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By rotating the adjustment bolt, the preload on the clutch packs can be adjusted with this device built into the cross shaft assembly. This allows you to adjust the initial break away torque on the Nismo GT diff. You can see from left, the maximum preload, medium preload and minimum preload. We set up the diff in the medium position.
On most limited slips you can adjust the initial break away torque or the amount of torque it takes to get the wheels to move separately by installing shims to increase the preload on the differential’s clutches. On the Nismo GT unit, you simply remove the driver’s side axle and insert a socket into the diff and turn an adjuster inside the diff. Clockwise increases the initial breakaway torque and counter clockwise reduces it. There are 3 positions to choose from. Turning the adjuster moves a cam on the adjusting device which is built into the spider gear cross shaft and forces a ring against the clutches, preloading them more or less depending on how much you turn the adjuster.
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| You can see the preload adjuster nut here. Also note the 1.5 way and one way cam shapes on the ends of the cross shafts. THe Nismo GT diff has so much adjustment flexability. |
Adjusting the preload has a lot to do with how easily the car will lock the diff and get sideways when the throttle is applied. Full stiff and the clutches locks easily and the car squirts sideways. Looser and lock up is delayed and you can get more forward traction. For drifting, gymkhana and autocross you want the clutches with a lot of preload but for road racing you want them with minimal preload. On Sera’s car we set our adjuster in the middle since she does both track driving and drifting.
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| The adjuster nut in the housing. To adjust when in the car simply use a socket and extension. |
The rest of the Nismo diff is a fairly conventional Salisbury style limited slip. A Salisbury diff works using the cross shafts that hold the differential’s spider gears as a camming device to increase the amount of clamping load on the clutches. One axle’s end gear engages one set of clutch plates and the other meshes with the plates on the opposite side of the diff. If the axles are to turn against each other, the clutches must slip against each other.
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| Getting the clutches back in the diff case is a bitch! |
