Bendix® ADB22X®, ADB22X®-V, and ADB22X®-LT
Air Disc Brake Troubleshooting Guide
A troubleshooting flowchart is provided in SD-23-7541, Bendix® ADB22X®, ADB22X®-V, and ADB22X®- LT Air Disc Brakes, and should serve
as the process used for issue investigation. The points below provide a quick reference for common component questions, but is not a
replacement for the detailed procedures contained in the Service Data Sheet. Before starting work, refer to the General Safety Guidelines on
page 2 of the Service Data Sheet. Refer to B2Bendix.com.

Component
(Item / Condition)

Investigation

Specs from
SD-23-7541

Procedure from
SD-23-7541
Section

What To Replace

Disc Brake Pads

Consumable Items: These are considered to be normal wear items and should be repaired as part of regular preventive maintenance.
Measure the thickness of the
remaining friction material.

Pads must be replaced when they
reach 0.125 in. (3.2 mm) of friction
material.

3.3

B

Uneven wear on
single pad

Measure the thickness of the total pad
in at least two (2) places at the top
and two (2) places at the bottom, at
least 1/2 in. from the edge.

The average difference of top vs.
bottom or left vs. right should be no
greater than 0.080 in. (2 mm).

3.3.2

C

Uneven wear
on inboard vs.
outboard

Measure the pad thickness as
described for Item B above, 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).

3.3.3

See Figure 24.

3.3.3

A

Worn

Inspect for minor chips near the edge

D Surface damage and cracks on the face (permitted) vs.

Guide Pins

Boots and Seals

major sections damaged or missing.

Inspect the tappet and guide pin boots
for cuts, cracks, and tears.

Any damage must be repaired.

Melting

Inspect as Item E above, but also
check the running clearance before
removing the brake pads.

Any damage must be repaired.

G

Binding

With the pads removed, the caliper
should move freely by hand. Loosen
and re-torque the caliper to anchor
plate bolts per the OE spec and
procedure, if binding.

See Figure 25 (slide) and Table 4
(torque).

H

Excessive play

Feel for excessive play between the
caliper and the carrier.

See Figure 26.

E

Tears and cuts

F

Worn

Rotors

I

Measure the rotor thickness with a
long jaw caliper or Bendix® Pad/Rotor
Measuring Tool (K109114).

J

Surface damage

Replace the pads on both
sides of the worn axle and
replace the guide pins as
needed.

Replace the pads on both
sides of the worn axle.

3.5.4 and 3.6.2

2.2
and 3.6.1

3.5.1 and 4.3

3.5.2

Thickness must be greater than 1.46
in. (37 mm).
3.4

Minor cracks and grooves are
acceptable, but check for cracks over
the inside and outside edges.

Replace the pads on both
sides of the worn axle.

Replace the damaged
boots and replace the
resultant internal corroded
guide pins as needed.

Replace worn guide pins
as needed. If guidance
system binding still occurs,
replace caliper/carrier
assembly. Replace anchor
plate if new caliper/carrier
assembly does not resolve
issue.
Replace the worn guide
pins as needed.
Refer to the OEM
recommendations for
non-Bendix® rotors. For
Bendix rotors, replace the
rotors on both sides of
the axle.
Refer to the OEM
recommendations for nonBendix rotors. For Bendix
rotors only, replace the
rotor that is damaged.

See Figure 12 for surface details.

Calipers

Non-Serviceable: These are non-serviceable items and pending warranty terms; these issues may be covered under warranty.

K

Adjuster
not rotating

If the second shear adapter breaks
while turning the 10-mm box-end
wrench counterclockwise, the adjuster
is seized.

Adjuster must turn in both directions
with a hand wrench.

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 0.047 in.
(1.2 mm).

3.2

Caliper only must
be replaced with
malfunctioning adjuster.

3.1

Install and torque the
replacement caliper
per section 4.3.7.

