Archive for the ‘Drivetrain’ Category

Hubs – Free up the bearings

Tuesday, January 4th, 2011

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.

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Diffs – Free up the bearings

Saturday, January 1st, 2011

The large 15mm bearings that hold the differentials in place are another great spot to spend some time freeing up.  There are two issues to work on.  One is the plastic part that holds the bearing has a hole that is a bit too small for the bearing, creating a binding effect between the holder and the bearing.  The other issue is the bearing itself.  The 15mm bearings are rubber sealed and full of thick grease, and that means a slower spinning bearing.  With a little bit of work, these issues can be cleared up.

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Bearings in Spur Gear Assembly

Thursday, December 23rd, 2010

One of the critical performance (and often overlooked) issues in modern RC touring cars is bearing drag.  When most RC industry companies design RC cars, they design the plastic parts without regard for plastic shrinkage.  When plastics cool after injection molding, the plastic parts tend to shrink slightly.

For example, if a company designs an 8mm hole to fit an 8mm bearing, the hole will actually be smaller than 8mm.  It won’t be a lot smaller, but it will be small enough that it will press too much on the bearing and cause the bearing to drag internally.  For example, the AE spur gear assembly was clearly designed for 8mm bearings but the holes are actually only 7.97mm.  If the bearings are simply forced into the undersized hole, the bearings will not spin as freely as they should because the plastic is actually slightly crushing the outside of the bearings.

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CVD/CVA Building Tips

Tuesday, December 14th, 2010

The CVD axles are often overlooked as a place to invest some additional time sanding and polishing.  If you build your CVD using the instructions from the kit, the CVD will work fine, but you will be leaving some performance on the table.  A little fine sanding with 2000 grit sand paper can reduce the friction in the CVD joints, which can result in a faster car.

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CVD – Wrong Size Hole in Part

Sunday, December 12th, 2010

One of the CVD axels that came with my kit has the wrong size hole drilled into it.  I am stopping my build to contact Associated about it.  Here are some pictures.

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Diff Building Tip

Sunday, December 12th, 2010

When building the differentials in the car, it is important to scuff the surface of the diff rings with 600 grit sand paper.  This will make it easier for the diff balls to grab.  You will be able to run the diff looser without it slipping.

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