ASTM D7038-23

Standard Test Method for Evaluation of Moisture Corrosion Resistance of Automotive Gear Lubricants

SIGNIFICANCE AND USE
5.1 This test simulates a type of severe field service in which corrosion-promoting moisture in the form of condensed water vapor accumulates in the axle assembly. This may happen as a result of volume expansion and contraction of the axle lubricant and the accompanied breathing in of moisture-laden air through the axle vent. The test screens lubricants for their ability to prevent the expected corrosion.  
5.2 The L-33-1 test procedure is used or referred to in the following documents: ASTM Publication STP-512A,6 SAE J308, SAE J2360, and U.S. Military Specification MIL-PRF-2105E.
SCOPE
1.1 This test method covers a test procedure for evaluating the rust and corrosion inhibiting properties of a gear lubricant while subjected to water contamination and elevated temperature in a bench-mounted hypoid differential housing assembly.2 This test method is commonly referred to as the L-33-1 test.  
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.2.1 Exceptions—(1) where there is no direct SI equivalent such as screw threads and national pipe threads/diameters, and (2) the values stated in SI units are to be regarded as standard for the definitions in 12.2, and for SI units where there are no direct inch-pounds equivalent units.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 75.100 - Lubricants, industrial oils and related products
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.B0 - Automotive Lubricants

Relations

• Replaces: ASTM D7038-22a - Standard Test Method for Evaluation of Moisture Corrosion Resistance of Automotive Gear Lubricants
• Effective Date: 01-Nov-2023
• Referred By: ASTM D7450-19 - Standard Specification for Performance of Rear Axle Gear Lubricants Intended for API Category GL-5 Service
• Effective Date: 01-Nov-2023

Overview

ASTM D7038-23 is the international standard test method for evaluating the moisture corrosion resistance of automotive gear lubricants. Developed and published by ASTM International, this standard outlines a laboratory procedure-commonly known as the L-33-1 test-for assessing the ability of gear oils to inhibit rust and corrosion under simulated severe field service conditions. These conditions replicate scenarios where moisture-laden air is drawn into axle assemblies and condenses, potentially promoting corrosion within the automotive drivetrain.

This rigorous test is essential for lubricant manufacturers, automotive engineers, and quality assurance professionals to validate the durability and protection offered by gear lubricants, especially in environments susceptible to water and humidity exposure.

Key Topics

• Purpose and Scope:

  • Simulates exposure of automotive hypoid differentials to condensed water vapor and elevated temperatures.
  • Measures the corrosion-inhibiting performance of lubricants under controlled laboratory conditions.
  • Provides a standardized method to compare gear lubricants’ resistance to rust and corrosion.

• Test Procedure Highlights:

  • Utilizes a bench-mounted hypoid differential housing assembly.
  • Lubricant, along with a controlled amount of water, is subjected to heating and extended storage phases.
  • Post-test, inspection focuses on the degree and distribution of corrosion, rust, stains, or other deposits.

• Evaluation and Reporting:

  • Ratings are based on specific surfaces and components as per ASTM Distress Rating Manual.
  • Test results are reported using standardized forms for consistency and regulatory compliance.
  • Calibration and reference oils are used to assure consistency and repeatability across laboratories.

• Importance in Industry:

  • Helps automotive OEMs and lubricant formulators meet industry and military specifications (such as SAE J2360 and MIL-PRF-2105E).
  • Supports qualification for gear oils intended for severe service and high-demand environments.

Applications

ASTM D7038-23 is widely applied across the automotive and lubricant industries as a key method for:

• Product Development and Quality Control:

  • Lubricant formulators use the L-33-1 test to verify additive technologies and improvements in moisture corrosion resistance before product launch.
  • Manufacturers use this test to monitor batch-to-batch product consistency and compliance with industry requirements.

• Specification and Qualification:

  • Required by organizations and regulatory bodies for ensuring lubricants meet or exceed minimum corrosion protection thresholds.
  • Test outcomes are referenced in critical industry documents, such as SAE J308 (Axle and Manual Transmission Lubricants) and U.S. Military Specification MIL-PRF-2105E.

• Performance Claims and Certification:

  • Results from ASTM D7038-23 support performance claims regarding gear oil longevity and equipment protection.
  • Serves as a basis for lubricant approval and certification programs, facilitating market access.

Related Standards

For comprehensive gear lubricant evaluation, consider these related documents:

• ASTM D235: Specification for Mineral Spirits (used as cleaning solvent in the test method).
• SAE J308: Information Report on Axle and Manual Transmission Lubricants.
• SAE J2360: Lubricating Oil, Gear Multipurpose (for military use and performance requirements).
• MIL-PRF-2105E: U.S. Military Specification for General Multipurpose Gear Oils.
• ASTM STP-512A: Compilation of laboratory performance tests for automotive gear lubricants.
• ASTM Distress Rating Manual 21: For standardized rating of corrosion and distress on tested parts.

