Service Bulletin
ULX40 Axle Suspension Systems with PSI Tire
Inflation Systems Installed on GDLP Trailers
SAF-HOLLAND® has identified axle assemblies installed on ULX40
axle suspension systems that may have tire inflation spindle plugs
that are installed askew relative to the spindle bore.
These were installed on GDLP trailers with the following VIN:
list to be provided by GDLP.

January 2017

Figure 1
SERIAL NUMBER TAG LOCATED
NEAR CENTER OF AXLE TUBE

Model Identification
The location of the axle serial tag is found near the center of the
axle (Figure 1), and the suspension serial tag is located on the
front crossmember (Figure 2). The serial number is on the last
line of the sample tag shown (Figure 3).

Inspection procedure
In preparation for this inspection, consult XL-TA10006OM-en-US
for relevant safety instructions. MTIS maintenance manual
mm14P was also used for additional MTIS information.

Figure 2

The tools and supplies needed for the inspection and rework
are as follow.
TAG LOCATED ON FRONT
CROSS MEMBER

Required Tools:


7/16" wrench



5/8" socket



Dial depth indicator -supplied by SAF-HOLLAND



Torque wrench 0-55 in-lbs. and 0-28 ft-lbs.



PSI plug installation driver –supplied by SAF-HOLLAND



3-4 lbs. hammer



Bore polisher for 2.75" diameter



Slide hammer tool to remove spindle plug

Required Supplies:


Alcohol wipes



Replacement PSI spindle plugs (if needed)



Sealant (Loctite 620 or Permabond HH40)



Replacement hub cap gasket (Replace if damaged)



Spare hub cap bolts and washers (if any are lost)



Replacement wheel bearing grease

Figure 3

XL-MS20037SB-en-US Rev A · 2017-01-24 · Amendments and Errors Reserved · © SAF-HOLLAND, Inc., SAF-HOLLAND, HOLLAND, SAF,
and logos are trademarks of SAF-HOLLAND S.A., SAF-HOLLAND GmbH, and SAF-HOLLAND, Inc.

Service Bulletin
Following the steps below perform the inspection on each wheel
end assembly:
1.

Record VIN of trailer, suspension serial number, and each axle
serial number in the location provide on Table 1 Page 5.

2.

Turn the tire inflation system off using the shut-off valve at
the MTIS control box (Figure 4). so that the shut off valve
is in closed position when yellow handle is 90˚ with the fittings (Figure 5).

3.

Open drain valve by turning valve counter clockwise to
completely open (Figure 6).

4.

When air stops coming out the Drain Hole, the system is
Depressurized.

5.

Remove the hoses from the thru-tee. Then remove the thru-tee
and hubcap. Save bolts, washers, and gasket if possible.

6.

Cover the wheel end with a clean towel or plastic cover to
protect the bearings from contaminants.

7.

Wipe any grease from spindle ID including the PSI plug face
and end of spindle.

8.

Set gage (Figure 7) against spindle face:

Figure 4

SHUT OFF VALVE

DRAIN VALVE

Figure 5

a. “Steps” of gage base are flat to the spindle face.
b. Indicator face is easily visible, typically with gage face up
at 7 o’clock.
9.

Set the dial on indicator to “0” (Figure 7).

10. Grasping the edges of gage base, to maintain firm flatness
to the spindle face, rotate the gage 360˚, reading the
indicator needle.

Figure 6

11. The dial indicator reading from each wheel end is to be
recorded in the specific location provided on Table 1.
12. If the maximum variation detected is 0.030" or less the
installed plug is considered acceptable. Go to Step 35
13. If the maximum variation detected is greater than 0.030"
the installed plug will need to be removed and replaced.

DRAIN HOLE

14. Remove stator pipe from axle press plug.
15. Use a slide hammer fitted with the axle press plug removal
tool to remove the axle press plug. Use care not to score
the inside diameter of the spindle bore (Figure 8).

Figure 7

Use a bore polisher to remove all old
adhesive from the spindle bore before you
apply retaining compound to install the
axle press plug. Retaining compound must
contact a bare metal surface or it will not
harden. Damage to components can result.
16. Polish the spindle bore to remove all adhesive residue left
from the old spindle plug and any metal burrs or sharp
edges from the spindle bore surface (Figure 9).

