Limited-Slip Axle Additive is a special additive used to modify the frictional characteristics of axle lubricants for use in limited-slip differentials. It helps to eliminate chatter in limited-slip differentials when added to non-limited-slip API GL-5 gear lubricants.
What Is a Limited Slip Differential?
Limited slip differentials transmit equal torque to both wheels when driving straight. However, when one-wheel spins due to loss of traction, a patch of ice, mud, too much throttle, etc., then the unit automatically provides more power to the wheel that has traction. Highly effective for daily driving and works well in rain, mud, and snow. However, in situations where absolute lockup is needed, a limited slip is not the best choice since limited slips do slip in some situations. An example of it slipping would be with one tire in the air. This does not provide enough resistance and the differential acts like it’s open or standard counterpart.
Limited slips generally are a driven by a series of clutch disc located behind the side gears. The different disc is held under tension with springs. As the slip increases the tension increases between the different layers of disc and provides resistance to limit the slip between the wheels. A draw back to this is that they need to be rebuilt as they do wear, and their effectiveness diminishes over time. A special additive is also needed for the differential fluid to enable the clutches to work properly and to keep them from chattering during normal turns.
What Does a Limited-Slip Additive Do?
Limited-slip differentials commonly use clutches to transmit torque between wheels. When both wheels have ample traction, the clutch plates bind together tightly, but smoothly slip enough to allow chatter-free turning.
When one-wheel spins on a patch of ice or mud, however, additional power is sent to the other wheel through the clutch pack. This is where the gear lubricant’s frictional properties play an important role in performance and wear.
Clutch Chatter
Differential manufacturers use different spring pressures and clutch discs made with different materials and surface areas. Additionally, spring tension and clutch-friction properties change with age and wear, while the frictional requirements of the gear lubricant can vary.
If the frictional properties are not correct, abnormal clutch engagement and disengagement – called chatter – can occur.
Chatter occurs when the clutches repeatedly alternate between slipping and sticking instead of smoothly slipping. It not only generates annoying noise and vibration, but it also causes premature wear.
What Does a Limited-Slip Additive Do?
Instead of formulating multiple gear lubes of the same viscosity, but different frictional properties, to address occasional chatter in limited-slip differentials, gear-lube friction-modifier additives can be used to alter the fluid’s original frictional properties and eliminate chatter.
Differential Additive is formulated with advanced friction modifiers and is designed to eliminate gear-housing chatter in cars, trucks and SUVs equipped with limited-slip, posi-traction and locking differentials. It also reduces the banging and clunking associated with automatic locking differentials.
However, depending on the differential’s friction material and degree of clutch wear, chatter can still sometimes occur.
Finally
Friction modifier makes the fluid “slicker” so without the additive the limited slip clutches will grab and it will shudder going around tight turns. Eventually it will destroy the clutches and render the limited slip useless. If you run a gear oil that has no friction modifier in it the differential will act more like an open differential. In short it will decrease the function of the limited slip differential. It won’t cause any material damage.
If you use non LS oils the differential will try to stick and remain locked.