Associated RC10 Project

Page 1: Assembly

A close look at the box reveals that photo does not actually show the re-released RC10 Classic, rather it shows the original buggy. There are several clues, but the shocks in particular are a giveaway. It is also interesting to note that this buggy from an American company has a packing list which does not appear to be entirely in English.

Inside the box are a series of bags labeled A-J which each correspond to a logical sub-assembly of the model rather than to a specific step in the instructions. The right hand image shows everything arrayed on the table including the beautiful formed aluminum gold anodized chassis tub.

Despite the fact that this kit was clearly produced in China, one very strange aspect of it's design is that the parts are not metric, they use Imperial units. All of my build tools are metric so I had to actually use the array of tools shown on the left which came with the kit. The rhomboid part is a camber gauge. The open end wrenches are used for the shocks, and there is even a special tool to pre-stage the o-rings. The picture on the right compares the tiniest hex key to a standard cross wrench for scale. I think it is only 1/32 inch.

Construction begins with the aluminum chassis plate shown on the left which appears to be formed from 0.063" sheet metal. The picture on the right shows the attachment of the front chassis extension which connects with very unusual 8-32 aluminum screws. For those of you who are Imperial challenged, a #8 machine screw has a nominal diameter 0.164" (~4.2mm) and these have a fine pitch of 32 threads per inch. Aluminum strips very easily so these need to be installed with care. I can't think of a good reason to use aluminum hardware here except to keep weight down.

Let's get started on the front suspension. Nearly all of the plastic parts in the model are polyamide 6/6 (Nylon) which has a creamy white color but can be easily dyed to any other color. On the left you can see the 15 degree caster block supporting the steering knuckle which is attached with a kingpin secured with E-clips at each end. Imperial E-clips. Luckily they were close enough to a metric size that I was able to install them with my usual 3mm tool. On the right the steering uprights have been attached to the lower suspension arms with longitudinal hinge pins.

The left picture shows the steering cranks which pivot on shafts attached to the chassis plate. They have no upper support. The nuts are plastic to avoid over tightening and ensure free motion. The servo saver works by deforming the oval slot in the left hand crank. The right hand picture shows the front shock tower which appears to be G10 fiberglass.

Now the previously built shock tower and front lower suspension modules can be attached to the chassis plate as shown. Even though the front suspension is not really complete, the assembly is halted at this point so we can move on to the gearbox.

The gearbox is not quite like anything I've built before. We start with the drive gear pin shown on the left. If you look closely, you can see a roll pin which is inserted radially and fits into a slot in the spine plate. On the right this has been installed along with an idler gear pin.

The kit comes with solid bushings rather than roller bearings so those had to go. The wide flanged bushing shown at the left doesn't have a direct roller replacement so a stack-up of two bearings is substituted as shown. Again, these bearings use Imperial units. The bearings are installed in the steel drive gear using an internal snap ring as shown. Good look installing it if you don't have a dedicated snap ring pliers.

Two identical drive gears are built and then installed on opposite sides on the spine plate as shown. The drive cups are integral to the gears. The use of independent gears allows the two sides to rotate at different speeds. These will need to be connected through a differential.

Next we build two independent idler gears using screws and flanged bearings as shown. Every gear pair consists of one side metal and one plastic which obviates the need for additional grease lubrication. The color of these plastic gears leads me to suspect that they may be oil impregnated for long life.

The ball differential will be built into the spur gear shaft. The small pinion gear at the far left is locked to the shaft. The spool on the far right of the same image has a tapered end which is pressed into the other pinion gear. On the right the two drive pinions are assembled together on the shaft with a thrust bearing between them. This allows them to be clamped together tightly but still rotate independently.

The 1/8" balls for the differential are inserted into the 81T spur gear as shown. Once the assembly is greased, hardened drive rings are installed on either side and then the whole thing is clamped on the diff shaft using a compression spring as shown.

Now the transmission housing can be attached to the motor plate with the spine plate as shown on the left. There are 3 gears on the left and 3 gears on the right of the transmission, connected only through the ball differential. The diff adjustment screw is seen from the other side on the right.

A large rear bulkhead is used to attach the shock tower as well as support the installation of the gearbox as shown. Note the 9 different holes available for the ball joint which will support the upper suspension arm. The upper-inner position is used by default. Though you can't see it in the picture, each drive cup is surrounded by a felt seal to keep out dust and debris which is then captured with a plastic retainer.

Now the lower rear suspension arm are installed along with the upright hubs. Standard dog bones are used as drive axles. The upper suspension arms are called "turnbuckles" in the instructions but they are not true turnbuckles (which have a reverse thread on one end), they are just threaded rods. This means they must be disconnected to be adjusted. The camber can be adjusted by changing the length of the links, and the inboard position of each link attachment can also be moved to multiple possible locations. We've now completed the suspension assemblies at all four corners of the chassis. The rectangular slot just ahead of the rear suspension is used to center the battery.

While the aluminum shocks may look conventional from the outside, the assembly method is quite unusual. The rod end of the cylinder does not have a cap for encasing the seals. Instead, the seals insert from the head end. We start by assembling the a stack of two o-ring seals, a rod guide, some spacers, and a square retainer clip on the included tool as shown on the left. Using this tool, the whole stock is inserted into the cylinder until it snaps into place as shown on the right. Removing these parts for repair would be quite difficult.

The picture on the left shows a complete exploded view of an entire rear shock assembly. The picture on the right shows how a pair of plastic tools included in the kit are used to tighten the head end cap.

The completed front and rear shocks are shown on the left. The upper spring guides are not threaded to the shock cylinder. Instead, they are just clamped in place with a cap screw and held with friction. The completed installation is shown on the right.

The reproduction tires included in the kit are made by Proline of a soft, durable compound. The wheels are a 3-piece beadlock type. The rear tires are wide and spiked while the front are narrow and grooved.

I installed a temporary silver can motor while I waited for something more suitable to arrive. The protective gear cover is clear to show off the gear set. The kit did not include a pinion so I chose an 18T 48p pinion from Robinson Racing. The kit accepts pinions from 18 to 27 teeth. I used the smallest pinion because I intend to use a fairly hot motor, a Reedy 19T Super Stock.

I'd like to highlight one bad design feature which I circumvented. The travel of the front suspension is very small because the large spring perch hits the side of the pocket in the lower suspension arm as shown on the left. On the right, I've inserted one of the black spacers shown to put some space between the rod end and the spring perch. This totally solved the problem and doubled the suspension travel.

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