Project NSX: Part 2 – Tuning a Limited Slip Differential

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Next one side of the clutch discs are loaded into the case.  The tabs on the driven clutch discs are set into the slots in the diff case.
Next the first bevel gear is slipped in place, meshing with the driven clutch discs.

The pressure ring and spider gear assembly is dropped in and the the rest of the clutch discs are installed and then the other beval gear is installed.

 As a final step we sent out our clutch discs to get WPC treated. To read more about WPC Treatment , click here! Many mechanical LSD’s are noisy; they ratchet and chirp the tires on sharp low speed turns. The diff is locking here and doing its job at low speeds. When adjusted aggressively they skid the inside tire and shake the whole car. Special LSD additives reduce this NVH nightmare but often cannot eliminate it. By WPC treating the clutch discs, it is possible not only to eliminate this irritation but to also improve performance by shocking the tires less to so they can find traction better.

The OS Giken LSD has some of the smoothest operation of any aftermarket LSD we have tested with minimal to no noticeable ‘chattering’ side effects. Due to the special properties of WPC treatment, we chose to WPC treat our LSD since the treatment often results in the discs lasting 2X longer and cooler as well. If you drift which is really hard on LSD clutches, this treatment can really help. On a street car it’s almost mandatory for the smoothness it provides. WPC works so well that Kaaz offers it as an OEM option.

The case half’s are bolted together then the ring gear is bolted on with red loctite.
Steve Mitchell gives the head of each ring gear bolt a firm rap with a big ball peen hammer and a center punch.  This releases tension on the bolts and allows them to be retorqued again more accurately.  Hit the bolt head, then retorque.  You will see the bolt turn a little more before the torque wrench clicks.

As we said, most of these tricks can be applied to any aftermarket LSD and they make a big difference, especially for grip driving. Now that we have gotten our transaxle together, we will focus on our engine in future installments of project NSX.

Sources:

OS Giken

WPC Treatment

FX Motorsports Development

Steve Mitchell

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