GMC 1990 Light Truck Repair Manual page 280

4C3-12 T TRUCK FRONT AXLE
Carrier Case
29.
32. Sleeve
A. Mark Location on the Case
Figure 26—Marking Sleeve Location
10. Check and record the backlash at three or four
points around the ring gear.
• The pinion must be held stationary when
checking backlash.
• The backlash should be the same at each
point within 0.05 mm (0.002-inch). If the
backlash varies
(0.002-inch), check for burrs, a distorted case
flange, uneven bolting conditions, or foreign
matter between the case and the ring gear.
• G ear backlash
0.08-0.25 mm (0.003-0.010-inch) with a
preferred sp e cifica to n of 0.13-0.18 mm
(0.005-0.007-inch).
• If the backlash is incorrect, adjust the sleeves
as necessary. Always maintain the " one
n o tch " preload on the side bearings.
EXAMPLE: If it is necessary to turn the RIGHT
sleeve IN one notch, the LEFT sleeve must be
turned OUT one notch.
J 25025-1
Figure 27—Measuring Backlash at the Ring Gear
29
F-01830
more than 0.05 mm
should be between
J 34047
F-05881
Figure 28—Measuring Backlash at the
Pinion Flange
• To increase backlash, turn the left sleeve in,
and turn the right sleeve out an identical
amount. To decrease backlash, turn the right
sleeve in and turn the left sleeve out an
identical amount.
10. When the backlash is correct, mark the position of
the sleeves so they can be kept in the same
location.
MEASURING BACKLASH (ALTERNATE METHOD)
1. Use this method if the tools specified previously are
not available.
2. If the specified tools are not available, it is possible
to read backlash at the pinion flange as follows:
3. Install a dial indicator so the button contacts the
outer edge of the pinion flange. The plunger must
be at a right angle to the pinion flange (figure 28).
4. Move the pinion flange through its free play while
holding the differential carrier. Record the dial
indicator reading.
5. DIVIDE THE DIAL INDICATOR READING BY 2 to
obtain the actual backlash when using this method.
Example: A dial indicator reading of 0.16 mm means
that there is actually 0.08 mm backlash.
6. Follw the steps for adjusting backlash outlined
previously.
F-05875