Chevrolet Chevelle 1977 Repair Manual page 108

4B-36
Fig. 26C—Gear Tooth N om enclature
4. E xpand brake shoes until a torque o f 20-30 lb. ft. is
required to turn the pinion.
N O T E : A test m ade w ithout loading the
gears will not give a satisfactory p attern .
T urn com panion flange w ith w rench so th at
ring gear rotates one full revolution then
reverse rotation so th at rin g gear rotates one
revolution in opposite direction. Excessive
turning o f ring gear is not recom m ended.
5. O bserve pattern on ring g ear teeth and com pare
w ith Figure 27C.
OVERHAUL MANUAL
Adjustments Affecting Tooth Contact
Two adjustm ents can be m ade w hich will affect tooth
contact p attern . These are backlash and position o f drive
pinion in carrier. The effects o f b earin g prelo ads are not
readily ap p aren t on hand loaded teeth p a tte rn tests:
however, these adjustm ents should be w ithin specifica­
tions before proceeding w ith backlash and drive pinion
adjustm ents.
N O TE: It m ay be necessary to adjust both
pinion dep th and backlash to ob tain the
correct p attern.
The position
increasing or decreasing the shim thickness betw een the
pinion head and in n er race o f re a r bearing. The shim is
used in the differential to com pensate for m anu factu rin g
tolerances. Increasing shim
pinion closer to centerline o f the rin g gear. D ecreasing
shim thickness will move p inion fa rth e r away from
centerline o f the ring gear.
Backlash is adjusted by m eans o f the side bearing
adjusting shim s w hich moves the en tire case and ring
gear assem bly closer to, or fa rth e r from the drive pinion.
(The adjusting shim s are also used to set side bearing
preload). To increase backlash, increase rig h t shim and
decrease left
backlash, decrease right shim and increase left shim an
equal am ount.
The im p o rtan t thing to note is th a t the contact p attern is
centrally located up and down on the face o f the ring
gear teeth.
o f the drive p in io n is
thickness will move the
shim an equal am ount.
adjusted by
To decrease