ASTM D7038 Standard Test Method for Evaluation of Moisture Corrosion Resistance of Automotive Gear Lubricants
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) made by American Axle Mfg. The model designation is K2XX, Part No. P40128429A, 3:42 ratio, standard 218.4 mm (8.6 in.). This is an open differential with uncoated ring and pinion. Until June 23, 2017, a Dana Model 30 V01.1 may also be used.
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 +/- 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 +/- 0.1 psi (7 kPa +/- 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. 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.

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, seal the housing openings. Use a stainless steel plumbing test plug for a 2.9 in. to 3.1 in. pipe diameter. McMasterCarr p/n 2908K28 with the outer washer and seal ring cut to 74 mm to 79 mm (2.9 in. to 3.1 in.) has been found acceptable. Install a pair of seals in the axle housing openings before installing carrier/case into the axle housing. When using Dana Model 30 hardware rather than the AAM K2XX hardware see Fig. A5.2 for an example of construction dimensions for fabricating a pair of suitable seals.

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 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 +/- 1 °F (82 °C +/- 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 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 fan, rated at 1550 r/min, turns a fabricated impeller at 1700 r/min +/- 100 r/min to provide air circulation within the box. Control the bulk oil temperature at 125 °F +/- 1 °F (52 °C +/- 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:
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 +/- 2 psig (552 kPa +/- 14 kPa) while flowing abrasive material.

6.2.9.2 Dust Collector - Grainger Econo-Line 1000 ft3/min, Grainger Item No. 3JR93.

6.2.9.3 Blasting Gun Setup:
(1) Grainger Econo-Line 12 ft3/min Gun Assembly, Grainger Item No. 3JT01.
(2) Grainger Econo-Line tungsten carbide Nozzle Tip 1/4 in. I.D.
(3) Grainger Item No. 3JT0813, Change after fifteen L-33-1 units are blasted.
(4) Grainger Econo-Line Air Jet 12 ft3/min, Grainger Item No. 3JT04.

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.)

7. Reagents and Materials
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.

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 disassembly. When using Dana model 30 hardware rather than the AAM K2XX hardware the housing capacity is 40 oz (1.2 L).