Differentials – These are a key component to ensure your R/C is consistent and handling as it should be. After 2-3 Hours of run time it is a good idea to hold your R/C in the air and turn one tire to see how much resistance the differential has. If is feels like it has little to no resistance when you turn the one wheel it is a good idea to open up the differential and see what the fluid level is and how discoloured it is. When rebuilding a differential we recommend to take the outdrives, o-rings and the spider gears out to clean and inspect everything to ensure everything is in good condition. Once it is clean and inspected use some o-ring grease (Avid, Green Slime or 1UP Racing), on the o-rings and install them into the diff cup and ring gear. Use some grease (Hudy White, Protek premium white grease or Mugen super joint grease), on the outdrive to give some lubrication to the shaft of the outdrive going through the diff cup and ring gear. Install the spider gears on the diff pins and ensure they spin freely on the diff pins, install all 4 back into the diff cup and choose the silicone oil weight that you want to fill up the diff cup, some manufactures are using a weight of diff oil to ensure repeatability of fluid installed into the diff, please refer to your manual if you’re not certain. If you are not sure what diff oil is stock or we recommend please refer to the “Racing Setups” page or “Manuals / Exploded Views” page to get the information needed. On most diffs we recommend to fill the oil to just under the tops of spider gears and let sit for 5-15 minutes depending on viscosity used to ensure all air bubbles are out of the diff. Install the ring gear on the diff cup and start all 4 screws that hold the ring gear onto the diff cup, tighten the screws in a cross pattern to ensure you get the ring gear seated on the diff cup square. Once tightened check the diff action to ensure it turns as it should, install the diff with bearings back into the clean bulkhead and add some grease (Cow R/C Udder Butter or any good synthetic grease), to the ring and pinion.