Hubs – Free up the bearings

The 10mm bearings in the hubs are another great spot to spend some time freeing up.  Start by reaming out the holes in the hubs that hold the bearings.  Then work on freeing up the bearings themselves.  If you have already read the articles about the diff bearings or the spur gear bearings, then these steps will feel very familiar.

You can adjust the size of the holes to a perfect 10mm using a reamer, hobby knife, sandpaper, or Dremel bit.  If you use a Dremel bit, just spin it gently with your fingers.  Don’t use a Dremel tool, since that will remove far too much material.

For this example, I chose to use a small Dremel bit that I spun gently using my fingers.

Slowly remove a little bit of material.  Then retest the fit with the bearing.  Your goal will be to have a bearing that falls out of the hub with nothing more than a light tap, or even just the gentle pull of gravity.  Continue to remove material until the bearing can fall out easily.  Be careful not to remove too much material.  You don’t want there to be any play between the bearing and the holder.

Repeat these steps for both bearing holes on each of the four plastic hub parts that hold bearing.  You need to make sure all eight bearing holes are perfect, so there is no binding on any of the 10mm hub bearings.

The next step is to focus on freeing up the bearings.  There are two reasons the stock bearings are slow.  One is the rubber seal and the other is the thick grease.

Start by removing both rubber seals from the bearings.

With the seals out, use a RPM Bearing Blaster and some Trinity Buggy Blast (electric motor spray) to flush all of the thick grease out of the bearings.

Place a few drops of thin bearing oil on the ball bearings.  Gently rotate the bearings to spread the oil evenly.

The next step I recommend is to modify the rubber seals, so the seals don’t drag on the bearing races.  If you plan to race outdoors, you’d be smart to skip this step.  Rubber seals are handy for protecting bearings when racing outside.  I only race indoors on carpet, so I don’t need the rubber to completely seal the bearings.

Remove a little bit of rubber material from the inside of the rubber seal.  This will increase the inner diameter so the rubber cannot seal against the inner bearing race.  Don’t modify the outside diameter of the seal.  You want the outside diameter to remain big enough to cause the rubber to catch on the bearing’s outer race.

When you are done, carefully insert the rubber seals back into the bearings.  Technically, the rubber parts will be more like rubber shields than rubber seals at this point in time.  This will allow the bearings to spin more freely.

I only install one rubber shield on each 10mm hub bearing.  I leave the other side of the bearing open.  When I do the final assembly step, I point the open side of the bearing toward the inside of the hub.  The hub seals the open side this way.  The rubber shield side faces the outside of the hub.

Remember, place the open side of the bearings toward the hub, so the hub can protect the bearings.

The last step is to assemble the hubs with the bearings installed.

Follow these steps carefully and you will definitely be able to free up your drive train, and that will lead to high top speeds.  Good luck.

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