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I f t h e o r i g i n a l t h e d r i v e p i n i o n g e a r s h a f t r e a r
b e a r i n g a n d a r e p l a c e m e n t
front
b e a r i n g
a r e
u s e d , w i t h a m i n i m u m o f 285 N*m (210
ft-lbs)
t o r q u e , t h e c o r r e c t b e a r i n g " p r e l o a d " t o r q u e i s 1
N»m (10 i n - l b s ) t o r q u e i n a d d i t i o n t o t h e t o r q u e
r e c o r d e d d u r i n g d i s a s s e m b l y .
Fig. 35 Drive Pinion Gear Shaft Bearing "Preload"
Torque Measurement
T h e b e a r i n g " p r e l o a d " t o r q u e s h o u l d be c o n -
s t a n t d u r i n g a c o m p l e t e r e v o l u t i o n o f t h e d r i v e
p i n i o n g e a r s h a f t . I f t h e " p r e l o a d " t o r q u e v a r i e s
d u r i n g r o t a t i o n o f t h e s h a f t , t h i s i n d i c a t e s a n i n -
t e r n a l " b i n d i n g " c o n d i t i o n a n d i t m u s t b e c o r -
r e c t e d b e f o r e c o n t i n u i n g w i t h t h e a s s e m b l y
o f
t h e d i f f e r e n t i a l .
(34) I f the specified b e a r i n g "preload" torque is not
obtained w i t h 285 N
#
m (210 ft-lbs) torque, continue
t i g h t e n i n g the drive p i n i o n gear shaft n u t i n s m a l l
increments u n t i l the correct bearing "preload" torque
is obtained.
T h e a s s e m b l y o f t h e d i f f e r e n t i a l is u n a c c e p t -
a b l e i f t h e f i n a l d r i v e p i n i o n g e a r s h a f t n u t
t o r q u e i s less t h a n 285 N * m (210 ft-lbs) t o r q u e o r
i f t h e d r i v e p i n i o n g e a r s h a f t b e a r i n g " p r e l o a d "
t o r q u e is n o t c o r r e c t .
(35) A p p l y a coating of gear l u b r i c a n t to the differ-
e n t i a l bearings, the b e a r i n g cups and the threaded
adjusters. Carefully position the assembled differen-
t i a l case i n the housing.
(36) Note the i n s t a l l a t i o n reference m a r k s and i n -
s t a l l t h e differential b e a r i n g caps at their, original lo-
cations.
(37) I n s t a l l the b e a r i n g cap bolts. T i g h t e n the up-
per bolts w i t h 14 N«m (10 ft-lbs) torque. Tighten t h e
lower
bolts " f i n g e r - t i g h t " u n t i l
the bolt head
is
l i g h t l y "seated" on the bearing cap.
DIFFERENTIAL
BEARING
"PRELOAD"
TORQUE
AND RING GEAR
"BACKLASH"
ADJUSTMENT
There are precautions t h a t m u s t be observed w h e n
adjusting the differential bearing "preload" torque
and the r i n g gear "backlash":
• the m a x i m u m permissible r i n g gear " b a c k l a s h "
v a r i a t i o n is 0.003 i n c h ;
• for example, i f t h e m i n i m u m " b a c k l a s h " is 0.006
inch a t one location, the m a x i m u m can be no more
t h a n 0.009 i n c h a t another location;
• t h i s v a r i a t i o n represents the m a x i m u m permissi-
ble " r u n o u t " and i t is i m p o r t a n t to index t h e gears so
t h a t the same teeth are engaged d u r i n g a l l "back-
l a s h " measurements;
• i t is also i m p o r t a n t to m a i n t a i n the
specified
threaded adjuster torque w h i l e adjusting t h e differ-
e n t i a l bearing "preload" torque and the r i n g gear
"backlash";
• excessive torque w i l l introduce a h i g h bearing
" l o a d " and cause premature bearing failure, w h i l e i n -
sufficient torque w i l l not support the r i n g gear cor-
rectly and t h i s can result i n excessive differential
case "free-play" and r i n g gear noise.
T h e d i f f e r e n t i a l b e a r i n g c u p s w i l l n o t
a l w a y s
r e s p o n d d i r e c t l y t o a d j u s t m e n t o f t h e t h r e a d e d
a d j u s t e r s , t h e r e f o r e t o e n s u r e a c c u r a t e a d j u s t -
m e n t r e s p o n s e s a n d t o m a i n t a i n t h e g e a r m e s h
i n d e x , t h e b e a r i n g s m u s t b e " s e a t e d " b y r o t a t i n g
t h e d r i v e p i n i o n g e a r s h a f t a h a l f t u r n i n e a c h
d i r e c t i o n
f i v e
t o
t e n
t i m e s
e a c h
t i m e
t h e
t h r e a d e d a d j u s t e r s a r e a d j u s t e d .
(1) Use Tool C-4164 to adjust each threaded ad-
j u s t e r i n w a r d (Fig. 36) u n t i l the excessive differential
bearing "free-play" is eliminated, b u t w i t h some r i n g
gear "backlash" (approximately 0.010 inch) r e m a i n -
i n g between the r i n g gear and drive p i n i o n gear.
"Seat" the bearing rollers as described above.
(2) I n s t a l l D i a l Indicator Tool C-3339 (Fig. 37) and
position the plunger against the drive side of a r i n g
gear tooth. Measure the " b a c k l a s h " at 4 positions
around the perimeter of the r i n g gear ( w i t h a n arc
i n t e r v a l of approximately 90 degrees between
each
position) to locate t h e area of m i n i m u m "backlash".
(3) After the measurement is completed, rotate t h e
r i n g gear to the position of least " b a c k l a s h " (as i n d i -
cated by the d i a l indicator pointer) and m a r k the
gear so t h a t a l l f u t u r e "backlash" measurements w i l l
be t a k e n w i t h the same teeth meshed.
(4) Loosen the right-side threaded adjuster and
t i g h t e n the left-side threaded adjuster u n t i l the r i n g
gear "backlash" is 0.003 to 0.004 i n c h (0.08 to 0.10
m m ) after each adjuster has been tightened w i t h 14
N»m (10 ft-lbs) torque. "Seat" the bearing rollers as
described above.
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