sets only. The identifying numbers for the ring and
pinion gear are etched into the face of each gear (Fig.
1). A plus (+) number, minus (–) number or zero (0) is
etched into the face of the pinion gear. This number
is the amount (in thousandths of an inch) the depth
varies from the standard depth setting of a pinion
etched with a (0). The standard setting from the cen-
ter line of the ring gear to the back face of the pinion
is 92.1 mm (3.625 in.). The standard depth provides
the best gear tooth contact pattern. Refer to Back-
lash and Contact Pattern Analysis paragraph in this
section for additional information.

Compensation

for

pinion

depth

variance

achieved with a select shim/oil baffle. The shims are
placed between the rear pinion bearing and the pin-
ion gear head (Fig. 2).

If a new gear set is being installed, note the depth

variance etched into both the original and replace-
ment pinion. Add or subtract this number from the
thickness of the original depth shim/oil slinger to
compensate for the difference in the depth variances.
Refer to the Pinion Gear Depth Variance chart.

Note where Old and New Pinion Marking columns

intersect.

Intersecting

figure

represents

plus

minus the amount needed.

Note the etched number on the face of the pinion

gear head (–1, –2, 0, +1, +2, etc.). The numbers rep-
resent thousands of an inch deviation from the stan-
dard. If the number is negative, add that value to the
required thickness of the depth shims. If the number
is positive, subtract that value from the thickness of
the depth shim. If the number is 0 no change is nec-
essary.

DIFFERENTIAL & DRIVELINE

3s - 1

2001 JEEP GRAND CHEROKEE

PINION GEAR DEPTH VARIANCE

Original Pinion

Gear Depth

Variance

Replacement Pinion Gear Depth Variance

+0.008

+0.007

+0.006

+0.005

+0.004

+0.003

+0.002

+0.001

+0.007

+0.006

+0.005

+0.004

+0.003

+0.002

+0.001

0.001

+0.006

+0.005

+0.004

+0.003

+0.002

+0.001

0.001

0.002

+0.005

+0.004

+0.003

+0.002

+0.001

0.001

0.002

0.003

+0.004

+0.003

+0.002

+0.001

0.001

0.002

0.003

0.004

+0.003

+0.002

+0.001

0.001

0.002

0.003

0.004

0.005

+0.002

+0.001

0.001

0.002

0.003

0.004

0.005

0.006

+0.001

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

PINION DEPTH MEASUREMENT

Measurements are taken with pinion bearing cups

and pinion bearings installed in the housing. Take
measurements with Pinion Gauge Set and Dial Indi-
cator C-3339 (Fig. 3).

(1) Assemble Pinion Height Block 6739, Pinion

Block 6733 and rear pinion bearing onto Screw 6741
(Fig. 3).

(2) Insert assembled height gauge components,

rear bearing and screw into the housing through pin-
ion bearing cups (Fig. 4).

(3) Install front pinion bearing and Cone-nut 6740

hand tight (Fig. 3).

(4) Place Arbor Disc 6732 on Arbor D-115-3 in posi-

tion, in the housing side bearing cradles (Fig. 5).
Install differential bearing caps on Arbor Discs and
tighten cap bolts to 41 N·m (30 ft. lbs.).

NOTE: Arbor Discs 6732 has different step diame-
ters to fit other axles. Choose proper step for axle
being serviced.

(5) Assemble Dial Indicator C-3339 into Scooter

Block D-115-2 and secure set screw.

Fig. 1 Pinion Gear ID Numbers

1 - PRODUCTION NUMBERS
2 - DRIVE PINION GEAR DEPTH VARIANCE
3 - GEAR MATCHING NUMBER

Fig. 2 Adjustment Shims Locations

1 - PINION GEAR DEPTH SHIM/OIL BAFFLE
2 - DIFFERENTIAL BEARING SHIM
3 - RING GEAR
4 - DIFFERENTIAL BEARING SHIM
5 - COLLAPSIBLE SPACER

3s - 2

FRONT AXLE - 186FBI

FRONT AXLE - 186FBI (Continued)

2001 JEEP GRAND CHEROKEE

(6) Place Scooter Block/Dial Indicator in position

in axle housing so dial probe and scooter block are
flush against the rearward surface of the pinion
height block (Fig. 3). Hold scooter block in place and

zero the dial indicator face to the pointer. Tighten
dial indicator face lock screw.

