3. We then took our new measurements with everything installed on the differential. From driver side ring to race we measured 2.061 and the total width 7.722 inches. With these measurements, we were able to reuse the driver side shim, but we had to use other shims from our bearing kit because we had 10 thousandths of an inch less space on the passenger side. All of these measurements might vary depending on your car and year model.
1. Now that you have some rough measurements, you will now need to test fit your new differential. To do this, we installed the differential and put the caps on to see where we were at. This is probably the most time consuming part of the install because you want to make sure that everything fits properly. We had to do this about (3) times before we had the amount of backlash on the gears that we wanted without there being any space for the new differential to shift side to side. Our final measurement for our backlash was 10 thousandths of an inch.
2. Once you find the proper alignment, put Loctite on the bearing cover bolts and tighten everything up.
3. Push your axles back in and secure them with the old C-clips the same way you took the old ones out.
4. Next, install the old differential cover. Make sure to use plenty of gasket sealer if you do not have a new gasket so that it doesn’t leak. If using sealer, take some time to let it cure and dry for about an hour.
5. Next, fill the differential with 1.5L of 75w90 gear oil of your choice. We used Lucas Oil just out preference and had to add 3.5oz of friction modifier to prevent any noise and any excessive wear on the new parts.
6. Finally, reinstall your wheels and take your Mustang for a test drive. Listen and pay attention to anything that seems odd. Take some corners and do some tests to make sure both wheels are gripping the way they are supposed to. Enjoy your new 7.5” Limited Slip Differential!
Installation Instructions written by AmericanMuscle customer Zachary Meyer 4.2.12