ASSEMBLY SEQUENCE

The sequence in which these pieces occur inside the case is as follows:

• Friction Plate or Spring Plate
• Friction Disk or Spring Disk
• Friction Plate
• Friction Disk
• Friction Plate
• Friction Disk
• Pressure Ring
• Side Gear
• Pinion Shaft with Pinion Gears
• Side Gear
• Pressure Ring
• Friction Disk
• Friction Plate
• Friction Disk
• Friction Plate
• Friction Disk or Spring Disk
• Friction Plate or Spring Plate

Here are all the parts laid out in something resembling their order of assembly.

FUNCTIONING

This arrangement creates a stack of alternating disks and plates that sits between the end of the case and the pressure ring on each side. The disks are "connected" to the side gear and the plates are "connected" to the case, both by the tab-in-groove arrangement. If a side gear tries to rotate at a different speed than the case, it causes the disks to drag between the plates. This friction is what provides the limited-slip action.

The amount of resistance to slip is determined by the amount of power being applied - the more power, the more resistance. Here is how it does it.

The power is actually applied to the ring gear by the pinion gear (the main pinion gear, as in ring and pinion). The ring gear is bolted to the case, so the case turns. The pressure rings inside the case are forced to turn with the case because the tabs on the pressure rings are inside the grooves in the case. The pressure rings transmit the force to the pinion shaft, which is trapped between them in those v-shaped grooves. The pinion shaft pushes on the pinion gears and thence on the side gears.

When the pressure rings push on the pinion shaft, the weight of the car resists. The fact that the pinion shaft is sitting in the v-groove causes a spreading force to be applied to the pressure rings. This pressure squeezes the friction plates and disks together, increasing their resistance to slippage. If your unit does not have the Belleville spring plates and disks, then this action will be quite sudden. The Belleville springs allow for a gradual increase in slip resistance before lock-up occurs.

How much slip are we really talking about here? Well, if you do the math on turn radii and tire travel distances, you will find that in ANY 180 degree turn, the outside tire travels about 2 revolutions more than the inside tire, regardless of the radius of the turn. For a car with a 50" rear track, the difference in a 300 ft radius turn is 13.09 ft. For the same car in a 30 ft radius turn, the difference is 13.09 ft. A 23" diameter tire has a circumference of 72.26" or just barely over 6 ft. So when you take that 180 degree sweeper going onto your favorite freeway, the outside tire goes an additional 2 revolutions. And when you take that 180 degree around the cone in your favorite parking lot, the outside tire goes an additional 2 revolutions.

So what's the difference? The difference is the amount of time it takes to do those two revolutions. On the freeway ramp, it may take 10 or 15 seconds, while at the autocross it will take maybe half that. So the relative speed of the surfaces in the LSD unit is different and you will feel it as being tighter at the autocross.