Accuride Gunite Series Reference guide

Gunite®Automatic Slack Adjusters
Gunite®Automatic Slack Adjuster
Installation Procedures
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STEEL & ALUMINUM WHEELS | DRUMS | HUBS | ROTORS | SLACK ADJUSTERS
Assembled in the USA

Gunite®Automatic Slack Adjusters
WARNING
As with all products, close attention should be given to all instructions incorporated in these instructions, in particular, the notes and
warnings which are highlighted.
Failure to strictly adhere to these notes and warnings may cause the unit to not perform as designed and result in a weak or “NO
BRAKE” condition, which could cause extensive property damage, bodily injury or death.
1. If the axle is equipped with spring brake chambers, manually
cage the spring brakes following the manufacturer’s
recommended procedures.
2. Check the operating condition of the foundation brakes, including
drums, shoe and linings, cams, bushings, rollers, etc. Replace or
repair as necessary.
Preparation for Installation
NOTE:
When caging the spring brakes, always be sure to block the
vehicle wheels to prevent unwanted movement.
1. Apply anti-seize compound to the end of the air chamber push
rod. Install the 1-1/4" collar nut on the air chamber push rod.
Thread the 3/4" hex nut onto the push rod.
2. Apply anti-seize to the camshaft splines and install the slack
adjuster onto the camshaft using the original mounting hardware.
3. Using the wrench or socket, rotate the hex extension to align the
1-1/4" collar nut with the threaded part of the clevis. See Figure
2.
4. Before threading the 1-1/4" collar nut onto the clevis check to
make sure that the push rod is fully engaged in the 3/4" hex
nut. If the push rod is not fully engaged, a new push rod must
be installed. Refer to the section on cutting a push rod to length
in the service manual. The push rod may extend 1/16" past the
clevis opening. If the push rod extends more than 1/16" mark the
push rod, remove the clevis and cut the push rod to the proper
length.
An extended clevis may be used in trailer applications instead of
replacing the push rod. However you must still have full thread
engagement on the hex nut. If you have less than full thread
engagement, a new push rod must be installed. Do not use an
extended clevis on tractor applications, the extended clevis may
interfere with the face of the air chamber.
Installation of the Gunite Collar Lock Clevis and Extended Collar Lock Clevis
NOTE:
On axles equipped with spring brake chambers, be
sure the chambers are fully caged before cutting the
push rod. If the spring brakes are not fully caged, the
push rod can be cut too short.
3. Remove the existing clevis and slack adjuster. Do not discard
the existing mounting hardware. Do not remove the clevis jam
nut.
4. Refer to Figure 1 and determine if your Gunite slack adjusters
are equipped with the threaded clevis or the collar lock clevis
(extended or standard length). Refer to the correct installation
procedure for the style of clevis used on your Gunite slack
adjusters.
- 3/4"
Hex Nut
- 1-1/4"
Collar Nut
Standard
Threaded Clevis
Standard length clevises can be used for
either truck or trailer applications.
Extended clevises should be used
for trailer applications only.
Standard Collar
Lock Clevis
Extended
Threaded Clevis
Extended Collar
Lock Clevis
Collar
Lock
Clevis
Collar Lock
Nut and Clevis
Figure 1 - Clevis Types
Figure 2 - Align the 1-1/4” collar nut with the threaded
part of the clevis.

Gunite®Automatic Slack Adjusters
1. Manually uncage the spring brakes.
2. Build-up vehicle air pressure. If the axle in question has
parking brakes, be sure they’re released. Using template,
recheck for proper clevis setting. If incorrect, readjust per
instructions under installation procedures.
3. Fully apply the brakes and allow the air chamber to travel
its maximum stroke. Clearance must exist between the slack
and all adjacent chassis components such as axle housing,
suspension brackets, etc. Release the brakes.
4. After completing this procedure, follow the instructions for
the proper brake adjustment after installation on page 4.
Installation Check
5. Thread the 1-1/4" collar nut
onto the clevis and install
the template over the large
and small pins as shown in
Figure 3.
6. Align the slack by
adjusting the 3/4" hex
nut on the push rod until
the proper centering hole
aligns with the center hole
on the camshaft.
7. Once the slack is properly aligned, tighten the 1-1/4" collar nut
to the clevis using 40 to 50 ft. lbs. of torque.
8. After tightening the 1-1/4" collar lock nut, tighten the 15/16"
jam nut against the collar lock nut using 40 to 50 ft. lbs.
torque.
9. Next follow the instructions in the installation check section
below.
NOTE:
Failure to tighten the jam nut will allow the air chamber
push rod to rotate in the clevis and change the installed
position of the slack, preventing proper automatic adjuster
function.
1. Apply anti-seize compound to the air chamber push rod.
Install the new clevis on the air chamber push rod in the
same location as the clevis which was removed. Do not
tighten the jam nut at this
time.
2. Insert the clevis pins into
the threaded clevis. Install
the template over the
small and large pins as
shown in Figure 4. Align
the slack by adjusting
the clevis in or out on the
push rod until the hole at
the bottom of the template
aligns with the center hole
on the camshaft.
3. If the push rod threads
protrude through the clevis opening more than 1/16",
remove the clevis and cut the push rod to length. The push
rod must not be more than 1/8" short of being flush with
the clevis opening. Follow instruction in the service manual
for cutting a push rod to length.
4. If the push rod fails to come within 1/8" of full engagement
with the clevis opening, install a long push rod and cut to
length. On trailer applications, an extended clevis can be used
instead of replacing the push rod. However, you must have at
least 1/2" of thread engagement inside the clevis. If you have
less than 1/2" thread engagement, a new push rod must be
installed.
5. Tighten the jam nut against the clevis housing using 40 to 50
ft. lbs. of torque. Failure to tighten the jam nut now will allow
the clevis to rotate freely and change the position of the clevis
resulting in improper installation.
6. Apply anti-seize to the camshaft and install the slack using
original mounting hardware. Using a wrench or socket,
rotate the hex extension until the holes in the slack housing
align properly with the holes in the clevis. Hold the link (rod
with small 1/4” hole) down while rotating the hex extension
clockwise. Failure to do so can cause the link to disengage
from the drive.
7. Once properly aligned, insert both the large and small clevis
pins and insert the cotter pins.
8. Next follow the instructions in the installation check section
below.
NOTE:
On axles equipped with spring brake chambers, be sure the
chambers are fully caged before cutting the push rod. If the
spring brakes are not fully caged, the push rod can be cut too
short.
NOTE:
Failure to tighten the jam nut will allow the air chamber
push rod to rotate in the clevis and change the installed
position of the slack, preventing proper automatic adjuster
function.
Installation of the Gunite Threaded Clevis and Extended Threaded Clevis
Figure 3 -
Gage Location
Figure 4 - Gage Location