Implementing ASTM D7038-23 helps organizations ensure their gear lubricants provide robust corrosion inhibition in real-world conditions, meeting both industry and regulatory expectations for automotive performance and longevity.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7038 − 23
Standard Test Method for
Evaluation of Moisture Corrosion Resistance of Automotive
Gear Lubricants
This standard is issued under the fixed designation D7038; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Portions of this test method are written for use by laboratories that make use of ASTM Test
Monitoring Center (TMC) services (see Annex A1 – Annex A4).
The TMC provides reference oils, and engineering and statistical services to laboratories that desire
to produce test results that are statistically similar to those produced by laboratories previously
calibrated by the TMC.
In general, the Test Purchaser decides if a calibrated test stand is to be used. Organizations such as
the American Chemistry Council require that a laboratory use the TMC services as part of their test
registration process. In addition, the American Petroleum Institute and the Gear Lubricant Review
Committee of the Lubricant Review Institute (SAE International) require that a laboratory use the
TMC services in seeking qualification of oils against their specifications.
The advantage of using the TMC services to calibrate test stands is that the test laboratory (and
hence the Test Purchaser) has an assurance that the test stand was operating at the proper level of test
severity. It should also be borne in mind that results obtained in a non calibrated test stand may not
be the same as those obtained in a test stand participating in the ASTM TMC services process.
Laboratories that choose not to use the TMC services may simply disregard these portions.
ASTM International policy is to encourage the development of test procedures based on generic
equipment. It is recognized that there are occasions where critical/sole-source equipment has been
approved by the technical committee (surveillance panel/task force) and is required by the test
procedure. The technical committee that oversees the test procedure is encouraged to clearly identify
if the part is considered critical in the test procedure. If a part is deemed to be critical, ASTM
encourages alternative suppliers to be given the opportunity for consideration of supplying the critical
part/component providing they meet the approval process set forth by the technical committee.
An alternative supplier can start the process by initiating contact with the technical committee
(current chairs shown on ASTM TMC website). The supplier should advise on the details of the part
that is intended to be supplied. The technical committee will review the request and determine
feasibility of an alternative supplier for the requested replacement critical part. In the event that a
replacement critical part has been identified and proven equivalent, the sole-source supplier footnote
shall be removed from the test procedure.
1. Scope* ture in a bench-mounted hypoid differential housing assembly.
This test method is commonly referred to as the L-33-1 test.
1.1 This test method covers a test procedure for evaluating
the rust and corrosion inhibiting properties of a gear lubricant 1.2 The values stated in inch-pound units are to be regarded
while subjected to water contamination and elevated tempera- as standard. The values given in parentheses are mathematical
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Until the next revision of this test method, the ASTM Test Monitoring Center
Subcommittee D02.B0 on Automotive Lubricants. (TMC) will update changes in this test method by means of Information Letters.
Current edition approved Nov. 1, 2023. Published November 2023. Originally This edition includes all Information Letters through 23-1. Information Letters may
approved in 2004. Last previous edition approved in 2022 as D7038 – 22a. DOI: be obtained from the ASTM Test Monitoring Center, 203 Armstrong Drive,
10.1520/D7038-23. Freeport, PA 16229, Attention: Director.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7038 − 23
conversions to SI units that are provided for information only 3.1.4 stain, n—a surface modification that is attributable to
and are not considered standard. discoloration only.
1.2.1 Exceptions—(1) where there is no direct SI equivalent
4. Summary of Test Method
such as screw threads and national pipe threads/diameters, and
(2) the values stated in SI units are to be regarded as standard
4.1 This procedure uses a new hypoid differential assembly
for the definitions in 12.2, and for SI units where there are no
as the primary test unit. The differential assembly is installed
direct inch-pounds equivalent units.
on a motoring rig and charged with test lubricant and a small
amount of water. The test unit is then sealed and driven until
1.3 This standard does not purport to address all of the
the lubricant temperature has increased to 180 °F (82.2 °C).
safety concerns, if any, associated with its use. It is the
The motoring phase is continued for 4 h and the test unit is then
responsibility of the user of this standard to establish appro-
removed from the motoring rig and placed in a storage box for
priate safety, health, and environmental practices and deter-
162 h with the lubricant temperature controlled at 125 °F
mine the applicability of regulatory limitations prior to use.
(51.7 °C). The test is completed at that time and the differential
1.4 This international standard was developed in accor-
assembly is drained, disassembled, and inspected for rust,
dance with internationally recognized principles on standard-
stain, and other deposits.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
5. Significance and Use
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 5.1 This test simulates a type of severe field service in
which corrosion-promoting moisture in the form of condensed
2. Referenced Documents
water vapor accumulates in the axle assembly. This may
happen as a result of volume expansion and contraction of the
2.1 ASTM Standards:
axle lubricant and the accompanied breathing in of moisture-
D235 Specification for Mineral Spirits (Petroleum Spirits)
(Hydrocarbon Dry Cleaning Solvent) laden air through the axle vent. The test screens lubricants for
their ability to prevent the expected corrosion.
E29 Practice for Using Significant Digits in Test Data to
Determine Conformance with Specifications
5.2 The L-33-1 test procedure is used or referred to in the
2.2 Society of Automotive Engineers Standards:
following documents: ASTM Publication STP-512A, SAE
J308 Information Report on Axle and Manual Transmission
J308, SAE J2360, and U.S. Military Specification MIL-PRF-
Lubricants
2105E.
J2360 Lubricating Oil, Gear Multipurpose (Metric) Military
Use
6. Apparatus
2.3 U.S. Military Specifications:
6.1 Laboratory Ambient Conditions:
MIL-PRF-2105E Lubricating Oil, Gear, General Multipur-
6.1.1 Test Operating Area—The ambient laboratory atmo-
pose
sphere shall be free of dirt, dust, and other contaminants as
MIL-P-3420F NOX-RUST Paper
required by good laboratory standards.
6.1.2 Parts Cleaning and Abrasive Blasting (6.2.8) Areas—
3. Terminology
Provide adequate ventilation in areas where solvents (7.2) are
3.1 Definitions of Terms Specific to This Standard:
used. (Warning—Combustible, vapor harmful.)
3.1.1 corrosion, n—an alteration of a finished metal surface
6.1.3 Build-up Area—It is recommended that the atmo-
by discoloration, accompanied by roughening not attributable
sphere in the test unit build-up area be filtered and maintained
to mechanical action.
at uniform temperature and low humidity to prevent accumu-
3.1.2 downtime, n—an interruption of power to the test unit
lation of dirt or rust on test parts. Otherwise it shall conform to
for a period greater than ten seconds. requirements of 6.1.1.
6.1.4 Parts Rating Area—Conduct the rating of all test parts
3.1.3 rust, n—a special case of corrosion, which always
under conditions as defined in ASTM Distress Rating Manual
deteriorates or alters the original surface condition.