XL-MS20037SB-en-US Rev A · 2017-01-24 · Amendments and Errors Reserved · © SAF-HOLLAND, Inc., SAF-HOLLAND, HOLLAND, SAF,
and logos are trademarks of SAF-HOLLAND S.A., SAF-HOLLAND GmbH, and SAF-HOLLAND, Inc.

2

Service Bulletin
17. If the axle spindle is equipped with cotter pin holes: Use
a round abrasive tool to remove all metal burrs and sharp
edges from the spindle bore side of the cotter pin holes.

Figure 8
AXLE PRESS PLUG REMOVER

18. Install new press plug onto PSI plug installation driver
(Figure 10).
19. Clean the exposed O-ring surface and outside diameter of the press
plug using a cleaning towelette or other alcohol cleaning agent.
20. Using the same towelette or cleaning agent, clean the
spindle bore of contaminants such as dust, grease and oil.
21. Apply the retaining compound (PERMABOND - PERMANENT
RETAINER HH040, OR LOCTITE 620) evenly to the outside
diameter of the press plug (see below). Press plug must be
installed within 10 minutes of applying the retaining compound to ensure compound hardens correctly (Figure 10).
Be sure to wear hand protection when
handling retaining compound.

SLIDE HAMMER

Figure 9

22. If installing a press plug with a thermal screw for THERMALERT™
System, install the screw at the 12 O’clock position.
BORE POLISHING

23. Insert the press plug by hand into the spindle bore until the
plug stops in the bore.
24. Insert the PSI plug installation driver supplied by SAF-HOLLAND.
25. Using a 4 Lb. brass or synthetic mallet, drive the press plug
into the spindle bore until the adapter bottoms out. The
installation driver sets the press plug depth.
26. Wipe off all retaining compound residue from the spindle
and press plug. Clean any additional compound off the tool.
27. Insert stator into spindle plug hand tight.
28. Using a 5/8" socket tighten stator approximately 2.5
additional turns or 23-28 ft-lbs. [31-38 N•m].
29. Recheck the variation of the press plug face skewness
starting at Step 7 above, recording the dial indicator reading just below the original reading on Table 1.
Caution must wait minimum 30 minutes
before pressurizing tire inflation system.

Figure 10

PRESS PLUG

30. To leak test the new press plug, inset the thru-tee into the stator
and hold it in place. Turn the system ON by reversing Steps 2 and 3.
31. Fully pressurize the tire inflation system by connecting the
trailer to a pressure source that can deliver 20 psi [137.9
kPa] above the control box setting, typically 120-130 psi
[827-896 kPa] to the trailer glad hands. Allow the air pressure source sufficient time to pressurize the system, which
may take up to 10 minutes.

3

APPLY RETAINING
COMPOUND TO
THIS SURFACE

XL-MS20037SB-en-US Rev A · 2017-01-24 · Amendments and Errors Reserved · © SAF-HOLLAND, Inc., SAF-HOLLAND, HOLLAND, SAF,
and logos are trademarks of SAF-HOLLAND S.A., SAF-HOLLAND GmbH, and SAF-HOLLAND, Inc.

Service Bulletin
32. Ensure to hold the tee straight into the axle. Spray the axle
press plug area with a non-corrosive leak detecting solution
to check for leaks.

Figure 11

33. When a complete seal is obtained re assembly of wheel end
can be started.
34. Turn OFF Air and drain per Steps 2, 3 and 4.
35. Remove rags or cover protecting bearings.

DUAL WHEELS

36. Re-install hub cap, gasket, and 6 bolts and washers. Pay
attention to orientation of hose connections. Replace any
lost grease (Figure 11).
37. Tighten 6 bolts in a criss-cross pattern to 12-16 ft-lbs.
[16.3-21.7 N•m].
38. Hand-tighten the thru-tee assembly. Tighten the tee with a
torque wrench set at 45 in-lbs. [5 N•m].
39. Check alignment of the tee air fittings to the tire valve stems
(Figure 11). They should point toward the tire valve stems.
If not aligned, retighten the tee with a torque wrench set to
55 in-lbs. [6 N•m] and tighten until aligned. DO NOT exceed
55 in-lbs. [6 N•m].

