2001 DODGE RAM height

PINION GEAR DEPTH VARIANCE
Original Pinion
Gear Depth
VarianceReplacement Pinion Gear Depth Variance
þ4 þ3 þ2 þ1 0 +1 +2 +3 +4
+4+0.008 +0.007 +0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0
+3+0.007 +0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0 þ0.001
+2+0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0 þ0.001 þ0.002
+1+0.005 +0.004 +0.003 +0.002 +0.001 0 þ0.001 þ0.002 þ0.003
0+0.004 +0.003 +0.002 +0.001 0 þ0.001 þ0.002 þ0.003 þ0.004
þ1+0.003 +0.002 +0.001 0 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005
þ2+0.002 +0.001 0 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005 þ0.006
þ3+0.001 0 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005 þ0.006 þ0.007
þ40 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005 þ0.006 þ0.007 þ0.008
PINION DEPTH MEASUREMENT AND ADJUSTMENT
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. 6).(1) Assemble Pinion Height Block 6739, Pinion
Block 6736 and rear pinion bearing onto Screw 6741
(Fig. 6).
(2) Insert assembled height gauge components,
rear bearing and screw into the housing through pin-
ion bearing cups (Fig. 7).
(3) Install front pinion bearing and Cone-nut 6740
hand tight (Fig. 6).
(4) Place Arbor Disc 6732 on Arbor D-115-3 in posi-
tion in the housing side bearing cradles (Fig. 8).
NOTE: Arbor Discs 6732 has different step diame-
ters to fit other axles. Choose proper step for axle
being serviced.
Fig. 6 Pinion Gear Depth Gauge Tools
1 - DIAL INDICATOR
2 - ARBOR
3 - PINION HEIGHT BLOCK
4 - CONE
5 - SCREW
6 - PINION BLOCK
7 - SCOOTER BLOCK
8 - ARBOR DISC
Fig. 7 Pinion Height Block
1 - PINION BLOCK
2 - PINION HEIGHT BLOCK
BR/BEREAR AXLE - 248RBI 3 - 115
REAR AXLE - 248RBI (Continued)

(5) Install differential bearing caps on arbor discs
and snug the bearing cap bolts. Then cross tighten
cap bolts to 108 N´m (80 ft. lbs.).
(6) Assemble Dial Indicator C-3339 into Scooter
Block D-115-2 and secure set screw.
(7) Place Scooter Block/Dial Indicator in position
in the housing so dial probe and scooter block are
flush against the rearward surface of the pinion
height block (Fig. 6). Hold scooter block in place and
zero the dial indicator face to the pointer. Tighten
dial indicator face lock screw.
(8) 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.
(9) 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. 9). When the dial probe contacts the arbor bar,
the dial pointer will turn clockwise. Bring dial
pointer back to zero against the arbor bar, do not
turn dial face. 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.
(10) Select a shim/oil baffle equal to the dial indi-
cator reading plus the pinion depth variance number
etched in the face of the pinion (Fig. 4). For example,
if the depth variance is ±2, add +0.002 in. to the dial
indicator reading.
DIFFERENTIAL SIDE BEARING PRELOAD AND
GEAR BACKLASH
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-343 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
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. 10). 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.
Fig. 8 Gauge Tools In Housing
1 - ARBOR DISC
2 - PINION BLOCK
3 - ARBOR
4 - PINION HEIGHT BLOCK
Fig. 9 Pinion Gear Depth Measurement
1 - ARBOR
2 - SCOOTER BLOCK
3 - DIAL INDICATOR
3 - 116 REAR AXLE - 248RBIBR/BE
REAR AXLE - 248RBI (Continued)

PINION GEAR DEPTH VARIANCE
Original Pinion
Gear Depth
VarianceReplacement Pinion Gear Depth Variance
þ4 þ3 þ2 þ1 0 +1 +2 +3 +4
+4+0.008 +0.007 +0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0
+3+0.007 +0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0 þ0.001
+2+0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0 þ0.001 þ0.002
+1+0.005 +0.004 +0.003 +0.002 +0.001 0 þ0.001 þ0.002 þ0.003
0+0.004 +0.003 +0.002 +0.001 0 þ0.001 þ0.002 þ0.003 þ0.004
þ1+0.003 +0.002 +0.001 0 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005
þ2+0.002 +0.001 0 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005 þ0.006
þ3+0.001 0 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005 þ0.006 þ0.007
þ40 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005 þ0.006 þ0.007 þ0.008
PINION DEPTH MEASUREMENT AND ADJUSTMENT
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. 6).(1) Assemble Pinion Height Block 6739, Pinion
Block 6737 and rear pinion bearing onto Screw 6741
(Fig. 6).
