Overhaul kits for STI clutch type LSD's include cone springs, inner splined plates, and outer splined plates. There are a selection of plate thicknesses allowing some tuning of the initial torque setting.
Usually ships within 1 to 2 weeks
What is the best way to confirm the correct overhaul kit for my particular LSD? We have prepared a file to cross reference the LSD part numbers (STI and FHI) with the correct overhaul kit part number.
What is initial torque? Initial torque, also known as break-away torque, is a measure of the torque required to achieve relative motion between the two axle outputs of the LSD. It is dependent on the preload applied to the clutch plates. It can be increased or decreased by changing the spring rate of the initial torque springs. Additionally, changing the clutch plate thicknesses so that the stack height is increased or decreased (to compress the spring more or less) allows for fine tuning of the initial torque.
High initial torque values will reinforce the handling balance the drive torque at that end of the car provides. A high initial torque at the rear of the car will increase the tendency for oversteer while high initial torque at the front of the car will increase understeer. It will also reduce the throttle sensitivity provided by the pressure ring ramp angles.
What is included in the LSD overhaul kits? It depends on the particular LSD kit. Front and rear LSD kits generally include a full set of replacement clutch plates. Additionally, extra plates of varying thickness are supplied to allow for fine tuning the initial torque. Some kits are supplied with springs of higher rate (belleville spring washers of increased thickness). Center LSD (DCCD) kits are supplied with most of the internal parts and external bearings with the exception of the planetary gears and electromagnet.
How often is it necessary to rebuild an LSD? It depends on the type of application. As the clutch plates wear there will be a loss of initial torque and performance will suffer. The rebuild schedule will depend on how critical it is to maintain maximimum LSD performance.
Is the factory R180 clutch type LSD ready to be used in competition or does it require modification? The factory R180 clutch type LSD used on certain Impreza STI models is set up with very low initial torque in order to minimize noise. It will not be very effective in most competitive applications and will wear quickly due to high relative rotation between the friction surfaces. Rebuilding the LSD with RST-1951RK for higher initial torque will make the LSD more effective for a wide range of competition purposes. However, there will be a noticeable increase in noise due to stick-slip phenomenon while cornering with no or light throttle input. Careful oil selection can help reduce noise levels somewhat. Additionally fitment of the uprated pressure ring set will further improve motorsport performance by increasing diff locking relative to throttle input making the LSD more sensitive to throttle modulation.
