Chevrolet 70 Series 1970, Service Manual

Page: 633 / 841

TRANSMISSIONS AND CLUTCHES 7-34
LOW RANGE
AIR PORT
HIGH RANGE,
AIR PORT
COVER
PISTON A
Figure 15—Range Shift Cylinder Seal Location
5. In sta ll the attaching p arts retaining the
diaphragm to the piston p late. Insert piston plate
and diaphragm a sse m b ly into the regulator body.
6
. Mount the body and end cap a sse m b lie s in
a v is e . Tighten lo ck ring firm ly .
Installation (R efer to F ig.
8
)
1. Attach regulator valve to the nipple p ro ­
truding from air f ilte r .
2. Tighten the la r g e hexagonal nut retaining
th e regulator v a lv e to the support b racket (not
show n).
3. Connect an a ir p r e s s u r e gauge to the outlet
port of the regulator v a lv e. Remount regulator and
a ir filte r bracket on the tra n sm issio n c a se .
4. R econnect a ir lin e s to the a ir filte r and
regulator valve.
5. P r e s s u r iz e the a ir sy ste m , then check for
lea k s (co rrect a s n e c e ssa r y ).
NOTE: Check the reading on the a ir p r e ssu r e
gauge which should be 57.5 to 62.5 p s i.I f the read­
ing does not correspond to this figu re, add or r e ­
m ove sh im s to the regulator a s d escrib ed p r e v i­
ou sly under "Regulator V alve A ssem b ly."
6
. R em ove p r e s s u r e gauge and reconnect air
lin e to outlet port of regulator valve.
RANGE SHIFT CYLINDER SEAL
REPLACEMENT (R efer to F ig. 15)
1. R em ove a ir lin e s from shift cylin d er.
NOTE: B e su re to p la c e p ro tectiv e caps over
the ends of the a ir lin e s to prevent entry of dirt
or other foreign m aterial into the a ir sy ste m .
2. R em ove co v e r from sh ift cylinder.
3. R em ove e la stic stop nut retaining piston to
sh ift bar.
4. Apply LIGHT amount of a ir p r e ssu r e at
low range a ir port to rem ove piston .
CAUTION: When using a ir pressure
to remove piston, do not stand in front of
range shift cylinder during removal.
5. R em ove s e a ls ("A” and "B”) from piston
and rep la c e with new s e a ls .
NOTE: Seal "C" is to be rep laced at tr a n s­
m issio n overhaul.
6
. Make su re shift cylinder b ore is clean.
In sert p iston into cylinder b ore with flat sid e of
p iston facing out.
7. In stall e la stic stop nut on shift bar. Tight­
en nut to 80-90 foot-pounds torque.
8
. In stall cover and gask et on the range shift
cylin d er. U se gasket cem ent SPARINGLY when
mounting gasket on the shift cylin d er. Tighten cap
sc r e w s to 35-45 foot-pounds torque.
NOTE: C over is in sta lled with high range air
port facin g upper left portion of range shift cylin d er.
9. Connect a ir lin e s to sh ift cylinder and
check fo r air lea k s.
SPLITTER CONTROL VALVE
(R efer to F ig. 16)
Porting
T here a re four p o rts in bottom of the control:
1. The port stam ped "S" is the supply port
and is the constant a ir lin e from the c r o s s on
range a ir valve.
2. The port stam ped "D" is the d eliv ery port
and i s connected to the shift cylinder cover center
port.
3. The port stam ped "E" is the exhaust port
and is left open.
4. The unm arked port is a blind port and not
u sed .
F ittin gs
A ll sp litter control a ir lin e s a r e 1/8" O .D .,
0.178" I.D . nylon tubing. The two con n ectors are
1/16" pipe thread; they a re not interchangeable
w ith the range sh ift control fittin g s w hich a r e
1
/
8
"
pipe thread.
Operation
The sp litter control valve is an "OFF-ON"
a ir sw itch .
1. With le v e r in "DIRECT" the v a lv e is clo sed .
A ir in the lin e to the sp litte r sh ift cylin d er cover
exhausts through the control valve when le v e r is
m oved from "OVERDRIVE” to "DIRECT."
2. With the le v e r in "OVERDRIVE" the con­
tr o l valve is open and air p a s s e s through to the
shift cylinder cover.
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL