RC Nightmare Community Blog

Proper Gear Mesh

Whether you run nitro or electric all that power from your engine/ motor needs to make its way down to the wheels. Gears form the transmission that accomplishes this task and having them properly meshed or set up can affect the performance of your truck.

In RC cars and trucks the two main gears for transmitting power from the motor are the pinion (clutch bell for nitros) and spur gears. The pinion is attached to the motor’s drive shaft. The spur is part of the transmission – it may be connected to several more gears before transmitting power to the wheels. A gear mesh refers to the way that the teeth from one gear engages with those from another gear.

If this mesh is incorrectly set, by being either too tight or too loose, you will not be able to get optimal performance from your vehicle and will contribute to premature wear of some components. If the pinion and spur gears are meshed too tightly they will not rotate freely due to the excess friction created. This friction causes the motor to have to work that much harder to get the vehicle moving. The net result is the motor will heat up quicker and so will the gears involved – potentially contributing to a shorter service life. On the other hand, if the gears are meshed too loosely, the pinion will have too much slack when starting up and can cause damage to either gear. Often the pinion is metallic and the spur is plastic so the part to wear out first is the spur. A worn gear will have its teeth rounded abnormally when compared to a new gear.

This premature wear can be prevented by ensuring that the gears are meshed properly. There are two ways I know of for gauging gear mesh: by feel/eye and by using a strip of paper. I don’t quite have the feeling/eyeballing technique down just yet – the results are too inconsistent when you consider that the motor can move when you go to tighten its mounting screws. The paper strip method works great and is simple to do…

Paper strip gear meshing

  • Cut a strip of copy paper about 1/2 inches wide and 3 inches long
  • With the spur gear in place and the motor mounted loosely, slide the slip of paper in between the two gears
  • Apply some force to the motor to get the pinion to mesh with the spur causing the paper to become creased
  • Tighten the motor’s mounting screws
  • Remove the slip of paper

When you remove the paper slip it should have crease marks from the gears and not be torn by them.

The pinion and spur gears should be properly meshed every time they are replaced. In addition, gear meshing should be done as part of a regular maintenance schedule since the mesh may become loose over time.

We should have a short video showing the gear meshing process posted before too long so check it out if you would like to see the process being done.

One thought on “Proper Gear Mesh

  1. batman says:

    great write up
    always check ur mesh

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