|Last we bolted the diff end cover down.|
|Howard Watanabe of Technosquare first installed the ring gear on the diff using an angular torque method. He first torqued the ring gear bolts to a base torque, then marked them.|
|He then turned them 30 more degrees to the final tightness.|
We WPC treated the clutch plates as well. WPC treatment really makes a huge difference in how an LSD works. It makes the diff really smooth and quiet. Typically mechanical LSD’s clutches shudder and drag the inside wheel. It is very annoying on a street car and the rough jerky action reduces forward bite. Our prior experience with the Nismo GT diff was that it was a pretty rough differential. The WPC will make it smoother, quieter and cooler running.
|Next Howard set the pinion depth and backlash. The differential is first bolted into the differential case.|
|Then the play between the ring gear and pinion gear is checked for backlash spec. If it is out of spec, it is adjusted with select fit shims under the bearing races.|
|When the backlash is correct, the pinion depth is also checked. First the ring gear is marked with white lead. Grease can also be used.|
|The gear is then spun around and the area where the pinion gear is meshing the ring gear is checked. You want the contact area to be slightly low but mostly in the middle like this. You want the contact to be in the middle of the tooth radially and axially. Get this wrong and your gears will whine. This setting is adjusted with select fit shims under the pinion bearing. On street cars slightly low like this is better because as the gear wears the contact patch will move up. On a race car, in the middle is the best.|
Howard Watanabe of Technosquare installed our diff which is a somewhat tricky job that should be left to the pros. We filled the diff case with Motul Gear Competition 75w140 synthetic gear oil. This is extremely heavy duty synthetic gear oil which is temperature resistant. This is important as the diff on a 350Z tends to run very hot. In fact it is advisable not to run the diff hard for more than 20 minutes at a time on the track without a tranny cooler. Sera is going to monitor temps and report to us how much the WPC reduced temps and we can see if we are going to need to install a cooler later.
|Most 4 pinion LSD’s require new stub shafts that are shorter to make room for the pinion cross shaft. Nismo diffs come with these.|
|We used Motul Gear 75W140 synthetic gear oil because 350Z diffs tend to run hot.|
|Howard does the final touches to our diff install.|
When driving the car we were amazed at how much the WPC treatment really helped the diffs everyday driveability. The diff was nearly as smooth as a viscous diff with hardly any noise or perceptible jerking. Only when doing full lock U turns did it make any noise or wheel drag. When applying the throttle when turning, the locking action is very smooth and the car is easy to feel where the sliding point would be. WPC treatment really transformed the diff. We would highly recommend WPC treating any clutch type LSD’s. It’s way better than additive!
In our next installments of Project 350Z we will start looking at wheel and tire options as well as suspension stuff.