(2) Insert assembled height gauge components,
rear bearing and screw into the housing through pin-
ion bearing cups (Fig. 7).
(3) Install front pinion bearing and Cone-nut 6740
hand tight (Fig. 6).
(4) Place Arbor Disc 6732 on Arbor D-115-3 in posi-
tion in the housing side bearing cradles (Fig. 8).
NOTE: Arbor Discs 6732 has different step diame-
ters to fit other axles. Choose proper step for axle
being serviced.
Fig. 6 Pinion Gear Depth Gauge Tools
1 - DIAL INDICATOR
2 - ARBOR
3 - PINION HEIGHT BLOCK
4 - CONE
5 - SCREW
6 - PINION BLOCK
7 - SCOOTER BLOCK
8 - ARBOR DISC
Fig. 7 Pinion Height Block
1 - PINION BLOCK
2 - PINION HEIGHT BLOCK
3 - 146 REAR AXLE - 267RBIBR/BE
REAR AXLE - 267RBI (Continued)

(5) Install differential bearing caps on arbor discs
and snug the bearing cap bolts. Then cross tighten
cap bolts to 108 N´m (80 ft. lbs.).
(6) Assemble Dial Indicator C-3339 into Scooter
Block D-115-2 and secure set screw.
(7) Place Scooter Block/Dial Indicator in position
in the housing so dial probe and scooter block are
flush against the rearward surface of the pinion
height block (Fig. 6). Hold scooter block in place and
zero the dial indicator face to the pointer. Tighten
dial indicator face lock screw.
(8) 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.
(9) 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. 9). When the dial probe contacts the arbor bar,
the dial pointer will turn clockwise. Bring dial
pointer back to zero against the arbor bar, do not
turn dial face. 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.
(10) Select a shim/oil baffle equal to the dial indi-
cator reading plus the pinion depth variance number
etched in the face of the pinion (Fig. 4). For example,
if the depth variance is ±2, add +0.002 in. to the dial
indicator reading.
DIFFERENTIAL SIDE BEARING PRELOAD AND
GEAR BACKLASH
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-343 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
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. 10). 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.
Fig. 8 Gauge Tools In Housing
1 - ARBOR DISC
2 - PINION BLOCK
3 - ARBOR
4 - PINION HEIGHT BLOCK
Fig. 9 Pinion Gear Depth Measurement
1 - ARBOR
2 - SCOOTER BLOCK
3 - DIAL INDICATOR
BR/BEREAR AXLE - 267RBI 3 - 147
REAR AXLE - 267RBI (Continued)

PINION GEAR DEPTH VARIANCE
Original Pinion
Gear Depth
VarianceReplacement Pinion Gear Depth Variance
þ4 þ3 þ2 þ1 0 +1 +2 +3 +4
+4+0.008 +0.007 +0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0
+3+0.007 +0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0 þ0.001
+2+0.006 +0.005 +0.004 +0.003 +0.002 +0.001 0 þ0.001 þ0.002
+1+0.005 +0.004 +0.003 +0.002 +0.001 0 þ0.001 þ0.002 þ0.003
0+0.004 +0.003 +0.002 +0.001 0 þ0.001 þ0.002 þ0.003 þ0.004
þ1+0.003 +0.002 +0.001 0 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005
þ2+0.002 +0.001 0 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005 þ0.006
þ3+0.001 0 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005 þ0.006 þ0.007
þ40 þ0.001 þ0.002 þ0.003 þ0.004 þ0.005 þ0.006 þ0.007 þ0.008
PINION DEPTH MEASUREMENT AND ADJUSTMENT
Measurements are taken with pinion cups and pin-
ion bearings installed in housing. Take measure-
ments with a Pinion Gauge Set 6730 and Dial
Indicator C-3339 (Fig. 6).(1) Assemble Pinion Height Block 6739, Pinion
Block 6738 and rear pinion bearing onto Screw 6741
(Fig. 6).