21.
3.1.3.1 Discussion—Rust always has color (usually, but not
limited to red, yellow, brown, black) and one of the following
6.2 Test Unit—This procedure uses a hypoid differential
descriptive characteristics: (1) depth; the rusted surface is built
assembly (without axle tubes). See the critical parts list under
up relative to that of adjacent areas. (2) texture; the surface
the L-33-1 Information Letter section of the Test Monitoring
may appear to be etched, scaly or otherwise visibly different
Center website, www.astmtmc.org, for hardware approved for
than adjacent areas.
test use.
6.2.1 Mount the differential housing assembly on the mo-
toring rig so that the housing cover attaching face is in the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. ASTM Publication STP-512A, Laboratory Performance Tests for Automotive
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale, Gear Lubricants Intended for API GL-5 Service, ASTM International, West
PA 15096, http://www.sae.org. Conshohocken, PA.
5 7
Available from the Defense Printing Service Office, 700 Robbins Ave., Bldg. For stock #TMCMNL21, visit the ASTM website, www.astm.org, or contact
4D, Philadelphia, PA 19111-5094. ASTM Customer Service at [e-mail].
D7038 − 23
vertical plane and at a height that allows the temperature able cooling capability. Fig. A5.3 shows an example of the
sensing probe to be located in the bottom of the housing. location of the heat lamp pair and the cooling fan. Fig. A5.4
Elements of the motoring rig design are shown in Figs. shows the location of the temperature sensor in the differential
A5.1-A5.4. housing.
6.2.2 Drive System—The drive system design is not pre-
6.2.7 Storage Box and Temperature Control System, Storage
cisely specified; however, the following equipment or its
Phase—During the storage phase of the test, a double-walled
equivalent have been found to be suitable to turn the drive
aluminum or stainless steel box covers the differential housing
pinion at the specified 2500 r ⁄min 6 25 r ⁄min. (Warning—
assembly. An RTD or thermocouple (E, J, or K type) in
Rotating test stand equipment presents a physical hazard, use
conjunction with the controller regulates heat input from four
safety guards.)
strip heaters giving a total output of 1700 Btu ⁄h (500 W). A
6.2.2.1 Electric Motor, approximately 2.0 hp (1.5 kW),
small electric motor turns a fabricated impeller at 1700 r ⁄min
enclosed, 3600 r ⁄min, 0.87 in. (22.2 mm) diameter shaft.
6 100 r ⁄min to provide air circulation within the box. Dayton
6.2.2.2 Slide Motor Base, Dyn-Adjust No. 20-C.
part number 3M562 available from Grainger has been found
10,9
6.2.2.3 Dodge Taper Lock Pulleys, No. 40L100 (Driven)
suitable for this purpose. Control the bulk oil temperature at
and No. 28L100 (Drive).
125 °F 6 1 °F (52 °C 6 0.6 °C). Fig. A5.5 shows details of the
6.2.2.4 Dodge Timing Belt, No. 480L100.
impeller. Fig. A5.6 shows construction and electrical details of
6.2.2.5 Additional components such as shafts, couplings,
this box.
and bearing blocks are also necessary to connect the above
NOTE 1—Insulation on the outside surface of the box only may be
components to drive the carrier pinion, but are left to the option
necessary to maintain test temperature specifications.
of the testing laboratory.
6.2.8 Abrasive Blasting—Blast the entire differential case,
6.2.3 Vapor Pressure Control System—Control the internal
ring, pinion, side gears, differential pinion gears (spider gears),
vapor pressure of the unit during the warm-up portion of the
all four thrust washers and the inside surface of the differential
motoring phase with a specified water column pressure relief
housing cover plate with 80 grit aluminum oxide so as to
system set for 1.0 psi 6 0.1 psi (7 kPa 6 0.7 kPa) connected to
remove pre-existing corrosion and produce a uniform surface.
the housing cover with an appropriately sized National Pipe
Do not abrasive blast the bearings, bearing cups and differen-
Threads (NPT) stainless steel 90° street ell and a stainless steel
tial shaft (cross shaft pin). (Warning—Provide adequate safety
full port valve. The system shall contain an oil trap and return
equipment for abrasive blasting operations.)
vessel to return test oil to the unit in case of foaming, and a
6.2.9 The following specifies the abrasive blasting equip-
water trap and return vessel to prevent column water from
ment and material:
moving back to test unit. The example set up in Fig. A5.1 has
been shown to be acceptable. 6.2.9.1 Abrasive Blasting Cabinet—Grainger Econo-Line
10,9
6.2.4 Housing Cover Gasket—Replace the factory-supplied 36 in. by 24 in., Grainger Item No. 3Z850.
8,9
gasket with a single TFE fluorocarbon gasket for every test. (1) Use solely for cleaning L-33-1 test units.
6.2.5 Housing Axle Tube Opening Seals—Since the differ- (2) Measure air pressure for the blasting gun at the regu-
ential is tested without axle shafts or axle tubes, use a stainless
lator just prior to entering the cabinet enclosure. Set the
steel plumbing test plug for a 2.9 in. to 3.1 in. (74 mm to regulator to maintain 80 psig 6 2 psig (552 kPa 6 14 kPa)
79 mm) pipe diameter to seal the housing openings. McMas-
while flowing abrasive material.
11,9
terCarr p/n 2908K28 or 2908K29 with the outer washer and
6.2.9.2 Dust Collector—Grainger Econo-Line 1000 ft /min,
10,9
seal ring cut to 2.9 in. to 3.1 in. (74 mm to 79 mm) has been
Grainger Item No. 3JR93.
found acceptable for this purpose. Install a pair of seals in the
6.2.9.3 Blasting Gun Setup:
axle housing openings before installing carrier/case into the
(1) Grainger Econo-Line 12 ft /min Gun Assembly,
10,9
axle housing.
Grainger Item No. 3JT01.
6.2.6 Temperature Control System, Motoring Phase— 1
(2) Grainger Econo-Line tungsten carbide Nozzle Tip ⁄4 in.
10,9
During the motoring phase, the bulk oil temperature is sensed
I.D. Grainger Item No. 3JT08. Take care to install this
by a resistance temperature device (RTD) or thermocouple (E,
nozzle with the smaller opening facing out. The nozzle’s shape
J, or K type). The controller switches on a pair of 250 W lamps
makes it possible for it to be installed incorrectly. Change the
or cooling fan, or both, that are directed toward the differential
nozzle after fifteen L-33-1 units are blasted.
as needed to control bulk oil temperature at 180 °F 6 1 °F
(3) Grainger Econo-Line Air Jet 12 ft /min, Grainger Item
10,9
(82 °C 6 0.6 °C). A household-type electric fan having 12.0 in.
No. 3JT04.
(310 mm) diameter blades has been shown to provide accept-
6.2.9.4 Abrasive Blasting Material—Alodur Fused Brown
11,9 12,9
Aluminum Oxide, 80 grit—ANSI Table 3 Grade.
Change the entire cabinet supply of abrasive blasting material
The sole source of supply of the apparatus known to the committee at this time
is AP Services Inc., 18001 Sheldon Road, Middleburg Heights, OH 44130. Request
ASTM L-33-1 Die.
If you are aware of alternative suppliers, please provide this information to
ASTM International Headquarters. Your comments will receive careful consider- The sole source of supply of the apparatus known to the committee at this time
ation at a meeting of the responsible technical committee, which you may attend. is Grainger Inc., 120 Beta Drive, Pittsburgh PA 15238.
11 12
The sole source of supply for this material known to the committee at this time The sole source of supply of the apparatus known to the committee at this time
is Imerys Fused Materials Niagara Falls, Inc., 2000 College Avenue, M.P.O. Box is the American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New
1438, Niagara Falls, NY 14302, USA. York, NY 10036.
D7038 − 23
after 15 L-33-1 units are blasted. (Warning—Abrasive blast- individual components. Remove all grease and oil used during
ing presents a physical hazard; consult and follow equipment manufacturer’s assembly from bearings and wipe clean lip
manufacturer’s precautions.) seals with a dry cloth.
9.2.1.4 Functional Surface and Cover Plate Preparation—
7. Reagents and Materials
Abrasive blast the entire differential case, ring, pinion, side
gears, differential pinion gears (spider gears), all four thrust
