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Torsen Rear LSD

PPG's torsen limited slip diffs provide smooth progressive torque transfer to maximize traction under varying surface conditions and weight transfers. Adjustable for pre-load depending on the application. Ideal for use on tarmac applications such as time attack, trackday, drag racing, gymkhana, etc. Relatively low noise and maintenance requirements when compared to clutch type limited slips.

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Manufacturer: PPG

Applications:

  • Subaru

Do these LSD's require special fluids? The LSD manufacturers recommend a GL-4/GL-5 gear oil of high quality. However, there are no specific friction modifier requirements for smooth operation like there normally is with a clutch type LSD. Any compatible gear oil for the Subaru will be fine.

How do gear type LSD's compare to clutch type LSD's? The gear type LSD is a maintenance free item that will maintain a consistent torque bias ratio for the life of the unit. However, because the bias ratio is a multiple of the torque available at the low traction wheel, if the wheel is off the ground then no torque can be biased to the high traction wheel resulting in a total loss of forward traction from that end of the car. A clutch type LSD will lose some of its torque bias ratio as the clutch plates wear, however, it can be tuned to provide a very aggressive lock ratio. Its initial torque also allows it to transfer torque even with one wheel completely off the ground. Gear type LSD's are relatively noise free whereas friction plate chatter is normal with a clutch type LSD.

How does PPG's "Torson" LSD compare to Subaru's factory Torsen® and helical LSD's? Special belleville friction washers are used on PPG's units to provide preload and therefore some small initial torque. Additionally, PPG units are set up with greater torque bias ratios as fitting a motorsport application.