(2) Insert assembled height gauge components,
rear bearing and screw into the housing through pin-
ion bearing cups (Fig. 7).
(3) Install front pinion bearing and Cone 6740
hand tight (Fig. 6).
(4) Place Arbor Disc 6732 on Arbor D-115-3 in posi-
tion in the housing side bearing cradles (Fig. 8).
Install differential bearing caps on Arbor Discs and
snug the bearing cap bolts. Then tighten cap bolts in
a criss-cross pattern to 108 N´m (80 ft. lbs.).
NOTE: Arbor Discs 6732 have different step diame-
ters to fit other axle sizes. Pick correct size step for
axle being serviced.
Fig. 6 Pinion Gear Depth Gauge
1 - DIAL INDICATOR
2 - ARBOR
3 - PINION HEIGHT BLOCK
4 - CONE
5 - SCREW
6 - PINION BLOCK
7 - SCOOTER BLOCK
8 - ARBOR DISC
Fig. 7 Pinion Height Block
1 - PINION BLOCK
2 - PINION HEIGHT BLOCK
BR/BEREAR AXLE - 286RBI 3 - 175
REAR AXLE - 286RBI (Continued)

(5) Assemble Dial Indicator C-3339 into Scooter
Block D-115-2 and secure set screw.
(6) Place Scooter Block/Dial Indicator in position
in the housing so dial probe and scooter block are
flush against the surface of the pinion height block.
Hold scooter block in place and zero the dial indica-
tor 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.
Observe how many revolutions counterclockwise the
dial pointer travels (approximately 0.125 in.) to the
out-stop of the dial indicator.
(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. 9). When the dial probe contacts the arbor bar,
the dial pointer will turn clockwise. Bring dial
pointer back to zero against the arbor bar, do not
turn dial face. 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 equal to the dial indicator read-
ing plus the drive pinion gear depth variance number
etched in the face of the pinion gear (Fig. 4) using
the opposite sign on the variance number. For exam-
ple, if the depth variance is ±2, add +0.002 in. to the
dial indicator reading.
(10) Remove the pinion depth gauge components
from the axle housingDIFFERENTIAL BEARING PRELOAD AND GEAR
BACKLASH
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-346 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 gear for installation. Estab-
lishing proper pinion gear depth is essential to estab-
lishing gear backlash and tooth contact patterns.
After the overall shim thickness to take up differen-
tial side play is measured, the pinion gear is
installed, and the gear backlash shim thickness is
measured. The overall shim thickness is the total of
the dial indicator reading and the preload specifica-
tion 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 differential (Fig. 10). Differential
shim measurements are performed with axle
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.
Fig. 8 Gauge Tools In Housing
1 - ARBOR DISC
2 - PINION BLOCK
3 - ARBOR
4 - PINION HEIGHT BLOCKFig. 9 Pinion Gear Depth Measurement
1 - ARBOR
2 - SCOOTER BLOCK
3 - DIAL INDICATOR
3 - 176 REAR AXLE - 286RBIBR/BE
REAR AXLE - 286RBI (Continued)

WARNING
WARNING: DUST AND DIRT ACCUMULATING ON
BRAKE PARTS DURING NORMAL USE MAY CON-
TAIN ASBESTOS FIBERS FROM PRODUCTION OR
AFTERMARKET LININGS. BREATHING EXCESSIVE
CONCENTRATIONS OF ASBESTOS FIBERS CAN
CAUSE SERIOUS BODILY HARM. EXERCISE CARE
WHEN SERVICING BRAKE PARTS. DO NOT CLEAN
BRAKE PARTS WITH COMPRESSED AIR OR BY
DRY BRUSHING. USE A VACUUM CLEANER SPE-
CIFICALLY DESIGNED FOR THE REMOVAL OF
ASBESTOS FIBERS FROM BRAKE COMPONENTS.
IF A SUITABLE VACUUM CLEANER IS NOT AVAIL-
ABLE, CLEANING SHOULD BE DONE WITH A
WATER DAMPENED CLOTH. DO NOT SAND, OR
GRIND BRAKE LINING UNLESS EQUIPMENT USED
IS DESIGNED TO CONTAIN THE DUST RESIDUE.
DISPOSE OF ALL RESIDUE CONTAINING ASBES-
TOS FIBERS IN SEALED BAGS OR CONTAINERS
TO MINIMIZE EXPOSURE TO YOURSELF AND OTH-
ERS. FOLLOW PRACTICES PRESCRIBED BY THE
OCCUPATIONAL SAFETY AND HEALTH ADMINIS-
TRATION AND THE ENVIRONMENTAL PROTECTION
AGENCY FOR THE HANDLING, PROCESSING, AND
DISPOSITION OF DUST OR DEBRIS THAT MAY
CONTAIN ASBESTOS FIBERS.
CAUTION: Never use gasoline, kerosene, alcohol,
motor oil, transmission fluid, or any fluid containing
mineral oil to clean the system components. These
fluids damage rubber cups and seals. Use only
fresh brake fluid or Mopar brake cleaner to clean or
flush brake system components. These are the only
cleaning materials recommended. If system contam-
ination is suspected, check the fluid for dirt, discol-
oration, or separation into distinct layers. Also
check the reservoir cap seal for distortion. Drain
and flush the system with new brake fluid if con-
tamination is suspected.
CAUTION: Use Mopar brake fluid, or an equivalent
quality fluid meeting SAE/DOT standards J1703 and
DOT 3. Brake fluid must be clean and free of con-
taminants. Use fresh fluid from sealed containers
only to ensure proper antilock component opera-
tion.
CAUTION: Use Mopar multi-mileage or high temper-
ature grease to lubricate caliper slide surfaces,
drum brake pivot pins, and shoe contact points on
the backing plates. Use multi-mileage grease or GE
661 or Dow 111 silicone grease on caliper slide pins
to ensure proper operation.
DIAGNOSIS AND TESTING - BASE BRAKE
SYSTEM
Base brake components consist of the brake shoes,
calipers, wheel cylinders, brake drums, rotors, brake
lines, master cylinder, booster, and parking brake
components.
Brake diagnosis involves determining if the prob-
lem is related to a mechanical, hydraulic, or vacuum
operated component.
The first diagnosis step is the preliminary check.
PRELIMINARY BRAKE CHECK
(1) Check condition of tires and wheels. Damaged
wheels and worn, damaged, or underinflated tires
can cause pull, shudder, vibration, and a condition
similar to grab.
(2) If complaint was based on noise when braking,
check suspension components. Jounce front and rear
of vehicle and listen for noise that might be caused
by loose, worn or damaged suspension or steering
components.
(3) Inspect brake fluid level and condition. Note
that the brake reservoir fluid level will decrease in
proportion to normal lining wear.Also note that
brake fluid tends to darken over time. This is
normal and should not be mistaken for contam-
ination.
(a) If fluid level is abnormally low, look for evi-
dence of leaks at calipers, wheel cylinders, brake
lines, and master cylinder.
(b) If fluid appears contaminated, drain out a
sample to examine. System will have to be flushed
if fluid is separated into layers, or contains a sub-
stance other than brake fluid. The system seals
and cups will also have to be replaced after flush-
ing. Use clean brake fluid to flush the system.
(4) Check parking brake operation. Verify free
movement and full release of cables and pedal. Also
note if vehicle was being operated with parking
brake partially applied.
(5) Check brake pedal operation. Verify that pedal
does not bind and has adequate free play. If pedal
lacks free play, check pedal and power booster for
being loose or for bind condition. Do not road test
until condition is corrected.
(6) Check booster vacuum check valve and hose.
(7) If components checked appear OK, road test
the vehicle.
ROAD TESTING
(1) If complaint involved low brake pedal, pump
pedal and note if it comes back up to normal height.
(2) Check brake pedal response with transmission
in Neutral and engine running. Pedal should remain
firm under constant foot pressure.
BR/BEBRAKES 5 - 5
HYDRAULIC/MECHANICAL (Continued)

The drum forces both brake shoes to move in the
same direction of rotation. Servo action begins with
the primary brake shoe which begins to wedge (or
wrap) itself against the rotating drum surface. This
force is transmitted equally to the secondary brake
shoe through the adjuster screw and anchor pin. The
net result is that each shoe helps the other exert
extra force against the drum. It is servo action that
creates the wedging (or wrap) effect which produces
increased force on the drum braking surface.