7.1 Specified Test Water—Fisher Scientific deionized ultra
13,9
washers and the inside surface of the housing cover plate by
filtered water, Part No. W2-4 or W2-20.
uniformly abrasive blasting with 80 grit aluminum oxide. Do
7.2 Solvent—Use only mineral spirits meeting the require-
not abrasive blast the bearings, bearing cups and differential
ments of Specification D235, Type II, Class C for Aromatic
shaft (cross shaft pin). Do not touch any cleaned surface with
Content 0 % to 2 % vol, Flash Point (142 °F ⁄61 °C, min) and
bare hands as moisture can cause rusting.
Color (not darker than +25 on Saybolt Scale or 25 on Pt-Co
(1) After abrasive blasting and pre-test inspection (see
Scale). (Warning—Combustible. Health hazard.) Obtain a
9.2.1.5), pressure wash abrasive blasted parts, all four bearings,
Certificate of Analysis for each batch of solvent from the
and bearing cups with solvent and a round plastic bristle brush
supplier.
(pressure not to exceed 30 psi (207 kPa) (see 6.1.2). After
14,9
7.3 Rust Prevention Oil—Mobil Arma 245. (Warning—
pressure washing, rinse with solvent and dry with filtered
Combustible mixture. Harmful or fatal if swallowed.)
compressed air or nitrogen (pressure not to exceed 30 psi
(207 kPa) (see 7.2). A Wilkerson filter, model M18-02-
7.4 Build-up Lubricant—Use test oil for test unit build-up.
15,9
CH00 is required to filter the compressed air or nitrogen. A
15,9
8. Test Oil Wilkerson model MTP-96-64617 is the required replace-
ment element for the filter assembly. Do not use wire brushes
8.1 Use 1.0 gal (3.7 L) of fluid for each test. The housing
or abrasive-cleaning pads to clean the abrasive blasted parts.
capacity is 91 oz (2.7 L); the remaining oil is used for coating
Do not spin dry the bearings with the compressed air or
the test parts during assembly.
nitrogen. Only use blowguns without a safety bypass to air-dry
16,9
the parts. A Milton model S15 has been found to be
9. Preparation of American Axle & Manufacturing
acceptable.
Hardware
9.2.1.5 Pre-Test Inspection—After the parts have been abra-
9.1 Cleaning of Reused Fittings, Seals, and so forth—Clean,
sive blasted, and before cleaning and rinsing, carefully inspect
as necessary, all reusable parts including axle tube opening
the abrasive blasted parts, bearings, and bearing cups for rust or
seals, pressure relief system and elbow, and the temperature
corrosion and damage. If any rated area is found to have rust,
sensor and its fittings.
re-prepare as described in 9.2.1.4. If defects are found, such as
9.2 Differential Assembly Build-Up:
casting flaws and so forth, that might be mistaken for rust at the
9.2.1 Cleaning and Preparation of Parts:
end of test inspection, add a notation of their pre-test existence
9.2.1.1 Disassembly—Disassemble the differential housing
to the test report. If any bearing is found to have rust or
assembly, leaving the pinion inner and outer races in place.
damage, replace it with a new one that is rust-free. The
Remove and discard the oil drain plug magnet (if present).
replaced bearing shall be from the same manufacturer and have
Remove all parts from the differential case. Disassemble all
the same bearing part number. At the end of test inspection and
bearings from their mating parts. Maintain right differential
rating make no allowances for parts rusted before start of test.
case shim for axle assembly.
9.2.1.6 Test Oil Coating—Immediately coat all abrasive
(1) Be aware that the bolts attaching the ring gear to the
blasted parts evenly with test oil after they have been cleaned,
carrier are left-hand thread.
rinsed, and dried. Immediately coat all four bearings, bearing
9.2.1.2 Differential Housing Modification—Drill and tap the
cups, and differential shaft (cross shaft pin) evenly with test oil
housing to accept the temperature sensor using the template
after they have been cleaned and rinsed. (Bearings, bearing
shown in Figs. A5.12 and A5.13. Install the temperature sensor
cups, and differential shaft (cross shaft pin) are not abrasive
so that the tip of the sensor is 1 in. 6 0.25 in. (25.4 mm 6
blasted). Dipping the parts in test oil or pouring the test oil over
6.4 mm) from the floor of the differential housing as shown in
the parts are acceptable methods. Do not use brushes to coat
Fig. A5.4. Tap the housing vent tube opening to ⁄4 in. NPT to
the parts with test oil. Do not touch any test parts with bare
install the pressure control device.
hands; fingerprints can cause rusting.
9.2.1.3 Cleaning—Pressure wash the differential housing
9.2.1.7 Lightly coat all bolts with test oil prior to assembly
and each individual component with solvent (see 7.2) using a
of test axle.
round plastic bristle brush. Rinse the differential housing and
9.2.1.8 Clean, rinse, dry, and coat all parts with test oil
each individual component with solvent, and dry them with
within 2 h after abrasive blasting.
compressed air or nitrogen. Do not use wire brushes or
9.2.2 Assembly of Test Unit:
abrasive cleaning pads to clean the differential housing and
The sole source of supply of the apparatus known to the committee at this time
The sole source of supply of the apparatus known to the committee at this time is Wilkerson Instrument Company, Inc., 2915 Parkway Street, Lakeland, FL 33811.
is Fisher Scientific, 2000 Park Lane Drive, Pittsburgh, PA 15275. The sole source of supply of the apparatus known to the committee at this time
The sole source of supply of the apparatus known to the committee at this time is McMaster Carr Supply Company, 200 Aurora Industrial Pkwy, Cleveland, OH
is Exxon\Mobil Oil Company, Fairfax, VA. 44202.
D7038 − 23
9.2.2.1 Drive Pinion Shaft Installation—Assemble the drive used to mount the axle housing in the motoring stand. Ensure
pinion shaft with its bearings and install it in the housing that all fasteners used to attach the cover plate are evenly
following the guidelines in 9.2.2. A late model GM, GMC, or torqued to the given specification.
Chevrolet service manual may be used for assembly details not
10. Calibration
included here.
10.1 Reference Test Frequency—Conduct one reference test
(1) Install the rear pinion bearing onto the pinion shaft with
every ten test starts or every five months, whichever comes
the original shim.
first. This calibration frequency is subject to change as re-
(2) Place the front pinion bearing into the housing and then
quired. Current calibration information is available from the
install the pinion front seal into the housing. Note that the front
TMC.
seal might be damaged during disassembly and may need to be
replaced.
10.2 All tests are consecutively numbered on a storage box
(3) Install the pinion shaft into the differential housing. The
basis. Each storage box has its own unique, permanent identi-
front bearing may need to be tapped into place using a small
fier. Every test start shall receive a sequential test run number
punch. Install the pinion yoke washer and nut. Torque pinion-
designated before testing begins. All test starts, including
nut until a turning torque of 3 lbf-in. to 10 lbf-in. (0.3 N·m to
aborted starts and operationally invalid tests, shall retain their
1.1 N·m) is achieved.
test run number.
(4) If necessary, replace the pinion crush collar and repeat
10.3 Consider as non-interpretable any non-reference oil
pinion assembly process.
test that has not been run in a calibrated test stand or not
(5) Record the final pinion break and turning torque on the
conducted on approved hardware, or both. Indicate on the
appropriate test report form.
cover page of the test report that the test is non-interpretable
9.2.2.2 Differential Case Installation—Assemble the differ-
and that it has not been conducted in a valid manner in
ential pinion, side gears, shafts and thrust washers, shims,
accordance with this test method.
bearings, and ring gears. Be aware that the bolts attaching the
10.4 Instrumentation Calibration:
ring gear to the carrier are left-hand thread. Install the
10.4.1 Prior to every stand calibration attempt, calibrate the
differential case assembly and bearing caps in the differential
drive speed measuring system and the temperature control
housing. Torque the differential housing bearing caps to
