GCM Racing RB3 Buildup - A racer from the start.
This article will go through the entire build process of a fully equipped RB3 using the finest components. Links will take you to vendor pages where you can find more information on the parts used in the build.
Step 1: The first operation we will do is to prepare the powerplant and center gearbox. We start off with a E-Savage Center Gearbox and a modified motor plate that now holds only one motor. The motor plate can be installed on either side, and depending on the location of your motor wires, this can be handy. You want to mount your motor to have the wires opposite the gearbox, or on the outside of the chassis. This will give you the most clearance for the batteries.
Step 2: Install the clutch assembly on the spur shaft now. Your clutch installation will be easiest to do now while the gearbox is out of the chassis. We are using the Friction Clutch Conversion from GCM Racing for our build.
Step 3: Find the right side plate, and the lower and front battery tray parts from the RB3 kit. Use the hardware shown to assemble these parts, and do not make the screws too tight! As a rule, we like to assemble the parts to a close fit and then add no more than 1/3 turn on the screw. The front battery tray part will have a slot that fits on the lower battery tray in the center. The screw holes are offset also in the front tray part in order to make sure everything is assembled the right way. Remember: the lower tray part fits into the slot in the front tray part.
Step 4: Assemble the servo mounts next, using the hardware sizes shown. Remember to use medium threadlocker when shown. You don't want loose parts later and have to take things apart. The upper steering brace will also be installed at this time.
Step 5: Now mount your completed center gearbox onto the right side chassis plate. You can see now why it is easier to install the clutch assembly before this step.
Step 6: We will prepare the steering components now. We are using the E-Savage steering bellcranks from HPI and have reversed the servo horn and installed the required Super Glide steering kit from Panic Toys. Install the servo linkage in this step also (not shown). The finished steering assembly will be installed under the top steering brace from step 4 using (2) M3x8 screws and the lower steering and chassis brace also installed with (1) M4x10 screw under the servo mount.
Step 7: Install the remainder of the Superglide kit with the servo mounting screws and captive washers. We will leave the servo horn for later in the setup procedures.
Step 8: We will now prepare the differential gearboxes for use in the RB3. We will be using the E-Savage Differential Assembly from HPI, and re-fitting them with the TWIN Differential Conversion from GCM Racing. Perform each of these operations to the front and rear units.
Open up the differential unit to expose the stock conponents. You will notice the ring gear is on the right side. We will remove the tab from the housing and install the TWIN differential with the ring gear on the LEFT side now. This is necessary because the center gearbox is reverse-facing in the RB3 platform, and will allow us to run the motor in the original counter-clockwise direction. While working on the housings, put on the 3 pin braces for the suspension pins.
Step 9: Add the drive cups to the front, rear, and center gearboxes.
Step 10: Fit the differential housings on to the right side chassis plate using one screw in the top hole. While fitting these to the assembly, place the front and rear dogbones into the drive cups.
Step 11: The rear chassis brace can now be installed with one M4x10 screw. Do not tighten this screw until later.
Step 12: Place the left side chassis plate on the assembly, using the same hardware sizes shown for the right side plate. Remember to tighten screws into the plastic parts only until the head of the screw touches the metal side plate. Do not crank screws tight that are threaded into plastic parts.
Step 13: Assemble the lower and upper suspension arms with the differential cases and the C-hub steering parts. Begin with the lower arms, then the C-hubs, then the drive axles, and finally the upper suspension arms. We are using the RacerEX Suspension from GCM Racing for our build.
Step 14: Install the rear track rods. We used the Bumpsteer Bracket from GCM Racing and then used trackrods with a center-to-center dimension of ____mm. We mounted the trackrods under the steering knuckle on all corners, and mounted the Bumpsteer bracket in the 'UP' position. This offers a slight toe-out condition on hard braking and almost no change in toe from center to full compression with our setup.
Step 15: Install the lower skid plates and covers using 2 M3x8 for the plate-to-diffs, 2 M3x10 for the chassis braces, and 4 flathead screws for the plastic covers. Then clip in the top bumper posts onto the shock tower. We always clip off the back section of the rear skidplate to clear some room for adjustments.
Step 16: Install the shocks on the truck. We like to use the HPI Aluminum Shock Set and use 35 weight Associated Silicone shock oil. This great shock works perfectly on this truck with the HPI Black Spring Set and only 4 shocks on the truck. If you want to use the white springs that come with the shocks, then we recommend using all 8 shocks and 30 weight oil. Be sure to only tighten the screw into the lower arm until it is touching the side of the arm. Do not tighten this screw all the way down, or you will bend the outside part of the shock mount. Even though this part will spring back, it is not necessary to put the screw in that far.
Your build should look like this now. A completed platform ready for electrics and wheels.
After installing all your electronics and power system, be sure to check over the entire build for loose hardware. Note also that the metal dogbones do produce a small amount of 'chatter' when coasting. If this is undesireable, set up your ESC to have a small amount of drag brake, and this will be eliminated.
Now go racing!
Here's a short video of what you can expect from your new build as shown in this article.