How a Limited Slip Differential Works

While off-road guys need absolute locked out traction; high performance drivers on a paved road need a differential that will still provide a forward lock and a limited amount of lock while turning for maximum drive off of the corner.

So how do we achieve that hard lock out of a corner without having the difficult time of trying to drive with both wheels spinning the same speeds all the time?

By using a device called a limited slip differential also known as LSD. Specifically, we’ll be talking about the clutch-type LSD in this article.

So, what makes this so different from a locker? Well, noise is the biggest difference you’ll notice right away. Lockers make so much noise due to the teeth ramping and slamming back into each other in order to lock back up. Clutch-type LSDs, on the other hand, utilize clutch packs to limit the slip between the tires.

On certain types of Clutch-type LSDs, you won’t see the center pin attached to the differential case. Instead, the center pin rides inside the ramp assemblies where the spider gears are located. In Auburn and Trac-Lok differentials, the center pin still does attach to the differential case. There is a spring inside the LSD, however it only acts as a preload.

Another difference is how the lock-up action occurs. Instead of being either locked or unlocked, but not in between, a clutch-type LSD can put pressure on the clutches to increase the break-away torque required and allow slip when that happens. The clutch-type LSD can also provide a lock-up during deceleration. This is done by the ramp assembly and how it interacts with the center pin.

That design can make an LSD act as a 1-way, 1.5-way, or 2-way. A 1-way LSD will only lock on acceleration and will be open on deceleration because the center pin will be flat along with the deceleration side of the carrier.

A 1.5-way LSD will have a wider ramp on the deceleration side to provide some lock-up during deceleration. Then a 2-way will provide lock-up on acceleration and deceleration with equal force as both ramps are the same shape.

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Check out these videos on the clutch-type LSD:

How LSDs work

1-way, 2-way, 1.5-way Explained

Understanding Limited Slip Differential (Trac-Lok Style)