systems (storage box and motoring stand) against a known
35 lbf-ft to 50 lbf-ft (48 N·m to 68 N·m). Measure break and
standard, traceable to NIST.
turning torque; turn torque shall be 7 lbf-in. to 13 lbf-in.
10.4.2 Prior to every stand calibration attempt, calibrate the
(0.8 N·m to 1.5 N·m) and break torque shall be 8 lbf-in. to
pressure relief system, using the following process:
18 lbf-in. (0.9 N·m to 2.0 N·m).
10.4.2.1 From the bottom of the dip tube, measure 27.75 in.
(1) Adjust the final turning torque by removing the differ-
6 0.125 in. (704.9 mm 6 3.18 mm) and mark this distance on
ential case, adding or removing shims on the left ring gear side
the dip tube.
only, and then reassemble to obtain final preload.
10.4.2.2 Apply 1 psi (6.9 kPa) to the dip tube.
(2) Repeat Item 1 of 9.2.2.2 until the appropriate final
10.4.2.3 Fill the water column reservoir with specified test
turning torque is reached.
water, (see 7.1), until 1 psi (6.9 kPa) is displaced.
(3) Record final break and turning torque in the space
10.4.2.4 Release the pressure in the dip tube, and mark the
provided in the test report.
static water level on the dip tube.
(4) After completion of the test axle build and before the
10.4.2.5 Apply air pressure to the dip tube until air begins to
cover plate installation, place the test axle in a vertical position
bubble from the tube to verify calibration. Air pressure shall be
with the yoke oriented upward. Place the cover in a vertical
1 psi 6 0.1 psi (6.9 kPa 6 0.7 kPa).
position. Allow the assembled test axle and cover plate to drain
for a minimum of 10 min. 11. Test Procedure
9.2.2.3 Test Oil Addition—Charge 91 oz 6 2.3 oz (2.7 L 6
11.1 Pre-Test, Start, and Motoring Phase:
0.07 L) of test oil to the test unit.
11.1.1 Installation of Test Unit—Install the assembled test
9.2.2.4 Cover Plate, Seals, Temperature Probe, and Pres-
unit on the motoring rig. Connect the driveshaft and tempera-
sure Control Valve Installation—Install the cover plate with a
ture probe. Install the cooling fan and heat lamp pair as shown
new TFE fluorocarbon gasket, pre-wetted with the test oil on
in Fig. A5.3.
both sides (see 6.2.4). Use a new TFE fluorocarbon cover plate
11.1.2 Adjust the temperature controller to maintain 180 °F
gasket for every test. Orient the gasket such that the hook on
6 1 °F (83 °C 6 0.6 °C).
the gasket is nearest the tapped vent hole in the axle housing.
11.1.3 Start the driving motor and immediately accelerate
(1) Torque the cover plate bolts to 20 lbf-ft to 25 lbf-ft
the motor to 2500 r ⁄min 6 25 r ⁄min. Record the time and the
(27 N·m to 34 N·m).
initial oil temperature at the time of the driving motor start up.
(2) Install the temperature probe using TFE fluorocarbon
11.1.4 Do not exceed 8 h between the beginnings of the
tape as shown in Fig. A5.4, Fig. A5.11, and Fig. A5.12.
abrasive blasting of axle parts to the start of the motoring phase
(3) Install the NPT stainless steel fittings and stainless steel
of the test.
full port valve into the pre-tapped axle housing vent tube
opening. Some of the cover plate bolts may be replaced with
National Institute of Standards and Technology (formerly National Bureau of
longer bolts or studs which are then used to attach a bracket Standards), Gaithersburg, MD 20899.
D7038 − 23
11.1.5 Using a syringe, add 2.3 oz 6 0.02 oz (67.5 mL 6 11.4.2 Lightly pressure wash all parts with a solvent (see
0.6 mL) of specified test water to the test unit through the full 7.2) to remove used test oil being careful not to remove any
port valve within 5 min after starting the drive motor. Connect small rust spots (pressure not to exceed 30 psi (207 kPa) and
the pressure relief system. without mechanical means such as a brush).
14,9
11.4.3 Coat test parts in Mobil Arma 245 prior to final
11.1.6 Monitor oil temperature and when the oil tempera-
rating.
ture reaches 180 °F 6 1 °F (83 °C 6 0.6 °C), close full port
14,9
11.4.4 Clean and coat all parts in Mobil Arma 245 within
ball valve, disconnect the pressure relief system, and plug the
1 h after disassembling the test axle.
downstream side of valve. This prevents escape of any addi-
11.4.5 If the rating is not to be conducted within 24 h of the
tional water vapor. Measure and record drive pinion r/min and
end of the test, the coated test parts shall either be stored
oil temperature, and report the time at the beginning of
submerged in the preservative oil, or sto
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7038 − 22a D7038 − 23
Standard Test Method for
Evaluation of Moisture Corrosion Resistance of Automotive
Gear Lubricants
This standard is issued under the fixed designation D7038; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Portions of this test method are written for use by laboratories that make use of ASTM Test
Monitoring Center (TMC) services (see Annex A1 – Annex A4).
The TMC provides reference oils, and engineering and statistical services to laboratories that desire
to produce test results that are statistically similar to those produced by laboratories previously
calibrated by the TMC.
In general, the Test Purchaser decides if a calibrated test stand is to be used. Organizations such as
the American Chemistry Council require that a laboratory use the TMC services as part of their test
registration process. In addition, the American Petroleum Institute and the Gear Lubricant Review
Committee of the Lubricant Review Institute (SAE International) require that a laboratory use the
TMC services in seeking qualification of oils against their specifications.
The advantage of using the TMC services to calibrate test stands is that the test laboratory (and
hence the Test Purchaser) has an assurance that the test stand was operating at the proper level of test
severity. It should also be borne in mind that results obtained in a non calibrated test stand may not
be the same as those obtained in a test stand participating in the ASTM TMC services process.
Laboratories that choose not to use the TMC services may simply disregard these portions.
ASTM International policy is to encourage the development of test procedures based on generic
equipment. It is recognized that there are occasions where critical/sole-source equipment has been
approved by the technical committee (surveillance panel/task force) and is required by the test
procedure. The technical committee that oversees the test procedure is encouraged to clearly identify
if the part is considered critical in the test procedure. If a part is deemed to be critical, ASTM
encourages alternative suppliers to be given the opportunity for consideration of supplying the critical
part/component providing they meet the approval process set forth by the technical committee.
An alternative supplier can start the process by initiating contact with the technical committee
(current chairs shown on ASTM TMC website). The supplier should advise on the details of the part
that is intended to be supplied. The technical committee will review the request and determine
feasibility of an alternative supplier for the requested replacement critical part. In the event that a
replacement critical part has been identified and proven equivalent, the sole-source supplier footnote
shall be removed from the test procedure.
1. Scope*
1.1 This test method covers a test procedure for evaluating the rust and corrosion inhibiting properties of a gear lubricant while
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.B0 on Automotive Lubricants.
Current edition approved July 1, 2022Nov. 1, 2023. Published July 2022November 2023. Originally approved in 2004. Last previous edition approved in 2022 as
D7038 – 22.D7038 – 22a. DOI: 10.1520/D7038-22A.10.1520/D7038-23.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7038 − 23
subjected to water contamination and elevated temperature in a bench-mounted hypoid differential housing assembly. This test
method is commonly referred to as the L-33-1 test.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.2.1 Exceptions—(1) where there is no direct SI equivalent such as screw threads and national pipe threads/diameters, and (2)
