By Joe Coconate
For anyone interested in building a 3 gear trans for their RB6 before Kyosho releases their own I have a few good photos of how I built mine. It may not be perfect but I run mine with a 6.5 Mod on carpet and have had no issues. You will be using the 3 gear rear motor case included in the kit for this mod.
The first photo shows whats going to end up being your left side of the 3 gear trans case. In the picture I have the original case on the left and the shaved down version on the right. The bosses just need to be Dremeled carefully flush with the case. Then trim the first step of plastic off where the top shaft perturbed.
The second photo again shows the original case with the modded version to the right. The hole where the top shaft was originally needs to be blocked the from the inside of the trans case with approximately a 1.5mm or 2mm shim. I found that the plastic slipper spacer UM603B glued in with tire glue works perfectly.
The third photo is showing the top shaft. Unfortunately the top shaft has to be shimmed away from the bearing a little bit or the teeth of the gear chew into the case. I used just one plastic front axle spacer UM714 to keep it spinning free.
The fourth photo shows the right side of the trans case. A body reamer was used to make a hole where the top shaft will exit from.
The final photo shows the spacer UM508C and how I cut it into pieces to adapt to the new reverse orientation it will be in.
The cut up motor spacer supports the bearing and is still keyed into the motor plate. Next you need to shim the motor plate 6mm from the trans case. W0142GM spacers work really well here and match the color of all the other aluminum bits on the car. You need a lot of them, I used 20 total.
Tighten everything down and be sure everything spins smooth and free.
I was lucky to find a gear cover that is 3d printed and sold by a cool guy on Facebook.
Mount everything up in your buggy, hit the track and air it out!
What is better with this modification ?
Braking is increased tremendously. It jumps flatter, corners flatter and accelerated harder. You may lose some rear grip but it's not huge.
By Darren Wells
Spacer and end stop
End stop simply pushes into the non drive side of the gearbox.
Viewed here from the other side.
Drill a 10mm hole in the drive side of the gearbox.
Push in the spacer.
Cut the lugs off this part.
Build the gearbox up as normal. Adding the appropriate number of washers where the screws come through (I've ordered some black aluminium ones which haven't arrived yet).