®

®

Bendix ADB22X Troubleshooting Guide
C) Uneven Wear on Inboard vs. Outboard

A) Worn Pads
Flat Style Backing Plate “Stamped”
Bendix® BA236™/BX275™/BX283™
A

B

A

Non-Flat Style Backing Plate
“Cast” Bendix® BX276™/BX277™

B

Pads are OK if |B – A| < 3.5mm

Minimum thickness of BX276 Backing Plate is 0.276 in. (7 mm),
therefore the overall minimum thickness is 0.402 in. (10.2 mm)

D

Minimum thickness of BX277 Backing Plate is 0.354 in. (9 mm),
therefore the overall minimum thickness is 0.480 in. (12.2 mm)
0% Remaining Life

C

Outer
Brake
Pad

A

New pad thickness 1.181 in. (30 mm)
BX276/BX277: Refer to image below for measurement locations
BX275/BX283: Measure anywhere on the backing plate surface

B

New rotor thickness 1.77 in. (45 mm)
Minimum rotor thickness 1.46 in. (37 mm)

C

Minimum friction material thickness 0.125 in.
(3.2 mm) - approximately the thickness of a nickel

Brake
Disc

Not OK

b) A = 13mm
B = 15mm
–> |B – A| = 2mm
c) A = 12mm
B = 9mm
–> |B – A| = 3mm

OK

OK

D

A

E
F

B

D) Pad Surface Damage

C
A

BX276: .91 in. (23 mm)
BX277: .83 in. (21 mm)

D

BX276: .28 in. (7 mm)
BX277: .35 in. (9 mm)

B

1.18 in. (30 mm)

E

.13 in. (3.2 mm)

C

1.26 in. (32 mm)

F

BX276: .40 in. (10.2 mm)
BX277: .48 in. (12.2 mm)

P

B) Uneven Wear on Single Pad

P

B

Rotation

Disc Brake Pads

New
Friction
100% Life

Inner
Brake
Pad

Example:
a) A = 6mm
B = 15mm
–> |B – A| = 9mm

Inner
Brake
Pad

Outer
Brake
Pad

Brake
Disc

x

Pads are OK if A – B < 2mm
Example:
a) A = 19mm
B = 15mm
–> A – B = 4mm
Not OK
b) A = 13mm
B = 11.5mm
–> A – B = 1.5mm
OK

A

Boots & Seals

Bendix® Pad/Rotor Measuring Tool (K109114)

E) Tears and Cuts

F) Melting

J – Rotors
– Surface
Damage
J – Rotors
– Surface
Damage

I) Worn RotorsJ

45mm – as new

37mm – worn

Rotors

– Rotors – Surface
Damage
J) Surface Damage
Area F

Area H

Area G

Area J

No action is
needed for small
cracks spread
over the surface
Inner
Brake
Pad

Outer
Brake
Pad
Brake
Disc

Cracks reaching
either edge of the
rotor are not
acceptable for
either type of rotor

For standard Bendix® rotors, cracks running in a
radial direction–like spokes of a wheel–less than
0.06 in. (1.5 mm) and for Bendix® Splined Disc®
rotors, radial cracks less than 0.04 in.
(1.0 mm) deep or wide are acceptable
if they do not reach either edge (see
Area G). Cracks are only acceptable
if the length of the crack is less than
75% of dimension “f” (the width of
the rotor contact area).

Circumferential
grooves are
acceptable if
less than 0.06 in.
(1.5 mm) deep

Bendix® Pad/Rotor Measuring Tool (K109114)

BW7610 Rev 006 © 4/2025 Bendix Commercial Vehicle Systems LLC, a member of Knorr-Bremse • All Rights Reserved

In addition, follow the recommendations
of the vehicle manufacturer.
Note: Axles should have either all Bendix
splined discs (or all conventional) rotors.
A mirror or boroscope camera can be
used to assist with inspections. Inspect
for spongiosis and rotor cheek separation
in the cooling vanes. When addressing
splined disc rotors, look for tooth shearing
and damage.