the values stated in SI units are to be regarded as standard for the definitions in 12.2, and for SI units where there are no direct
inch-pounds equivalent units.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D235 Specification for Mineral Spirits (Petroleum Spirits) (Hydrocarbon Dry Cleaning Solvent)
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
2.2 Society of Automotive Engineers Standards:
J308 Information Report on Axle and Manual Transmission Lubricants
J2360 Lubricating Oil, Gear Multipurpose (Metric) Military Use
2.3 U.S. Military Specifications:
MIL-PRF-2105E Lubricating Oil, Gear, General Multipurpose
MIL-P-3420F NOX-RUST Paper
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 corrosion, n—an alteration of a finished metal surface by discoloration, accompanied by roughening not attributable to
mechanical action.
3.1.2 downtime, n—an interruption of power to the test unit for a period greater than ten seconds.
3.1.3 rust, n—a special case of corrosion, which always deteriorates or alters the original surface condition.
3.1.3.1 Discussion—
Rust always has color (usually, but not limited to red, yellow, brown, black) and one of the following descriptive characteristics:
(1) depth; the rusted surface is built up relative to that of adjacent areas. (2) texture; the surface may appear to be etched, scaly
or otherwise visibly different than adjacent areas.
3.1.4 stain, n—a surface modification that is attributable to discoloration only.
4. Summary of Test Method
4.1 This procedure uses a new hypoid differential assembly as the primary test unit. The differential assembly is installed on a
motoring rig and charged with test lubricant and a small amount of water. The test unit is then sealed and driven until the lubricant
temperature has increased to 180 °F (82.2 °C). The motoring phase is continued for 4 h and the test unit is then removed from the
Until the next revision of this test method, the ASTM Test Monitoring Center (TMC) will update changes in this test method by means of Information Letters. This edition
includes all Information Letters through 22-2.23-1. Information Letters may be obtained from the ASTM Test Monitoring Center, 203 Armstrong Drive, Freeport, PA 16229,
Attention: Director.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale, PA 15096, http://www.sae.org.
Available from the Defense Printing Service Office, 700 Robbins Ave., Bldg. 4D, Philadelphia, PA 19111-5094.
D7038 − 23
motoring rig and placed in a storage box for 162 h with the lubricant temperature controlled at 125 °F (51.7 °C). The test is
completed at that time and the differential assembly is drained, disassembled, and inspected for rust, stain, and other deposits.
5. Significance and Use
5.1 This test simulates a type of severe field service in which corrosion-promoting moisture in the form of condensed water vapor
accumulates in the axle assembly. This may happen as a result of volume expansion and contraction of the axle lubricant and the
accompanied breathing in of moisture-laden air through the axle vent. The test screens lubricants for their ability to prevent the
expected corrosion.
5.2 The L-33-1 test procedure is used or referred to in the following documents: ASTM Publication STP-512A, SAE J308, SAE
J2360, and U.S. Military Specification MIL-PRF-2105E.
6. Apparatus
6.1 Laboratory Ambient Conditions:
6.1.1 Test Operating Area—The ambient laboratory atmosphere shall be free of dirt, dust, and other contaminants as required by
good laboratory standards.
6.1.2 Parts Cleaning and Abrasive Blasting (6.2.8) Areas—Provide adequate ventilation in areas where solvents (7.2) are used.
(Warning—Combustible, vapor harmful.)
6.1.3 Build-up Area—It is recommended that the atmosphere in the test unit build-up area be filtered and maintained at uniform
temperature and low humidity to prevent accumulation of dirt or rust on test parts. Otherwise it shall conform to requirements of
6.1.1.
6.1.4 Parts Rating Area—Conduct the rating of all test parts under conditions as defined in ASTM Distress Rating Manual 21.
6.2 Test Unit—This procedure uses a hypoid differential assembly (without axle tubes). See the critical parts list under the L-33-1
Information Letter section of the Test Monitoring Center website, www.astmtmc.org, for hardware approved for test use.
6.2.1 Mount the differential housing assembly on the motoring rig so that the housing cover attaching face is in the vertical plane
and at a height that allows the temperature sensing probe to be located in the bottom of the housing. Elements of the motoring rig
design are shown in Figs. A5.1-A5.4.
6.2.2 Drive System—The drive system design is not precisely specified; however, the following equipment or its equivalent have
been found to be suitable to turn the drive pinion at the specified 2500 r ⁄min 6 25 r ⁄min. (Warning—Rotating test stand
equipment presents a physical hazard, use safety guards.)
6.2.2.1 Electric Motor, approximately 2.0 hp (1.5 kW), enclosed, 3600 r ⁄min, 0.87 in. (22.2 mm) diameter shaft.
6.2.2.2 Slide Motor Base, Dyn-Adjust No. 20-C.
6.2.2.3 Dodge Taper Lock Pulleys, No. 40L100 (Driven) and No. 28L100 (Drive).
6.2.2.4 Dodge Timing Belt, No. 480L100.
6.2.2.5 Additional components such as shafts, couplings, and bearing blocks are also necessary to connect the above components
to drive the carrier pinion, but are left to the option of the testing laboratory.
6.2.3 Vapor Pressure Control System—Control the internal vapor pressure of the unit during the warm-up portion of the motoring
phase with a specified water column pressure relief system set for 1.0 psi 6 0.1 psi (7 kPa 6 0.7 kPa) connected to the housing
cover with an appropriately sized National Pipe Threads (NPT) stainless steel 90° street ell and a stainless steel full port valve.
ASTM Publication STP-512A, Laboratory Performance Tests for Automotive Gear Lubricants Intended for API GL-5 Service, ASTM International, West Conshohocken,
PA.
For stock #TMCMNL21, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail].
D7038 − 23
The system shall contain an oil trap and return vessel to return test oil to the unit in case of foaming, and a water trap and return
vessel to prevent column water from moving back to test unit. The example set up in Fig. A5.1 has been shown to be acceptable.
8,9
6.2.4 Housing Cover Gasket—Replace the factory-supplied gasket with a single TFE fluorocarbon gasket for every test.
6.2.5 Housing Axle Tube Opening Seals—Since the differential is tested without axle shafts or axle tubes, use a stainless steel
plumbing test plug for a 2.9 in. to 3.1 in. (74 mm to 79 mm) pipe diameter to seal the housing openings. McMasterCarr p/n
11,9
2908K28 or 2908K29 with the outer washer and seal ring cut to 2.9 in. to 3.1 in. (74 mm to 79 mm) has been found acceptable
for this purpose. Install a pair of seals in the axle housing openings before installing carrier/case into the axle housing.
6.2.6 Temperature Control System, Motoring Phase—During the motoring phase, the bulk oil temperature is sensed by a resistance
temperature device (RTD) or thermocouple (J (E, J, or K type). The controller switches on a pair of 250 W lamps or cooling fan,
or both, that are directed toward the differential as needed to control bulk oil temperature at 180 °F 6 1 °F (82 °C 6 0.6 °C). A
household-type electric fan having 12.0 in. (310 mm) diameter blades has been shown to provide acceptable cooling capability.
Fig. A5.3 shows an example of the location of the heat lamp pair and the cooling fan. Fig. A5.4 shows the location of the
temperature sensor in the differential housing.
6.2.7 Storage Box and Temperature Control System, Storage Phase—During the storage phase of the test, a double-walled
aluminum or stainless steel box covers the differential housing assembly. An RTD or thermocouple (J (E, J, or K type) in
conjunction with the controller regulates heat input from four strip heaters giving a total output of 1700 Btu ⁄h (500 W). A small
electric motor turns a fabricated impeller at 1700 r ⁄min 6 100 r ⁄min to provide air circulation within the box. Dayton part number
10,9
