Chevrolet 70 1969 Series, Shop Manual

Page: 892 / 913

STEERING 9-16
Figure 12— Installing Control Valve (Teflon) Rings
replaced. As on the spool a slight polishing is norm al
on the valving surfaces.
8. Check fit of the spool in the valve body bore without
the valve spool dam pener O-ring seal (14) are lubri­
cant. The spool should rotate sm oothly w ithout bind­
ing or catching. If either occurs, the entire valve as­
sembly should be replaced. A small burr on the spool
or in the valve body can usually be removed with very
fine hone.
9. Check valve spool spring (13) for free length, com ­
pressed length, distortion, or collapsed coils. Free
length of spring should be 0.82 inch. If it measures
0.79 inch or less, the spring should be replaced.
ASSEMBLY
1. Lubricate four new valve body (Teflon) rings (16) and
four new back-up seals (17) in “ Type A ” hydraulic
fluid. Assemble rings and seals in four ring grooves
F ig u re 1 3 — In s ta llin g V a lv e S p o o l S p rin g
on the valve body. S tart at end of valve and w ork to
opposite end as shown in figure 12.
NOTE: Do not allow the seals to become twist­
ed. Assemble rings in grooves over the O-ring
seals by carefully slipping rings over the valve
body. The rings may appear loose or twisted in
the grooves but heat of the oil during operation
after assembly will cause them to straighten.
2. Install a new valve spool dam pener O-ring seal (14) in
valve spool groove. Lubricate the seal in “ Type A "
hydraulic fluid. Do not allow seal to twist in ring
groove.
3. Assem ble stub shaft (20) in valve body (18), aligning
groove in valve cap with pin in valve body. T ap lightly
on cap with a plastic ham m er, until cap is against
shoulder in valve body with valve body pin in cap
groove.
IMPORTANT: Make sure the groove and pin
are in line before tapping on cap. Hold these
parts together during balance of the assembly
procedures.
4. Lubricate valve spool (15) with “ Type A ” hydraulic
fluid. Slide spool over stub shaft (20) with notch tow ­
ard valve body. Align notch with the spool drive pin
in stub shaft and carefully engage spool in valve body
bore.
IMPORTANT: Because the clearance between
the spool and valve body is very small, extreme
care must be taken when assembling these
parts. Push the spool evenly and slowly with a
slight oscillating motion until the spool reaches
the drive pin. Rotate the spool slowly until the
notch engages the pin. Before pushing the
spool completely in, make sure the valve spool
dampener O-ring seal is evenly distributed in
the spool groove. Slowly push the spool com­
pletely in, using extreme care not to cut or
pinch the O-ring seal.
5. Position seal protector (J-6222) over stub shaft. Slide
the valve spool spring (13) over the seal protector and
w ork spool spring down until it is seated in the under­
cut part of stub shaft (fig. 13). T ake care not to
scratch or m ar the sealing surfaces of stub shaft.
6. If during assem bly of the valve, the stub shaft and cap
assembly is allowed to slip out of engagem ent with
the valve body pin, the spool will be perm itted to
enter the valve body too far. T he dam pener O-ring
seal (14) will expand into the valve body oil grooves
preventing withdrawal of the spool. A ttem p t to w ith­
draw spool with slight pull and m uch rotary motion.
If this does not free the spool after several tries, m ake
sure spool is free to rotate; then place valve body on a
flat surface with notched end up and tap spool with
wooden or plastic rod until the O-ring seal is cut and
the spool can be removed. R eplace dam pener O-ring
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L