Chevrolet 70 Series 1970, Service Manual

Page: 645 / 841

TRANSMISSIONS AND CLUTCHES 7-46
Figure 70—Typical Clutch Hydraulic
System (TM 80 and TV 70)
1. Maintain proper le v e l of hydraulic fluid in
m a ster cy lin d er. R efer to LUBRICATION (SEC. 0)
in th is manual for recom m ended fluid and checking
in te r v a ls. At le a st once a y ea r, drain and flush the
en tire clutch s y s te m and r e fill with new fluid.
2. Inspect en tire clutch sy ste m regularly for
fluid leak age. Leakage m ust be co rre cte d im ­
m ediately.
3. Make su re return spring at sla v e cylinder
i s not weak or broken.
4 . Check and if n e c e ssa r y adjust clutch pedal
linkage. In stru ction s a re explained la ter under
"Clutch Control A djustm ents."
5. If clutch pedal action is springy o r spongy,
it i s an indication that a ir needs to be b led from
hydraulic sy ste m o r adjustm ent is n e c e ssa r y .
6. Clutch r e le a s e bearing, when equipped with
g r e a s e cup, m ust be lubricated at regular in terv a ls
a s d irected in LUBRICATION (SEC. 0) in th is manual
CLUTCH CONTROL ADJUSTMENTS
IMPORTANT: P r o ced u res fo r adjusting the
clutch co n tro ls on HN, JN90 when equipped with
a S p icer clutch a r e found la ter in th is se c tio n .
A djustm ents a r e g en erally required due to
w ear of p a r ts, or w henever the m a ster cylin d er,
sla v e cylin d er, o r clutch a ssem b ly has been r e ­
p laced.
To obtain proper clutch operation, two adjust­
m ents a re required: M aster cylinder push rod ad­
justm ent and the sla v e cylin d er push rod adjustm ent.
NOTE: M aster cylin d er push rod adjustm ent
is not required on s te e l tilt cab m od els, except
TM80 and TV70.
P u rp ose of m a ster cylinder push rod adjust­
ment is to ensure fu ll return of m a ster cylinder
Figure 11 —Clufch Hydraulic System ISteel Tilt
Cab Models Except TM 80 and TV 70)
p isto n when foot is rem oved from p ed al. If push
rod i s adjusted too long, p iston could r e s tr ic t the
b yp ass port in cylin d er, and clutch would not en­
gage fu lly , thereby causing clutch to s lip . Too short
a push rod would re su lt in e x c e s s iv e pedal fr e e -
tr a v el b efore clutch s ta r ts to d isen gage.
P u rp ose of sla v e cylinder push rod adjustm ent
i s to provide p rop er p osition of clutch r e le a s e
bearing when the clutch is engaged.
P r io r to making adjustm ents the hydraulic
s y s te m m ust be fr e e of air and the m a ster cylinder
m ust be fille d to J^-inch below fille r opening.
IMPORTANT: If clutch control adjustm ents
a r e to be made, ALWAYS make adjustm ent at the
m a ster cylinder b efore making adjustm ent at the
s la v e cylin d er.
A c c e s s to the m a ster cylinder on s te e l tilt cab
m odels TM80 and TV70 is gained after r e ­
moving sm a ll a c c e s s door located at front of
d r iv e r ’s sea t r is e r a s shown in figu re 13. This
m a ster cylinder is bracket-m ounted below the cab
floorin g a s shown in figu re 10. A c c e s s to pedal
linkage for checking and adjusting p u rp oses is
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL