Stinger / Strut Outdrives
The outdrives are the most important part of the drive hardware. There are two types of outdrives that are commonly found on RC boats.
These include the Stinger outdrive and strut drive. Stinger drives are usually only found on mono hulls. They house the prop shaft completely from the transom to nearly the prop. This provides a unique appearance to the hull.
A strut setups is more commonly found on all hull types. This holds the prop shaft usually a set distance away from the transom.
Drive Dog / Prop Shaft
The drive dog is used on the prop shaft to transfer power from the prop shaft to the prop. There are different sizes for each shaft size. Select the one that works best. The distance between the drive dog and strut/stinger should be the thickness of the cable. If you are using a .187” size flex shaft keep the distance between the drive dog and strut/stinger to .187” or 3/16”
Flex cables shorten when under load. This set distance will allow the flex cable to shorten and not wreck havoc on the motor, strut or create extra drag from binding. Keep in mind this will never be seen on the bench, it only occurs when the boat is running in the water.
Flex Coupler/Thrust Bearing/Motor Mount.
This component couples the flex shaft to the motor shaft to transfer the power. Also known as Flex Hex. It is wise to place a thing coating of solder on to the flex shaft in the area the flex coupler will hold it. This maintains a nice snug grip while not separating the winds from the flex shaft. The coupler can easily be seen in the photo above. Directly behind the coupler is known as the thrust bearing. The thrust bearing takes the thrust from prop and directs it to the motor mount as seen in the photo. In other cases the thrust bearing can direct the power to the motor can itself. Depending on which motor mount is used will determine where the thrust from the prop will end up.
The flex cable delivers power from the motor to the prop shaft. It is flexible, hence the name, to allow power transfer in tighter spaces and mainly to allow the prop shaft to be close to parallel with the bottom of the hull. In order to achieve this the flex cable is bent with motor on an angle. Flex shafts come in 3 Main diameters.
0.125″ – For lower Power Setups
0.150″ – Mid Power Setups
0.187″ – Mid to High Power Setups
0.250″ – High Power Setups
The flex cable also comes in many different lengths. Therefore it’s required to cut the flex cable to the proper size. In order to cut the flex cable it is most beneficial to solder the cable first. This will prevent any unwinding during the cutting process. Once the section to be cut has been soldered, use a dremel or any other sufficient device to cut the cable. Be certain the flex cable is still tinned on the end after the cut. This way the flex coupler can grab the cable without crushing the cable.
The stuffing tube supports the flex cable shaft. It provides the shape the shaft will follow. It should be placed as close to the motor as possible and usually goes right inside the strut or stinger. The stuffing tube in some cases house a Teflon tube which also is used to support the flex cable.
The stuffing tube can be made out of K&S tubing with sizes as follows:
Stuffing tube Size when used with Teflon tubing
3/16″ tube for Octura .098 Teflon tubing.
7/32″ tube for Octura .130 Teflon tubing.
1/4″ tube for Octura .150 Teflon tubing.
9/32 tube for Octura .187 Teflon tubing.
11/32 tube for Octura .250 Teflon tubing.
Stuffing tube sizes when used with out Teflon tubing:
5/32″ tube for Octura .098 Flex Cable.
3/16″ tube for Octura .130 Flex Cable.
7/32″ tube for Octura .150 Flex Cable.
7/32″ tube for Octura .187 Flex Cable.