3M562 available from Grainger has been found suitable for this purpose. Control the bulk oil temperature at 125 °F 6 1 °F
(52 °C 6 0.6 °C). Fig. A5.5 shows details of the impeller. Fig. A5.6 shows construction and electrical details of this box.
NOTE 1—Insulation on the outside surface of the box only may be necessary to maintain test temperature specifications.
6.2.8 Abrasive Blasting—Blast the entire differential case, ring, pinion, side gears, differential pinion gears (spider gears), all four
thrust washers and the inside surface of the differential housing cover plate with 80 grit aluminum oxide so as to remove
pre-existing corrosion and produce a uniform surface. Do not abrasive blast the bearings, bearing cups and differential shaft (cross
shaft pin). (Warning—Provide adequate safety equipment for abrasive blasting operations.)
6.2.9 The following specifies the abrasive blasting equipment and material:
10,9
6.2.9.1 Abrasive Blasting Cabinet—Grainger Econo-Line 36 in. by 24 in., Grainger Item No. 3Z850.
(1) Use solely for cleaning L-33-1 test units.
(2) Measure air pressure for the blasting gun at the regulator just prior to entering the cabinet enclosure. Set the regulator to
maintain 80 psig 6 2 psig (552 kPa 6 14 kPa) while flowing abrasive material.
3 10,9
6.2.9.2 Dust Collector—Grainger Econo-Line 1000 ft /min, Grainger Item No. 3JR93.
6.2.9.3 Blasting Gun Setup:
3 10,9
(1) Grainger Econo-Line 12 ft /min Gun Assembly, Grainger Item No. 3JT01.
10,9
(2) Grainger Econo-Line tungsten carbide Nozzle Tip ⁄4 in. I.D. Grainger Item No. 3JT08. Take care to install this nozzle
with the smaller opening facing out. The nozzle’s shape makes it possible for it to be installed incorrectly. Change the nozzle after
fifteen L-33-1 units are blasted.
3 10,9
(3) Grainger Econo-Line Air Jet 12 ft /min, Grainger Item No. 3JT04.
11,9 12,9
6.2.9.4 Abrasive Blasting Material—Alodur Fused Brown Aluminum Oxide, 80 grit—ANSI Table 3 Grade. Change the
entire cabinet supply of abrasive blasting material after 15 L-33-1 units are blasted. (Warning—Abrasive blasting presents a
physical hazard; consult and follow equipment manufacturer’s precautions.)
The sole source of supply of the apparatus known to the committee at this time is AP Services Inc., 18001 Sheldon Road, Middleburg Heights, OH 44130. Request ASTM
L-33-1 Die.
If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a
meeting of the responsible technical committee, which you may attend.
The sole source of supply for this material known to the committee at this time is Imerys Fused Materials Niagara Falls, Inc., 2000 College Avenue, M.P.O. Box 1438,
Niagara Falls, NY 14302, USA.
The sole source of supply of the apparatus known to the committee at this time is Grainger Inc., 120 Beta Drive, Pittsburgh PA 15238.
The sole source of supply of the apparatus known to the committee at this time is the American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New
York, NY 10036.
D7038 − 23
7. Reagents and Materials
13,9
7.1 Specified Test Water—Fisher Scientific deionized ultra filtered water, Part No. W2-4 or W2-20.
7.2 Solvent—Use only mineral spirits meeting the requirements of Specification D235, Type II, Class C for Aromatic Content 0 %
to 2 % vol, Flash Point (142 °F ⁄61 °C, min) and Color (not darker than +25 on Saybolt Scale or 25 on Pt-Co Scale).
(Warning—Combustible. Health hazard.) Obtain a Certificate of Analysis for each batch of solvent from the supplier.
14,9
7.3 Rust Prevention Oil—Mobil Arma 245. (Warning—Combustible mixture. Harmful or fatal if swallowed.)
7.4 Build-up Lubricant—Use test oil for test unit build-up.
8. Test Oil
8.1 Use 1.0 gal (3.7 L) of fluid for each test. The housing capacity is 91 oz (2.7 L); the remaining oil is used for coating the test
parts during assembly.
9. Preparation of American Axle & Manufacturing Hardware
9.1 Cleaning of Reused Fittings, Seals, and so forth—Clean, as necessary, all reusable parts including axle tube opening seals,
pressure relief system and elbow, and the temperature sensor and its fittings.
9.2 Differential Assembly Build-Up:
9.2.1 Cleaning and Preparation of Parts:
9.2.1.1 Disassembly—Disassemble the differential housing assembly, leaving the pinion inner and outer races in place. Remove
and discard the oil drain plug magnet (if present). Remove all parts from the differential case. Disassemble all bearings from their
mating parts. Maintain right differential case shim for axle assembly.
(1) Be aware that the bolts attaching the ring gear to the carrier are left-hand thread.
9.2.1.2 Differential Housing Modification—Drill and tap the housing to accept the temperature sensor using the template shown
in Figs. A5.12 and A5.13. Install the temperature sensor so that the tip of the sensor is 1 in. 6 0.25 in. (25.4 mm 6 6.4 mm) from
the floor of the differential housing as shown in Fig. A5.4. Tap the housing vent tube opening to ⁄4 in. NPT to install the pressure
control device.
9.2.1.3 Cleaning—Pressure wash the differential housing and each individual component with solvent (see 7.2) using a round
plastic bristle brush. Rinse the differential housing and each individual component with solvent, and dry them with compressed
air or nitrogen. Do not use wire brushes or abrasive cleaning pads to clean the differential housing and individual components.
Remove all grease and oil used during manufacturer’s assembly from bearings and wipe clean lip seals with a dry cloth.
9.2.1.4 Functional Surface and Cover Plate Preparation—Abrasive blast the entire differential case, ring, pinion, side gears,
differential pinion gears (spider gears), all four thrust washers and the inside surface of the housing cover plate by uniformly
abrasive blasting with 80 grit aluminum oxide. Do not abrasive blast the bearings, bearing cups and differential shaft (cross shaft
pin). Do not touch any cleaned surface with bare hands as moisture can cause rusting.
(1) After abrasive blasting and pre-test inspection (see 9.2.1.5), pressure wash abrasive blasted parts, all four bearings, and
bearing cups with solvent and a round plastic bristle brush (pressure not to exceed 30 psi (207 kPa) (see 6.1.2). After pressure
washing, rinse with solvent and dry with filtered compressed air or nitrogen (pressure not to exceed 30 psi (207 kPa) (see 7.2). A
15,9
Wilkerson filter, model M18-02-CH00 is required to filter the compressed air or nitrogen. A Wilkerson model MTP-96-
15,9
64617 is the required replacement element for the filter assembly. Do not use wire brushes or abrasive-cleaning pads to clean
the abrasive blasted parts. Do not spin dry the bearings with the compressed air or nitrogen. Only use blowguns without a safety
16,9
bypass to air-dry the parts. A Milton model S15 has been found to be acceptable.
The sole source of supply of the apparatus known to the committee at this time is Fisher Scientific, 2000 Park Lane Drive, Pittsburgh, PA 15275.
The sole source of supply of the apparatus known to the committee at this time is Exxon\Mobil Oil Company, Fairfax, VA.
The sole source of supply of the apparatus known to the committee at this time is Wilkerson Instrument Company, Inc., 2915 Parkway Street, Lakeland, FL 33811.
The sole source of supply of the apparatus known to the committee at this time is McMaster Carr Supply Company, 200 Aurora Industrial Pkwy, Cleveland, OH 44202.
D7038 − 23
9.2.1.5 Pre-Test Inspection—After the parts have been abrasive blasted, and before cleaning and rinsing, carefully inspect the
abrasive blasted parts, bearings, and bearing cups for rust or corrosion and damage. If any rated area is found to have rust,
re-prepare as described in 9.2.1.4. If defects are found, such as casting flaws and so forth, that might be mistaken for rust at the
end of test inspection, add a notation of their pre-test existence to the test report. If any bearing is found to have rust or damage,
replace it with a new one that is rust-free. The replaced bearing shall be from the same manufacturer and have the same bearing
part number. At the end of test inspection and rating make no allowances for parts rusted before start of test.
9.2.1.6 Test Oil Coating—Immediately coat all abrasive blasted parts evenly with test oil after they have been cleaned, rinsed, and
