Axial SMT10 Project

Page 1: Chassis Assembly

Without giant tires or a body to take up space, this body is pretty small for a 1/10 scale monster truck. A set of wheels is included although I ended up using something different. The bags inside the box correspond to sections of the instructions.

Here is a terrible picture of some of the bags and the manual prepared on my building table.

The build starts with the axles. The front and rear axles are identical at the start which means the truck could be converted to four wheel steer with some extra parts. The differentials are open with 4 spider gears and are intended to be greased, not filled. They can be locked with an optional locker. Note the off center pumpkin and the fact that the differential ring gears are installed in opposite directions front and rear.

Now the front and rear axles start to be differentiated from each other. The front axle shafts use dog bone ends (upgradeable to universals) and the rear uses straight axle shafts as shown on the left. On the right you can see that the front axle got C-hubs installed while the rear just uses straight extensions with additional bearings. These are Axial AR66 axles, the same used on the Bomber.

now the trusses and link hangers have been installed as shown on the left. The same geometry is are used front and rear although the truss is mirrored. That completes the rear axle, but the front axle still needs the steering knuckles and links as shown on the right. The steering tie rod looks very complicated as though it has integrated shock absorption capability, but it really just a monolithic plastic part.

Now the links can be prepared. The lower links are trailing arm type and will connect to the shocks. These also effectively act as sliders. The upper links are triangulated and kinked. The kit only comes with plastic ball joints which I found a bit disappointing. The right hand picture shows the links, which are identical front and back, installed on the axles.

The included servo saver is pretty serious. You can see the 5 levels of steel ring springs shown on the left. On the right I've mounted the servo to the front axle. This is a temporary servo I was using until a matching Spektrum servo was back in stock.

The shocks are very long travel coilover type with aluminum cylinders. The kit comes with relatively thin 30wt oil. An exploded view of the shock is shown at left alongside a completed shock. All four are the same, but front and rear use different springs. Heavier springs are used in front. On the right you can see the shocks attached to the trailing arms.

Here is the old reliable Axial AX10 3-gear transmission that has been in use since the very beginning. The kit comes with nice sintered metal (not machined) gears and full ball bearings. The left hand picture shows the guts of the transmission prior to greasing. On the right I've closed it up and added the metal motor mount.

The plastic spur gear uses big 32p teeth and incorporates a slipper clutch with 2 pads. The compression coil spring shown on the right clamps the discs against the friction surfaces and regulates the amount of torque which can pass through the transmission before it slips.

Here I've installed a temporary brushed motor (55T) that I happened to have lying around. This will certainly not be what I end up using the vehicle, but it is enough to get started. The kit includes a 14T pinion gear and a 56T spur. On the right I've attached the gear cover. Note the central opening which allows access for adjusting the slipper.

Now I've bolted the transmission to the skid plate as shown. On the right I've started assembly of the drive shafts which are made up of quite a few parts. The far right is an exploded view. These are Axial's standard shafts which, despite being plastic, hold up very well. The highly stressed end joints are steel. Only the sliding splined shafts are plastic.

Th receiver box in attached to a cross member as shown. The box is quite spacious and more than enough for my Spektrum 2-channel receiver. A temporary brushed ESC is also shown installed. The right hand picture shows the battery box. The upper cage part is adjustable up and down for batteries of different thicknesses.

Now we get to the major structural parts, the chassis cage halves. The first one-piece half is shown on the left. Although I would have preferred to build this up out of many pieces, the monolithic design is stronger and cheaper. On the right I've added all the various cross members which will join the two halves.

Here is the second cage half has been secured in place completing the chassis. On the right I've attached the links and shocks to the chassis cage which is all that is needed to make this a usable rolling chassis.

The kits comes with a sway bar for the rear only as shown. This is intended to reduce body roll but I still had major issues as has been discussed elsewhere. I ended up adding a second sway bar to the front and greatly stiffening the shock springs.

Here I've added some test tires just to try out the chassis. As ridiculous as it looks, real monster trucks are trailered with tiny tires like these to keep them low enough to pass under bridges.

The picture on the left compares the large silver wheels which came with the kit to the much larger white wheels from JConcepts I decided to use instead. This choice had quite a few consequences on handling since this chassis was really made for the smaller tires with lower power. That means a lot of other modifications were in my future.

Up to Index | Go to Page 2