ......
7.35
Idle Pressure in Drive R a n g e ............. .............................. ............... ......
7.36
Manual “ L o w ” Range Pressure Check .......................................... ......
7.36
D rive Range Overrun (C oa st) Pressure .......................................... ......
7.35
Pow erglide Shift P o i n t s ....................................................................... ......
7.37
GENERAL DESCRIPTION
The case and co n v e rte r housing of the two speed alum i­
num P o w e rg lid e T ra n sm ission is a sin gle case aluminum
unit. When the manual con trol is placed in the d rive po­
sition, the tran sm ission autom atically shifts to low gea r
fo r in itia l v e h icle m ovem ent. A s the truck gains speed
and depending on load and th rottle position, an automatic
sh ift is made to high gea r. A fo r c e d downshift feature
p ro vid es a passing g e a r by returning the tran sm ission to
low range.
The o il pump assem bly is a conventional gea r type and
the o il pump housing is of the la rg e diam eter type acting
as the fron t bulkhead o f the tran sm ission . The torque
c o n v e rte r is a conventional th ree elem ent w elded design
b olted to the engine fly w h eel which d riv e s through a two-
speed planetary gea rset. The high clutch assem bly is
typ ical of the designs used in this type transm ission. The
aluminum P o w e rg lid e uses an output shaft mounted gov­
ern o r which req u ires a hole through the output shaft.
The r e v e r s e clutch a ssem b ly is a m ultiple disc type
clutch. The ste e l p lates a re splined d ir e c tly to the case
w hile the fa c e plates a re splined to the in tern al o r rin g
gea r. The clutch piston operates within the r e a r portion
of the case. The intern al diam eter of the piston is sealed
to an in tegra l hub portion of the case re a r bulkhead. The
outside d ia m eter is sealed to a machined portion o f the
case. The piston is h ydrau lically applied and is re le a s e d
by separate c o il sprin gs. The v a lv e body assem bly is
b olted to the bottom o f the tran sm ission case and is ac­
ce s s ib le fo r s e r v ic e by rem ovin g the o il pan assem bly.
The va lve body consists o f an upper and lo w e r body lo ­
cated on eith er side of a tra n sfer plate. The vacuum
m odulator is located on the le ft r e a r fa ce of the tran s­
m ission case. The m odulator va lve b o re is located in the
upper v a lv e body.
MAINTENANCE AND ADJUSTMENTS
OIL LEVEL CHECK
The tran sm ission o il le v e l should be checked p e rio d i­
ca lly as recom m ended in Section 0. O il should be added
only when le v e l is on o r below the “ ADD” m ark on the
dip stick with o il hot o r at operating tem peratu re. The o il
le v e l dip stick is located at the righ t r e a r o f the engine
com partm ent. F ill with o il s p e c ifie d in Section 0.
In o rd e r to check o il le v e l accu rately, the engine should
be id led with the tran sm ission o il hot and the con trol
le v e r in neutral (N ) position.
It is im portant that the le v e l be maintained no higher
than the “ F U L L ” m ark on the tran sm ission o il le v e l
gauge. DO N O T O V E R F IL L , fo r when the o il le v e l is
at the fu ll m ark on the dip stick, it is just slig h tly be­
low the plan etary gea r unit. If additional o il is added,
b rin gin g the o il le v e l above the fu ll m ark, the planetary
unit w ill run in the oil, foam ing and aeratin g the oil. This
aera ted o il c a r r ie d through the variou s o il p ressu re pas­
sages (low s e rv o , r e v e r s e s ervo , clutch apply, co n verter,
e tc .) may cause malfunction o f the tran sm ission a ssem ­
bly, resu ltin g in cavitation noise in the co n verter and
im p ro p er band o r clutch application. O verheating may
also occur.
I f the tran sm ission is found consistently low on oil, a
thorough inspection should be made to find and c o r r e c t a ll
extern a l o il leaks.
PERIODIC OIL C H A N G E
The tran sm ission o il should be changed p e rio d ic a lly as
recom m ended in Section 0, and whenever tran sm ission is
to be rem oved fro m the ve h ic le fo r rep a irs.
1. Run engine fo r one minute in neutral p r io r to
changing.
2. Be sure v e h ic le is le v e l o r ra is e fro m the re a r only.
3. Rem ove the o il pan drain plug and allow o il to drain
thoroughly into a pan o r can.
4. R eplace drain plug and r e f ill with approxim ately two
quarts of o il s p e c ifie d in Section 0.
NOTE: T o r e f i l l the transm ission, rem ove dip
stick fro m o il f i l l e r tube and r e f ill tran sm ission
with o il s p e c ifie d in Section 0. Then, a f t e r
shifting into a ll ranges at id le speed to f i l l a ll
o il passages, the engine should be run at 800-
1000 rpm with the tran sm ission in N eu tral until
the o il w arm s up, then add o il as requ ired to
ra is e the flu id le v e l to the fu ll m ark on the dip
stick. R e fill capacity is approxim ately 2 qts.
(U.S. m easure 1-3/4 qts. Im p eria l m easu re).
CHEVROLET TRUCK SERVICE MANUAL