Ramp rider limited slip differentials are one of the most common LSD designs used in motorsport and performance vehicles. They are particularly popular in drifting, circuit racing, and high-performance street builds because they allow the locking behaviour of the differential to be carefully tuned.
Unlike some clutch-type LSD units that rely mainly on spring preload, ramp rider differentials use ramp angles and pressure rings to apply force to the clutch packs when drivetrain torque passes through the differential. As a result, the locking behaviour changes depending on whether the vehicle is accelerating or decelerating.
This allows the locking behaviour of the differential to change depending on whether the vehicle is accelerating or decelerating.
Understanding how ramp rider LSDs work is important when selecting the correct differential setup for a vehicle.
How Ramp Rider LSDs Work
Inside a ramp-style LSD are several key components:
- Clutch packs
- Pressure rings
- Ramp surfaces
- Side gears
- Differential carrier
When drivetrain torque passes through the differential, the side gears push against the ramp surfaces inside the pressure rings. As the side gears move up the ramps, they force the pressure rings outward and compress the clutch packs. Consequently, friction develops between the clutch plates and limits the speed difference between the two wheels.
The angle of the ramps determines how aggressively the LSD locks. Therefore, steeper ramp angles apply more force to the clutch packs and increase the locking effect. Additionally, motorsport teams can customise ramp angles to suit the driver’s requirements or vehicle setup.
1 Way LSD
A 1 Way LSD provides locking action only during acceleration.
When the vehicle is under power, the ramps apply pressure to the clutch packs and the differential begins to lock.
During deceleration or braking, the ramps do not apply pressure to the clutch packs. Instead, the differential behaves more like an open differential. Because of this, many manufacturers use 1 Way LSD units in front differentials.
1.5 Way LSD
A 1.5 Way LSD locks fully under acceleration. However, it provides partial locking during deceleration.
Manufacturers achieve this by using different ramp angles on the acceleration and deceleration sides of the pressure rings.
Therefore, 1.5 Way LSDs are extremely popular in street performance and track-day vehicles such as:
- Rear-wheel drive performance cars
- Street performance builds
- Track day vehicles
2 Way LSD
A 2 Way LSD provides equal locking force during both acceleration and deceleration.
Because the LSD locks under braking as well as acceleration, the differential provides strong and predictable behaviour when entering corners. As a result, many competitors choose 2 Way LSDs for drifting and rallying.
2 Way LSDs are commonly used in:
- Drift cars
- Rally cars
- Motorsport applications
Adjustable Ramp Configurations
Many aftermarket ramp rider LSD units feature multiple ramp positions on the ramp hubs.
By changing the ramp position during assembly, technicians can alter the locking behaviour to suit different driving styles or applications.
Clutch Plate Configuration (Stacking)
Inside the LSD clutch pack there are two types of plates:
- Internal plates which locate into the side gears
- External plates which locate into the differential carrier
By changing how the internal and external plates are stacked, technicians can adjust the effective locking percentage of the differential.
Standard Alternating Plate Configuration (Maximum Lock)
Most manufacturers supply aftermarket ramp rider LSD units with a standard alternating plate stack.
Internal – External – Internal – External – Internal – External
(I – E – I – E – I – E)
This configuration provides maximum lock. Therefore, it represents the most aggressive setup available in a clutch-type LSD.
Double-Stacked Plate Configuration (Reduced Lock)
Double stacking places two plates of the same type together. Consequently, the number of active friction surfaces decreases and the LSD engages more smoothly:
Internal – Internal – External – External – Internal – Internal – External
(I – I – E – E – I – I – E)
Furthermore, different plate arrangements can progressively change the amount of lock. The number of clutch plates inside the LSD also affects how much adjustment is available.
LSD Setup and Servicing
Proper setup is critical for achieving the correct behaviour from a ramp rider LSD. Therefore, servicing often includes preload adjustment, clutch plate inspection, and replacement of worn components.
Servicing may involve:
- Adjusting clutch plate configuration
- Setting preload
- Replacing worn clutch plates
- Inspecting internal components
At Gearhead Diffs, we regularly install, service, and rebuild ramp-style limited slip differentials for performance vehicles and motorsport applications.
