GMC 4000 Series Service Manual page 462

Figure 9 — Master Cylinder Push Rod
Check and Adjustment ("L" Models)
door located at front of driver's seat riser as
shown in figure 7.
Master cylinder on " L" models is bracket-
mounted below cab flooring as shown in figure 8.
A ccess to pedal linkage for checking and adjusting
purposes is made when cab is tilted completely
forward. However, when checking and replenish­
ing fluid in master cylinder, the cab must be in
its lowered or operating position.
After servicing fluid system on " V* models,
examine door opening or cover seal. Apply new
caulking if necessary before installing door,
otherwise dust may enter cab later at this point.
MASTER CYLINDER PUSH ROD
CHECK A N D ADJUSTMENT
Before making adjustment, pull the master
cylinder boot back on push rod. Visually check
to see if the piston is seated firm ly against piston
snap ring in cylinder bore (fig. 9). If not, the push
rod is too long and should be shortened, as di­
rected later.
IMPORTANT: It is better to have push rod
adjusted too short than for it to be too long. If
the push rod is too long the clutch will not fully
engage.
Loosen lock nut on master cylinder push rod
assembly, then turn hex portion of push rod (fig.
10) as necessary to provide 0 to l/l6 -in c h clear­
ance between push rod and master cylinder piston.
After making adjustment, tighten lock nut on push
rod. Make sure piston contacts snap ring in mas­
ter cylinder bore when pedal is released. Install
boot on master cylinder.
G M C S E R V I C E M A N U A L
CLUTCH CONTROLS
Figure 10— Adjusting Master Cylinder Push Rod
Figure 11 — Improvised Tool Dim ensions
(for Checking 'A-Inch Clearance)
Sec. 7D
Page 451