Team Associated RC8.2 Build – Part 2 – Differentials

The Build – Part 2
The differentials are one of the most overlooked part of any 1/8th scale car. They can be messy to deal with and a pain to remove and rebuild. Most people leave ’em and forget ’em. If They are a tremendous tuning aid, and can be the difference in making the main or winning it. Before building, do a little research at the track you will be running at to see what the fast guys are running and build to their specs.

Build Notes:
Building the diffs can get a bit messy. Have plenty of thrashed towels around (not your mom’s good stuff!) to clean up the mess.

Make sure to grease ALL of the o-rings well. Don’t be afraid to use it…there’s plenty there!

There are three different types of input cups included with the RC8.2 It is extremely important that these be assembled correctly. Take a moment and remove them, match them up to the pictures and set aside or mark them.

Take the diff housing and install the bearings, o-ring and outdrive. On the inside, apply a little grease to the outdrive shaft and install the clear o-ring and diff washers. I used pliers to install the diff washers. Just made it easier (and a little less messy).

Slide the outdrive pin through the hole in the outdrive. Lining the hole up with the grooves on the inside of the diff housing will make this easier.

Slide the sun gear over the outdrive shaft. The back of the sun gear must key into the pin you just installed. A properly installed sun gear will look like the picture.

Assemble two spider-gear assemblies. Note the direction of the gears and don’t forget the shims! Slide the first one into the diff housing, making sure the flat spot on the shaft is pointed up.

Slide the other spider assembly into the diff housing, making sure the flat spot on the shaft is pointing down. They two assemblies should key into each other.

Assemble the ring gear by installing the bearing, o-ring and outdrive. Flip it over and put a dab of grease on the outdrive, then slide the clear o-ring and two shims.

Like the opposite side, slide the pin in and install the sun gear, keying it to the pin.

Apply a dab of grease to the ring gear and install the diff gasket. Line the holes up in the gear and gasket. The grease helps keep the gasket in place.

Fill the diff housing with diff fluid, as close to the top as possible. Spin the outdrive (below the housing) to circulate the fluid. The fluid level should drop. Fill with a LITTLE more fluid, or just below the top of the housing.

Take the two halves of the differential and put them together. It’s best if you take the ring gear side and place it on top of the housing. Line up the screw holes.

Screw the two halves together. You will force a slight bit of fluid out of the diffs…this is normal. Wipe clean and set aside. I like to mark my diffs with a F (for Front) and R and the weight of fluid is in them. This way, when it comes time to build or rebuild, I know what is currently in them. You can follow these same steps to build the center differential, too.

Part 3 – Assembling the front bulkhead.
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