(7) With scooter block still in position against the

pinion height block, slowly slide the dial indicator
probe over the edge of the pinion height block.

(8) Slide the dial indicator probe across the gap

between the pinion height block and the arbor bar
with the scooter block against the pinion height block
(Fig. 6). When the dial probe contacts the arbor bar,
the dial pointer will turn clockwise. Continue moving
the dial probe to the crest of the arbor bar and record
the highest reading. If the dial indicator can not
achieve the zero reading, the rear bearing cup or the
pinion depth gauge set is not installed correctly.

(9) Select a shim/oil baffle equal to the dial indica-

tor reading plus the pinion depth variance number
etched in the face of the pinion (Fig. 1). For example,
if the depth variance is –2, add +0.002 in. to the dial
indicator reading.

DIFFERENTIAL

Differential side bearing preload and gear backlash

is achieved by selective shims positioned behind the
differential side bearing cones. The proper shim
thickness can be determined using slip-fit Dummy
Bearings D-348 in place of the differential side bear-
ings and a Dial Indicator C-3339. Before proceeding
with the differential bearing preload and gear back-
lash measurements, measure the pinion gear depth
and prepare the pinion for installation. Establishing
proper pinion gear depth is essential to establishing
gear backlash and tooth contact patterns. After the
overall shim thickness to take up differential side
play is measured, the pinion is installed, and the

Fig. 3 Pinion Gear Depth Tools

1 - DIAL INDICATOR
2 - ARBOR
3 - PINION HEIGHT BLOCK
4 - CONE
5 - SCREW
6 - PINION BLOCK
7 - SCOOTER BLOCK
8 - ARBOR DISC

Fig. 4 Pinion Height Block

1 - PINION BLOCK
2 - PINION HEIGHT BLOCK

Fig. 5 Tools In Housing

1 - ARBOR DISC - 6732
2 - PINION BLOCK - 6733
3 - ARBOR - D-115-3
4 - PINION HEIGHT BLOCK - 6739

FRONT AXLE - 186FBI

3s - 3

FRONT AXLE - 186FBI (Continued)

2001 JEEP GRAND CHEROKEE

gear backlash shim thickness is measured. The over-
all shim thickness is the total of the dial indicator
reading and the preload specification added together.
The gear backlash measurement determines the
thickness of the shim used on the ring gear side of
the differential case. Subtract the gear backlash shim
thickness from the total overall shim thickness and
select that amount for the pinion gear side of the dif-
ferential (Fig. 7). Differential shim measurements
are performed with spreader W-129-B removed.

SHIM SELECTION

NOTE: It is difficult to salvage the differential side
bearings during the removal procedure. Install
replacement bearings if necessary.

(1) Remove differential side bearings from differ-

ential case.

(2) Install ring gear on differential case and

tighten bolts to specification.

(3) Install dummy side bearings D-348 on differen-

tial case.

(4) Install differential case in the housing.

CAUTION: When installing a Vari-Lok™ differential,
the oil feed tube must be pointed to the bottom of
the housing. If differential is forced in with the oil
feed towards the top, the anti-rotation tabs will be
damaged.

(5) Record the thickness of Dummy Shims 8107.

Insert the shims between the dummy bearings and
the differential housing (Fig. 8).

(6) Install the marked bearing caps in their correct

positions. Install and snug the bolts (Fig. 9).

(7) Using a dead-blow hammer, seat the differen-

tial dummy bearings to each side of the axle housing
(Fig. 10) and (Fig. 11).

Fig. 6 Pinion Gear Depth Measurement

1 - ARBOR
2 - SCOOTER BLOCK
3 - DIAL INDICATOR

Fig. 7 Adjustment Shims Locations

1 - PINION GEAR DEPTH SHIM/OIL BAFFLE
2 - DIFFERENTIAL BEARING SHIM
3 - RING GEAR
4 - DIFFERENTIAL BEARING SHIM
5 - COLLAPSIBLE SPACER

Fig. 8 Dummy Shim Location

1 - DUMMY SHIM
2 - AXLE HOUSING
3 - DIFFERENTIAL CASE
4 - DUMMY BEARINGS

3s - 4

FRONT AXLE - 186FBI

FRONT AXLE - 186FBI (Continued)

2001 JEEP GRAND CHEROKEE

Content .. 698 699 700 701 ..