dried. Immediately coat all four bearings, bearing cups, and differential shaft (cross shaft pin) evenly with test oil after they have
been cleaned and rinsed. (Bearings, bearing cups, and differential shaft (cross shaft pin) are not abrasive blasted). Dipping the parts
in test oil or pouring the test oil over the parts are acceptable methods. Do not use brushes to coat the parts with test oil. Do not
touch any test parts with bare hands; fingerprints can cause rusting.
9.2.1.7 Lightly coat all bolts with test oil prior to assembly of test axle.
9.2.1.8 Clean, rinse, dry, and coat all parts with test oil within 2 h after abrasive blasting.
9.2.2 Assembly of Test Unit:
9.2.2.1 Drive Pinion Shaft Installation—Assemble the drive pinion shaft with its bearings and install it in the housing following
the guidelines in 9.2.2. A late model GM, GMC, or Chevrolet service manual may be used for assembly details not included here.
(1) Install the rear pinion bearing onto the pinion shaft with the original shim.
(2) Place the front pinion bearing into the housing and then install the pinion front seal into the housing. Note that the front
seal might be damaged during disassembly and may need to be replaced.
(3) Install the pinion shaft into the differential housing. The front bearing may need to be tapped into place using a small punch.
Install the pinion yoke washer and nut. Torque pinion-nut until a turning torque of 3 lbf-in. to 10 lbf-in. (0.3 N·m to 1.1 N·m) is
achieved.
(4) If necessary, replace the pinion crush collar and repeat pinion assembly process.
(5) Record the final pinion break and turning torque on the appropriate test report form.
9.2.2.2 Differential Case Installation—Assemble the differential pinion, side gears, shafts and thrust washers, shims, bearings, and
ring gears. Be aware that the bolts attaching the ring gear to the carrier are left-hand thread. Install the differential case assembly
and bearing caps in the differential housing. Torque the differential housing bearing caps to 35 lbf-ft to 50 lbf-ft (48 N·m to
68 N·m). Measure break and turning torque; turn torque shall be 7 lbf-in. to 13 lbf-in. (0.8 N·m to 1.5 N·m) and break torque shall
be 8 lbf-in. to 18 lbf-in. (0.9 N·m to 2.0 N·m).
(1) Adjust the final turning torque by removing the differential case, adding or removing shims on the left ring gear side only,
and then reassemble to obtain final preload.
(2) Repeat Item 1 of 9.2.2.2 until the appropriate final turning torque is reached.
(3) Record final break and turning torque in the space provided in the test report.
(4) After completion of the test axle build and before the cover plate installation, place the test axle in a vertical position with
the yoke oriented upward. Place the cover in a vertical position. Allow the assembled test axle and cover plate to drain for a
minimum of 10 min.
9.2.2.3 Test Oil Addition—Charge 91 oz 6 2.3 oz (2.7 L 6 0.07 L) of test oil to the test unit.
9.2.2.4 Cover Plate, Seals, Temperature Probe, and Pressure Control Valve Installation—Install the cover plate with a new TFE
fluorocarbon gasket, pre-wetted with the test oil on both sides (see 6.2.4). Use a new TFE fluorocarbon cover plate gasket for every
test. Orient the gasket such that the hook on the gasket is nearest the tapped vent hole in the axle housing.
(1) Torque the cover plate bolts to 20 lbf-ft to 25 lbf-ft (27 N·m to 34 N·m).
(2) Install the temperature probe using TFE fluorocarbon tape as shown in Fig. A5.4, Fig. A5.11, and Fig. A5.12.
(3) Install the NPT stainless steel fittings and stainless steel full port valve into the pre-tapped axle housing vent tube opening.
Some of the cover plate bolts may be replaced with longer bolts or studs which are then used to attach a bracket used to mount
the axle housing in the motoring stand. Ensure that all fasteners used to attach the cover plate are evenly torqued to the given
specification.
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10. Calibration
10.1 Reference Test Frequency—Conduct one reference test every ten test starts or every five months, whichever comes first. This
calibration frequency is subject to change as required. Current calibration information is available from the TMC.
10.2 All tests are consecutively numbered on a storage box basis. Each storage box has its own unique, permanent identifier. Every
test start shall receive a sequential test run number designated before testing begins. All test starts, including aborted starts and
operationally invalid tests, shall retain their test run number.
10.3 Consider as non-interpretable any non-reference oil test that has not been run in a calibrated test stand or not conducted on
approved hardware, or both. Indicate on the cover page of the test report that the test is non-interpretable and that it has not been
conducted in a valid manner in accordance with this test method.
10.4 Instrumentation Calibration:
10.4.1 Prior to every stand calibration attempt, calibrate the drive speed measuring system and the temperature control systems
(storage box and motoring stand) against a known standard, traceable to NIST.
10.4.2 Prior to every stand calibration attempt, calibrate the pressure relief system, using the following process:
10.4.2.1 From the bottom of the dip tube, measure 27.75 in. 6 0.125 in. (704.9 mm 6 3.18 mm) and mark this distance on the
dip tube.
10.4.2.2 Apply 1 psi (6.9 kPa) to the dip tube.
10.4.2.3 Fill the water column reservoir with specified test water, (see 7.1), until 1 psi (6.9 kPa) is displaced.
10.4.2.4 Release the pressure in the dip tube, and mark the static water level on the dip tube.
10.4.2.5 Apply air pressure to the dip tube until air begins to bubble from the tube to verify calibration. Air pressure shall be 1 psi
6 0.1 psi (6.9 kPa 6 0.7 kPa).
11. Test Procedure
11.1 Pre-Test, Start, and Motoring Phase:
11.1.1 Installation of Test Unit—Install the assembled test unit on the motoring rig. Connect the driveshaft and temperature probe.
Install the cooling fan and heat lamp pair as shown in Fig. A5.3.
11.1.2 Adjust the temperature controller to maintain 180 °F 6 1 °F (83 °C 6 0.6 °C).
11.1.3 Start the driving motor and immediately accelerate the motor to 2500 r ⁄min 6 25 r ⁄min. Record the time and the initial oil
temperature at the time of the driving motor start up.
11.1.4 Do not exceed 8 h between the beginnings of the abrasive blasting of axle parts to the start of the motoring phase of the
test.
11.1.5 Using a syringe, add 2.3 oz 6 0.02 oz (67.5 mL 6 0.6 mL) of specified test water to the test unit through the full port valve
within 5 min after starting the drive motor. Connect the pressure relief system.
11.1.6 Monitor oil temperature and when the oil temperature reaches 180 °F 6 1 °F (83 °C 6 0.6 °C), close full port ball valve,
disconnect the pressure relief system, and plug the downstream side of valve. This prevents escape of any additional water vapor.
Measure and record drive pinion r/min and oil temperature, and report the time at the beginning of motoring phase. Allow a 1 h
maximum warm up time for the oil to reach operating temperature of 180 °F 6 1 °F (83 °C 6 0.6 °C).
National Institute of Standards and Technology (formerly National Bureau of Standards), Gaithersburg, MD 20899.
D7038 − 23
11.1.6.1 Occasionally, a small amount of the test oil and water emulsion will foam up from the axle housing into the accumulator
during warm-up. Make every effort to allow the test oil and water emulsion to return to the test axle. Stop the motoring and heating
of the test unit in an attempt to return the test oil and emulsion to the test axle. There may be occasions when the test oil and water
emulsion will not completely drain back into the carrier as the unit reaches operating temperature. Use caution not to exceed the
1 h maximum warm-up time. Report the number of shutdowns and the estimated amount of test oil and water emulsion that did
not return to the carrier in the comment section of the test report.
11.1.7 Motor the test unit for 4.0 h 6 0.1 h at 180 °F 6
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