chevrolet truck Light Duty Truck 1994 Series Repair Manual Download

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4. Place the indicator stem at the heel end of a tooth.

• Set the dial indicator so the stem is in line with

the gear rotation and perpendicular to the tooth

angle (figure 25).

NOTICE: Refer to "Notice" on page 4B2-1.

5. Install the differential caps and bolts.

Tighten

• The bolts to 80 N-m (60 lbs. ft.).

6. Check and record the backlash at three or four

points around the ring gear.

• The pinion must be held stationary when check

ing backlash.

• The backlash should be the same at each point

within  0.05  mm  (0.002  inch).  If  the  backlash
varies  more  than  0.05  mm  (0.002  inch),  check
for  burrs,  a  distorted  case  flange,  uneven  bolt

ing conditions, or foreign matter between the
case and ring gear.

7. Backlash at the minimum lash point measured

should be between 0.13 to 0.23 mm (0.005 to
0.009 inch) for all new gear sets.

8. If the backlash is not within specifications, move

the  ring  gear  in  or  out from  the  pinion  by  increasing
the  thickness  of  one  shim,  and  decreasing  the
thickness  of  the  other  shim  the  same  amount.  This
will  maintain  the  correct  axle  side  bearing  preload.

• Moving 0.003 inch worth of shim from one side

of the differential to the other will change the

backlash adjustment by 0.002 inch.

9. Recheck the backlash and correct as necessary.

GEAR TO OTH

PATTERN CHECK

Checking the ring gear to pinion tooth pattern is to be

done only after setting up the axle according to the

methods in this section. The pattern check is NEVER to

be used as an initial check, or instead of checking pin
ion depth and backlash adjustments. This check is only

to be used to verify the correct adjustment of the gear
set after setup.

1. Wipe all oil out of the case and carefully clean

each tooth of the ring gear (figure 26).

2. Apply gear marking compound (GM P/N 1052351)

or equivalent sparingly to  all  ring  gear teeth  using  a
medium-stiff  brush.  When  properly  used,  the  area
of  pinion  tooth  contact  will  be  visible  when  hand
load  is  applied.

3. Tighten the bearing cap bolts to the specified

torque.

4. Expand the brake shoes until a torque of 40 to 50

lbs. ft. is required to turn the pinion.

Important

• A test made without loading the gears will not

give  a  satisfactory  pattern.  Turn  the  pinion
flange  with  a  wrench  so  the  ring  gear  rotates
one  full  revolution,  then  reverse  the  rotation  so
the  ring  gear  rotates  one  revolution  in  the  oppo
site  direction.

5. Observe the pattern on the ring gear teeth and

compare this with figure 27.

ADJUSTM ENTS AFFECTING

TOOTH CONTACT

Two adjustments can be made that affect tooth con

tact pattern; backlash and pinion depth. The effects of

bearing  preloads  are  not  readily  apparent  on  hand  load
ed  tooth  contact  pattern  tests.  However,  these  adjust
ments  should  be  within  specifications  before  proceeding

with backlash and drive pinion adjustments.

The position of the drive pinion is adjusted by

increasing  or  decreasing  the  distance  between  the  pin
ion  head  and  the  centerline  of the  ring  gear.  Decreasing
the  distance  will  move  the  pinion  closer  to  the  center-
line  of  the  ring  gear.  Increasing  the  distance  will  move

chevrolet truck Light Duty Truck 1994 Series, Repair Manual

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