Use a thin strip of plastic to set the clearance
RC Model Gears
In RC there are a number of different gear teeth sizes we tend to use, based on two systems. Imperial and metric.
The imperial system has sizes 24dp, 32dp, 48dp and 64dp. DP stands for Diametral Pitch and the number refers to the number of teeth per inch.
The metric system has sizes 0.4m, 0.5m, 0.6m, 0.7m, 0.8m and 1m. M stands for Module and is the ratio of the reference diameter of the gear divided by the number of teeth.
The different sizes are used basically for strength. 32dp gear teeth are larger than 64dp gear teeth, therefore the 32dp gears are by design stronger and for this reason are more commonly used on a number of entry level buggys, to help them withstand the knocks and crashes by drivers new to RC, and nitro models because of the higher torque levels involved. Also, the bigger the scale of the model, the stronger the teeth need to be.
64dp and its metric equivalents are generally the choice of 1:10 electric on-road racers, because of its higher range of ratio options and smoother action in comparison to other sizes. On-road models are not as hard on the gears as off-road, so the weaker, small tooth size is not a problem.
48dp and its metric equivalents tend to be preferred by 1:10 off-road racers, mainly because of their strength in comparison to the 64dp and smoother operation than 32dp. Off-road models need gears that can handle all the knocks and bangs, as well as heavy landings off high jumps.
How to set Backlash between Gear Teeth
Setting your gears is the most important part of looking after your gears.
Backlash is basically the gap between the teeth in mesh. The perfect gear setting must have a small amount of backlash. To achieve the best setting use a very thin sheet of plastic between the pinion and spur gear teeth as you press them into mesh. After tightening the motor mount screws, use your fingers to spin the spur gear and roll out the plastic sheet.
If the setting is correct, there will be a small amount of movement (backlash) between the gear teeth before they catch. If the mesh is too deep, there will be no movement between the teeth, this will create friction and if you run them like this, they will grind together, wear and break. If the mesh is not deep enough and only the tips of the teeth are touching, the excessive backlash will soon damage and strip the tops off the teeth rendering the gears useless.
For More Setup Information check out my Hints and Tips page.