Chevrolet DB90 Series, Service Manual

Page: 162 / 242

S ec. 7A -156
TRANSMISSON CONTROL LINKAGE
t
Figure 8 —TV Linkage (T M 8 0 )
shown in figure 5. Shorten or lengthen TV rod (I)
to obtain alignm ent with gauge by perform ing the
following:
a. Have a ssista n t loosen retaining nut (C)
holding slo tted -ro d (B) in position on TV rod (I).
b. R eferring to figure 5, align TV le v e r (G)
with "IDLE” line on gauge.
c. With a ccelera to r linkage at "IDLE” p o s i­
tion, have a ssista n t position slo tted -ro d (B) so
upper portion of slo t contacts stud (L). Secure
slo tted -ro d (B) to TV rod (I) by tightening nut (C).
R echeck TV lev er (G) on tra n sm issio n to be sure
it is aligned with "IDLE" line on gauge (fig. 5).
15. Have a ssista n t d ep ress a ccelera to r pedal
to full throttle (DETENT - just touching detent
button). R eferring to figure 6, TV lev er should be
aligned with "LONG STROKE" line on gauge.
NOTE: Any under- or o v er-tr a v el in Step 15
indicates faulty or im proper linkage com ponents.
16. Rem ove gauge from tra n sm issio n and con­
nect manual range se le c to r linkage at tra n sm issio n .
17. Check TV linkage by having a ssista n t de­
p r e s s a ccelera to r pedal to THRU-DETENT (detent
button - com p ressed ). Hold TV le v e r (G) in this
p osition . When a ssista n t r e le a s e s the a cce lera to r
pedal, carburetor throttle lev er (J) and a cce lera to r
pedal must return fr e e ly to "IDLE" p osition. Con­
nect TV le v e r return spring (H).
18. U sing a tachom eter to accu rately check
engine rpm, with s e le c to r lev er in "N" (neutral),
rech eck engine idle speed (525 rpm ). Road te st or
dynam om eter te s t veh icle to check for full load
upshift (5th to 6th). Upshift should occur at ap­
p roxim ately 50 rpm below the engine governed
sp eed (3400 rpm with 401M engine). If upshifts do
not occur at sp ecified rpm adjust a s follow s:
a. To r a is e shift point shorten TV rod (I) by
loosening nut (C), then reposition slo tted -ro d (B)
a s required. Tighten nut (C) against shoulder of
rod (I).
b. To low er shift point, lengthen rod (I) in the
sam e manner a s the preceding step.
TV Linkage Adjustm ent
- Model RM80
IMPORTANT: Be su re engine id le (575-600
rpm) and governed speed a re properly adjusted
before proceeding. R efer to ENGINE FUEL SYS­
TEM (SEC. 6M) of Heavy Duty Truck S ervice
Manual ST 135-70 and Supplement ST332-71 for
adjustm ents.
NOTE: Key le tte r s in text re fer to figu re 9.
1. Apply parking brake and block v e h ic le ’s
driving w h eels.
2. To fa c ilita te installation of TV Linkage Ad­
justm ent Gauge (J-23739) disconnect manual range
se le c to r linkage at tr a n sm issio n .
3. L oosen nut (E) on slo tted -ro d (J). D iscon ­
nect TV le v e r return spring (M) from TV le v e r (L).
4. Have a ssista n t d ep ress a ccelera to r pedal
(B) until contact is made with stop bolt (C) and hold
in this position . The carburetor throttle le v e r (G)
should be in fu ll throttle position . If adjustm ent is
n e c e ssa r y , lo o sen jam nuts (D) and rotate turn-
buckle (N) until a ccelera to r pedal (B) con tacts stop
bolt (C) with carburetor throttle le v e r in full throt­
tle position . Retighten jam nuts (D).
NOTE: Stop bolt (C) may be rep osition ed , if
su fficien t adjustm ent cannot be attained in Step 4.
5. In stall gauge (J-23739) as shown in figure
3. Note that gauge is in sta lled on manual se le c to r
nut.
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT