Component
(Item / Condition)
Investigation Specs Procedure What To Replace
Consumable Items: These are considered to be normal wear items and should be repaired as part of regular preventive maintenance.
Disc Brake Pads
A
Worn
Measure the thickness of the total pad
(friction material and backing plate).
Pads must be replaced when they
reach 0.433 in. (11 mm).
Section 4.3
Replace the pads on both
sides of the worn axle.
B
Uneven wear
on single pad
Measure the thickness of the total pad in
at least two (2) places at top and two (2)
places at bottom, at least 1/2 inch from
the edge.
The average difference of top vs.
bottom, or left vs. right, should be
no greater than 0.080 in. (2 mm).
Section 4.3.2
Replace the pads on both
sides of the worn axle and
replace the guide pins as
needed.
C
Uneven wear
on inboard vs.
outboard
Measure the pad thickness as described
for Item B, but also check guide pin wear
and slide-ability.
Average difference inboard to
outboard should be no greater
than 0.138 in (3.5 mm).
Section 4.3.3
D
Surface
damage
Inspect for minor chips near the edge
and cracks on face (permitted) vs. major
sections damaged or missing.
See Figure 24 in SD-23-7541. Section 4.3.3
Replace the pads on both
sides of the worn axle.
Boots & Seals
E Tears & cuts
Inspect the tappet and guide pin boots for
cuts, cracks, and tears.
Any damage must be repaired.
Sections
4.5.4 & 4.6.2
Replace the damaged boots
and replace the resultant
internal corroded guide pins
as needed.
F Melting
Inspect as Item E, but also check the
running clearance before removing the
brake pads.
Any damage must be repaired.
See Calipers
Item L
Guide Pins
G Binding
With the pads removed, the caliper should
move freely by hand. Re-torque the
carrier to torque plate bolts per the OE
spec and procedure, if binding.
See Figure 26 (slide) and Table 4
(torque) in SD-23-7541.
Sections
4.5.1 & 5.3
Replace the worn guide pins as
needed and replace the torque
plate if the re-torque procedure
does not resolve the issue.
H Excessive play
Feel for excessive play between the caliper
and the carrier.
See Figure 27 in SD-23-7541. Section 4.5.2
Replace the worn guide pins
as needed.
Rotors
I Worn
Measure the rotor thickness with a long
jaw caliper.
Thickness must be greater than
1.46 in. (37 mm).
Section 4.4
Refer to the OEM
recommendations for non-
Bendix
®
rotors. For Bendix
rotors, replace the rotors on
both sides of the axle.
J
Surface
damage
Minor cracks and grooves are acceptable,
but check for cracks over the outside
edge.
See Figure 25 in SD-23-7541 for
surface details.
Refer to the OEM
recommendations for non-
Bendix rotors. For Bendix
rotors only, replace the rotor
that is damaged.
Non-Serviceable: These are non-serviceable items and pending warranty terms; these issues may be covered under warranty.
Calipers
K
Adjuster
not rotating
If the 2
nd
sheer adapter breaks while
turning the 10mm box-end wrench
counterclockwise, the adjuster is seized.
Adjuster must turn in both
directions with a hand wrench.
Section 4.4
Caliper only must be replaced
with malfunctioning adjuster.
L
Adjuster
too tight,
dragging brake
With the brakes released, check the
running clearance between the tappet
and the inboard pad.
The gap should be between
0.024 in. (0.6 mm) and
0.043 in. (1.1 mm).
Section 4.1
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