All drum brake assemblies are equipped with a self
adjusting mechanism. The components forming the
mechanism consist of the: adjuster screw, adjuster
lever, actuating lever (11 inch brake), lever return
spring and the adjuster lever spring. The adjuster
lever on the 12 inch brake, is also equipped with a
lever and tension spring.
The adjuster mechanism performs two important
functions. First, is in maintaining proper brake shoe
operating clearance. And second, is to maintain brake
pedal height. The mechanism does so, by adjusting
the shoes in small increments to compensate for lin-
ing wear. The adjustment process is continuous
throughout the useful life of the brake lining.
The adjuster components are all connected to the
secondary brake shoes. Actual adjustment only
occurs during reverse brake stops. Secondary brake
shoe movement (during reverse stops), is what acti-
vates the adjuster components.
In operation, secondary shoe movement causes the
adjuster lever spring to exert pull on the lever. This
pivots the lever away from the adjuster screw teeth.
When the stop is completed and the brakes released,
the adjuster lever pivots back to a normal position. It
is during this return movement of the lever when
adjustment occurs. At this point, the lever comes
back into contact with the adjuster screw teeth as it
moves upward. The lever will then rotate the
adjuster screw one or two teeth as needed for adjust-
ment.
NOTE: The adjustment process requires a complete
stop to actually occur. Rolling stops will NOT acti-
vate the adjuster components. In addition, the
adjuster screws are left and right hand parts and
must NOT be interchanged.
DIAGNOSIS AND TESTING - BRAKE DRUM
The maximum allowable diameter of the drum
braking surface is indicated on the drum outer edge.
Generally, a drum can be machined to a maximum of
1.52 mm (0.060 in.) oversize. Always replace the
drum if machining would cause drum diameter to
exceed the size limit indicated on the drum.
BRAKE DRUM RUNOUT
Measure drum diameter and runout with an accu-
rate gauge. The most accurate method of measure-
ment involves mounting the drum in a brake lathe
and checking variation and runout with a dial indi-
cator.
Variations in drum diameter should not exceed
0.069 mm (0.0028 in.). Drum runout should not
exceed 0.18 mm (0.007 in.) out of round. Machine the
drum if runout or variation exceed these values.
Replace the drum if machining causes the drum to
exceed the maximum allowable diameter.
STANDARD PROCEDURE - BRAKE DRUM
MACHINING
The brake drums can be machined on a drum lathe
when necessary. Initial machining cuts should be lim-
ited to 0.12 - 0.20 mm (0.005 - 0.008 in.) at a time as
heavier feed rates can produce taper and surface
variation. Final finish cuts of 0.025 to 0.038 mm
(0.001 to 0.0015 in.) are recommended and will gen-
erally provide the best surface finish.
Be sure the drum is securely mounted in the lathe
before machining operations. A damper strap should
always be used around the drum to reduce vibration
and avoid chatter marks.
The maximum allowable diameter of the drum
braking surface is stamped or cast into the drum
outer edge.
CAUTION: Replace the drum if machining will cause
the drum to exceed the maximum allowable diame-
ter.
CLEANING
Clean the individual brake components, including
the support plate and wheel cylinder exterior, with a
water dampened cloth or with brake cleaner. Do not
use any other cleaning agents. Remove light rust and
scale from the brake shoe contact pads on the sup-
port plate with fine sandpaper.
INSPECTION
As a general rule, riveted brake shoes should be
replaced when worn to within 0.78 mm (1/32 in.) of
the rivet heads. Bonded lining should be replaced
when worn to a thickness of 1.6 mm (1/16 in.).
Examine the lining contact pattern to determine if
the shoes are bent or the drum is tapered. The lining
should exhibit contact across its entire width. Shoes
exhibiting contact only on one side should be
replaced and the drum checked for runout or taper.
Inspect the adjuster screw assembly. Replace the
assembly if the star wheel or threads are damaged,
or the components are severely rusted or corroded.
BR/BEBRAKES 5 - 33
DRUM (Continued)