The Greddy cover has this cool baffle which helps preserve the ring gears pumping action to lubricate the pinion properly and helps reduce slosh during braking, cornering and acceleration.
The baffle bolts in like so. There is still plenty of space so gear oil can circulate from the sump extension to the rest of the diff.
We started by removing the stock rear cover and bolting on the Greddy part. We expected some trouble because the Greddy rear cover is actually designed for an S14. A S14 mounts the diff through two studs on the cover going into rubber bushings in the crossmember. The S13 has 4 bolts and bolts directly to the crossmember with no bushings. The reason why we are using an S14 part is that we could not find anything simular for an S13 belive it or not. GKTech used to make one but it isn’t listed anymore so it’s probably discontinued.
After careful measuring, we drilled two new holes in our crossmember for the S14 style mounting studs. Our crossmember was reinforced here when we welded in GKTech’s reinforcement kit so we were not worried about damaging the crossmember. If you have a regular stock crossmember you might want to use some really large washers on the studs to spread the stress out more.
Our drilled crossmember fit perfectly. The extended sump cleared the crossmember well and our pinion angle was perfect.