Elite among lubricants
The modern CV joints are built to handle high torque and heavy loads, both mechanical and thermal. Their longevity depends on a reliable lubricant inside a hermetically sealed housing made of rubber, plastic, or silicone. When the seal is tight, the joint’s lifespan can rival the vehicle’s overall life. In practice, seals can fail from external factors, and when replacement is needed, the lubricant must be fully renewed.
Using grease without consideration can prematurely wear the CV joint. Therefore, selecting the right lubricant is essential.
What Are Lubricants?
Different greases are used for ball and tripod joints. The key difference is that graphite and molybdenum compounds are essential in lubricants for ball joints. Such greases must withstand heavy loads, provide excellent extreme pressure performance, and remain stable over time even in the presence of water and dirt. This is the top tier of greases, so it is not always wise to use them only in ball and socket joints.
Tripod joint lubricants tend to be simpler, and solid additives are generally avoided in them.
For testing, eleven ball joint assemblies were evaluated with similar purposes.
Test Welds
The aim was to compare tribological properties of lubricants in accordance with a standard specification. A four-ball friction machine, known in some regions as Burlage or ChShM, is used to study friction and wear characteristics with the tested lubricant.
A standard CSM device comprises three fixed steel balls in a cup and one movable ball above. The top ball rotates relative to the others at a set speed and load until welding occurs or the specified friction torque is reached.
The field of tribology covers friction, wear, and lubrication processes. In this study, a four-ball ChMT-1 friction machine and an MPB-2 microscope were employed to determine three parameters:
- D — the average wear diameter of the balls at an axial load of 392 N and a test duration of 1 hour;
- hp — critical load;
- PC — the burden of ball welding or reaching the friction moment of 1180 ± 25 N·cm.
The phrase rolling in oil refers to testing on a four-ball machine. The welding load is the smallest load at which the machine stops automatically upon reaching the friction torque or when the balls weld together. The critical load is more modest: it is defined by the average wear diameter of the lower balls within permissible limits.
When the top ball welds to the bottom balls, a critical load is reached that the grease must withstand. The test is comparative: smaller wear spots are better, and higher loads are preferable for endurance.
Members
Two Leaders and Two Failures
Greases with a contact surface diameter exceeding 1 mm are not recommended. For the Luxe composition, this parameter reached 1.35 mm, indicating the CV joint would wear out three times faster than with Gazpromneft or Elf lubricants, which performed best in the tests.
SHRUS lubricant test results
| Example name | Characteristics |
| Tue, mm | PK, H |
| Carville Racing G5150203 | 0.70 |
| Eleven MultiMoS2 | 0.50 |
| Gaspromneft | 0.55 |
| Liqui Moly LM 47 | 0.75 |
| Luxurious SHRUS superb | 1.35 |
| Unil Opal Molith EP | 0.80 |
| Oil law SHRUS-4 | 1.20 |
| Ravenol | 1.00 |
| Schmierfett fur GKN-BruMoly CE 1/2 | 0.95 |
| Schmierfett fur MoS2-G 6.2 | 0.75 |
| VMPAUTO SHRUS | 0.70 |
The results refer only to the specific samples tested and should not be used to judge products with the same name in general. The study acknowledges the team at the Talis laboratory for their support in preparing the material.
- You can read here how drivers damage their own cars.
- Drive can now be read in Telegram.