SINGLE WHEELS

Figure 12

HUB CAP
RELIEF
VALVE

40. Re-attach the air hose fittings to the Thru-Tee hand tight.
Then use a 7/16" wrench to tighten the connections an
additional half-turn.
CHECK THE WHEEL END FOR AIR LEAKS

NON
CORROSIVE
LEAK
DETECTION
SOLUTION

41. Close drain petcock on control box by turning clockwise all
the way by reversing Step 3.
42. Turn on supply air at MTIS control box and charge system.
43. The tire inflation system must be fully pressurized before
proceeding. This may take up to 10 minutes, since the
axles, tires and possibly the brake system will have to be
pressurized. A shop air source will charge the system more
quickly than a tractor compressor.
44. Fully pressurize the tire inflation system by connecting the
trailer to a pressure source that can deliver 20 psi [137.9
kPa] above the control box setting, typically 120-130 psi
[827-896 kPa] to the trailer glad hands. Allow the air pressure source sufficient time to pressurize the system, which
may take up to 10 minutes.

HOSE TO
THRU TEE
CONNECTION

Figure 13

45. Test the tire inflation system for air leaks. Spray a non-corrosive
leak detection solution on the fittings and hose connections to
check for leaks (Figure 12).
46. Look for bubbling and listen for audible leaks.
47. Tighten or replace fittings that leak.
48. Following completion of the above steps for all four wheel
ends, using a highly visible colored marker or paint marker,
a check mark needs to be made on or near the white
adhesive suspension serial tag, located as shown in
Figure 13 of the bulletin.
XL-MS20037SB-en-US Rev A · 2017-01-24 · Amendments and Errors Reserved · © SAF-HOLLAND, Inc., SAF-HOLLAND, HOLLAND, SAF,
and logos are trademarks of SAF-HOLLAND S.A., SAF-HOLLAND GmbH, and SAF-HOLLAND, Inc.

4

Service Bulletin
Table 1

GREAT DANE TRAILER
VIN #

5

SAF-HOLLAND
SUSPENSION
SERIAL #

DIAL INDICATOR READING - HIGHEST VALUE
FRONT AXLE
SERIAL #

REAR AXLE
SERIAL #

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

5116-

CURB
FRONT

CURB
REAR

ROAD
FRONT

ROAD
REAR

XL-MS20037SB-en-US Rev A · 2017-01-24 · Amendments and Errors Reserved · © SAF-HOLLAND, Inc., SAF-HOLLAND, HOLLAND, SAF,
and logos are trademarks of SAF-HOLLAND S.A., SAF-HOLLAND GmbH, and SAF-HOLLAND, Inc.

SAF-HOLLAND Original Parts are the same quality components used
in the original component assembly.
SAF-HOLLAND Original Parts are tested and designed to provide
maximum performance and durability. Will-fits, look-alikes or, worse
yet, counterfeit parts will only limit the performance potential and
could possibly void SAF-HOLLAND’s warranty. Always be sure to spec
SAF-HOLLAND Original Parts when servicing your
SAF-HOLLAND product.

SAF-HOLLAND USA

·

888.396.6501

·

Fax 800.356.3929

www.safholland.us

SAF-HOLLAND CANADA
WESTERN CANADA

·
·

519.537.3494
604.574.7491

·
·

Fax 800.565.7753
Fax 604.574.0244

www.safholland.ca

SAF-HOLLAND MEXICO
www.safholland.com.mx

[email protected]

SAF-HOLLAND INC.
1950 Industrial Blvd., Muskegon, MI 49442
www.safholland.com

· 52.55.5362.8743 · Fax

52.55.5362.8743

XL-MS20037SB-en-US Rev A · 2017-01-24 · Amendments and Errors Reserved · © SAF-HOLLAND, Inc., SAF-HOLLAND, HOLLAND, SAF, and logos are trademarks of SAF-HOLLAND S.A., SAF-HOLLAND GmbH, and SAF-HOLLAND, Inc.

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