So our project S13 came with a Nismo 1.5 way clutch type limited slip differential that the previous owner had installed. From prior experience we know that clutch type LSD’s tend to run pretty hot, particularly on road courses. We found they the gear oil starts to oxidize at 250 degrees and the differential itself can get too hot and sieze once the temperature gets to around 325 degrees. It is pretty possible to reach that temperature in 20 minutes or less on some courses. In drifting, a lot of stress is put on the diff but drift sessions are very short. We did not want the complication of running a diff cooler which requires a cooler, lines and a pump, we want to keep things simple so we opted for a Greddy large capacity back cover for our diff.
The Greddy back cover has an extension that holds an extra 900cc of gear oil or almost a quart. This nearly doubles the gear oil capacity of the differential.
Here you can see the extension that sticks out behind the cross member. The extension and the cover itself are covered with fins to help improve cooling.
The diff covers curved rear shape and vertical baffles help make sure that the ring and pinion have a constant supply of oil. It is pretty important to retain the features. For instance a squared off shape can reduces lubricant flow to the ring and pinion by more than half!