Gunite®Automatic Slack Adjusters
Gunite®Automatic Slack Adjuster
Installation Procedures
Adjust the Brakes as Follows:
1. Rotate the hex extension clockwise until the brake linings
contact the brake drum. Back off the slack by rotating the
hex counterclockwise 1/2 turn.
2. Backing off the slack will require more than 25 to 30 ft. lb.
of torque. When backing off the slack, a ratcheting sound
will be heard.
3. Using a ruler, measure the distance from the face of the air
chamber to the center of the large pin in the clevis. See A
in Figure 5. Make an 90 psi brake application and allow the
air chamber push rod to travel its maximum stroke. Measure
to the center of the large pin in the clevis. See B in Figure 5.
The difference between A and B measurement is the push
rod stroke. Check the following chart, Figure 6, for proper
maximum stroke after the adjustment of the brakes.
Brake Adjustment After Installation
Measuring the Free Stroke:
1. Free stroke is the amount of movement of the slack arm
required to move the brake shoes against the drum. With
brakes released, measure from the face of the chamber to the
center of the clevis pin. See Figure 7. Apply pressure using a
lever to activate the slack adjuster until the brake shoes make
contact with the drum. The difference between the released
and the applied measurements is the free stroke. The free
stroke should be between 3/8" - 5/8".
If the free stroke is good, but the applied stroke is too long,
there is a problem with the foundation brake. Check the
foundation brake for missing or worn components, cracked
brake drums, or improper lining to drum contact.
If the free stroke is greater than the recommended distance
(3/8" - 5/8"), a function test of the slack adjuster should be
performed.
If the free stroke is less than 3/8", a dragging break can occur.
Check to see that the manual adjustment procedure was
followed correctly. Manually readjust the brake following the
“Brake Adjustment After Installation” procedure on this page.
Figure 6
Figure 5 –
Measuring Maximum Stroke
Figure 7 –
Free Stroke
Lubrication
The Gunite slack adjusters are factory-lubricated and extensively sealed to protect against dirt, water, salt and other corrosive elements.
However, it is recommended periodic lubrication take place every 6 months or 50,000 miles ensuring the Tru-Seal® link boot, O-rings
and internal components maintain proper lubrication; this should be performed using an NLGI 1 or 2 grade grease that has a working
range of -40 - 250 degrees F. A grease containing Molybdenum Disulfide should not be used as it will likely have a negative impact on
the function of key friction components and reduce the operational efficiency of the automatic slack adjuster.
For additional service information refer to Gunite Automatic Slack Adjuster Service Manual (WE3.000) or visit our website at
AccurideWheelEndSolutions.com.
Your only single source for industry-leading wheel end solutions.
STEEL & ALUMINUM WHEELS | DRUMS | HUBS | ROTORS | SLACK ADJUSTERS
For more information: [phone] / [phone] | accuridewheelendsolutions.com
Gunite | 302 Peoples Avenue | Rockford, IL 61104–7092
WE4.005 0214 Replaces SD-04003 1299 ©2014 Accuride Corporation
Type Outside
Diameter Rated Stroke
Maximum
Legal Stroke
Limit
95-1/4 1.75 1-3/8
12 5-11/16 1.75 1-3/8
16 6-3/8 2.25 1-3/4
20 6-25/32 2.25 1-3/4
24 7-7/32 2.25 1-3/4
30 8-3/32 2.50 2
36* 93.00 2-1/4
* Note: If type 36 chamber is used, slack length should be less than 6".
“STANDARD” CLAMP TYPE BRAKE CHAMBER DATA
Type Outside
Diameter Rated Stroke
Maximum
Legal Stroke
Limit
16 6-3/8 2.50 2
20 6-25/32 2.50 2
24 7-7/32 2.50 2
24* 7-7/32 3.00 2-1/2
30* 8-3/32 3.00 2-1/2
* Note: Identified by square air port bosses.
“LONG-STROKE” CLAMP TYPE BRAKE CHAMBER DATA