Demon Project

Page 1: Building the Chassis

This is the box that lured me in and gave me no choice but to purchase. It is big and heavy and has all the right boxes ticked. Almost all of the chassis is metal and there is a fully detailed hard body. Inside you can see a pile of plastic parts trees for the body along with an internal box which contains most of the chassis parts and hardware.

There are far too many parts to put on the table at once, so I've started by pulling out just the parts for the chassis. Since the axles and transmission are pre-built, there actually aren't that many parts. Note the lovely and heavy metal beadlock wheels. The GRU (Gear Reduction Unit) is a gearbox assembly which was already built, but I tore it apart both to make sure it was greased and to see how it worked. Based on the shape I assumed it was a planetary gear set but it isn't. Inside are multiple stages of tiny steel gears. I admit I was quite worried that these would not be able to stand up to the torque of my intended power system, but no problems so far.

The gearbox comes in the kit as shown on the left with a brushed 35 turn motor attached. Although I've found Cross' brushed motors to be quite good, I wanted to try something different for this model. The new Hobbywing AXE brushless motor on the right is what I chose. This system is specifically designed for crawlers to be ultra smooth at low RPM. The motor wires coming out the side of the end bell ended up being a problem.

I also opened up the transfer case to see what was inside. The housing appears to be cast aluminum and the gears are steel. You'll notice there are two inputs and two outputs which is one too many. This allows you, if you choose, to have the front and rear driveshafts rotating in opposite directions to reduce torque roll. Based on my experience and comparing to my other solid axle trucks, it works pretty well. Of course if you do decide to reverse the rear drive shaft then you also have to flip the differential or your rear wheels will be going backwards.

The main frame begins by connecting the two formed frame rails together with cross members. The center cross member will be the transfer case mount. The steel sliders are also installed at this point. The right hand image shows the biggest cross members which are actually integrated with the large inner fenders. I am really happy to see these since trucks look so much better when you can't see inside looking behind the wheel. Bumpers are usually installed at the end, but here they are installed at the beginning. They are chrome plastic.

Next to build are the shock absorbers. These are nice aluminum units with coilover springs and threaded bodies for adjustment. The bore is small so they don't offer a huge amount of damping, but they look good from a scale point of view and not much damping is required for a crawler. I really like how soft they are which allows for very realistic inertial motion of the vehicle over rough ground.

The axles are already assembled in the kit which is a little sad to me because I like building them. I tore them apart to see how they go together and added a bit of extra grease. Everything you see here is metal from the axle housings to the diff cover.

The 4 metal suspension links have been added to the front axle along with the servo mount, the shocks, and the steering rods. You can see in the left hand image that the knuckles provide a good steering lock. On the right I've installed the front axle to the frame.

The rear suspension goes together much the same way but without the steering servo. The right hand image shows the completed chassis from the bottom.

Now I've installed the gearbox, the transfer case, and the electronics. Note that the motor and gearbox are installed on an incline. There is very little room for the ESC and I happened to choose a huge one which made installation very difficult. The location you see here turned out to be a problem and had to be revised several times to get the faux engine to fit over the top. On the right you can see the rear battery tray which will sit under the floor in the back of the truck.

The beadlock wheels are incredibly heavy which leads me to believe either that they are steel or are very thick. The included foams are two stage with a hard memory foam inner and a soft outer. This allows them to retain shape even with a high weight but also to conform to rocks when climbing. Only 5 screws are needed to clamp the beads. This completes the rolling chassis and the model can now be driven.

There is still a lot of work to do to install the 100+ parts that comprise the body, but I can get an idea of what the final model will look like by dropping the largest part of the body shell onto the chassis. Looks real good.

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