Tamiya Mercedes G500 Project

Page 1: Building the Chassis

This very first CC-02 model comes in a box very similar in size to a typical CC-01, though somewhat deeper. That extra depth is to make room for the quite sizeable G500 body which is about all you can see when you open the box. Apart from the tires, everything else is packed beneath the body shell.

You can already tell this is not going to be a simple chassis based purely on the number of parts trees and hardware bags included. Most of the trees are black and only a couple are dark gray, but from what I can tell all are glass filled Nylon (example shown at right) for strength and stiffness.

The transmission uses 3 gears (2 pairs). The 2nd pair can be installed two ways. If the smaller gear is used as a driver, you get a gear reduction and a low speed ratio. If the larger gear is used as a driver, you get a gear increase and a high speed ratio. Since one of the major issues with the CC-01 was too high gearing, I used the low ratio as shown. Note that the kit came with plastic bushings but I immediately switched to ball bearings.

Directly tapping into glass filled plastic is not a great idea because it tends to be quite brittle and can crack. Wherever possible, Tamiya uses nuts instead. Many of them are installed in a strange manner. On the left, you can see a nut in a slot trapped by an overlapping washer in the transmission housing. The right hand image shows the sealed up gearbox with only the transfer case output protruding.

The kit uses a very large 83 tooth spur gear with 0.6 mod pitch. It seems like the disc attached to the spur could probably be replaced with a slipper clutch, but none is included nor does an optional slipper exist at the time of this writing.

Now the final covers can be attached to the transmission and the motor installed. The kit comes with a standard 27T silver can which is really still too fast for a crawler. I replaced the stock aluminum 16T pinion with a steel version. The aluminum pinion is shown sitting on the housing for comparison. Larger pinions up to 25T can be used, but nothing smaller.

Now we can start building the chassis which uses more glass filled parts. Here another way to support nuts is shown on the right. These square molded blocks hold nuts and are prevented from rotating by mating parts.

The chassis starts with the cross members, but these are much more than just I-beams or C-channels. There is a huge molded front part which will hold the gearbox, the servo, and the electronics. It is heavily braced and reinforced. The rear longitudinal battery tray attaches above and behind this and fits modern rectangular Li-Po batteries. On the right you can see that the molded plastic frame rails have been attached. Yes, they are plastic but because of the construction this is still an incredibly rigid chassis.

The plastic shock towers are attached to metal frame extensions as shown. Front and rear shock towers are the same and each feature 3 upper attach points. They also appear to be reversible to accommodate different wheelbases. The front frame extension houses the chassis mounted servo which can be installed either horizontally or vertically.

Once the extensions are installed we can see the full length of the ladder frame. Now the transmission can be installed using 4 screws from below. It is tricky to get the gearbox aligned. It has to be tipped, lowered, and then straightened out to fit.

The universal joints of the plastic drive shafts have to be assembled manually by deforming the yokes. This is pretty easy to do because the plastic is so soft. This same softness had me worried that they would pop apart under high torque, but I've had no problem so far. The male splined ends of the drive shafts are installed to the transfer case as shown.

The CC-02 uses exactly the same cast differential parts as the CC-01 which, as far as I can tell, is the only commonality between them. The version on the far left shows the stock open differential, while the version just to right shows how to lock the diff by inserting a plastic locker in place of the spider gears. I fully locked my build. The axle housing is significant and rigid. There should be no breakage here. The axles have dogbone ends, but universals are available as an upgrade.

Here's the beefy front axle all buttoned up on the left. On the right I've added the brackets for attaching the suspension links.

Now I can install the steering bits. The knuckles are one piece plastic with no caster. The steering link is plastic and not adjustable. The servo link is a metal rod with plastic rod ends and balls. In the photo on the right you can see the suspension links. Upper and lower links have different profiles but are all plastic with no adjustability.

The rear axle is just a simplified version of the front without steering. The differential is exactly the same, but the links are a different length.

The brackets shown are used to attach the links to the chassis, and this is where all the wheelbase adjustability comes in. You can see that there are an extra set of holes for each bracket. These are spaced at 10mm so they allow a shortening of the wheelbase by that amount. You can also see that the link attachments are not centered between the screws; they are actually offset by 5mm. This means you can swap them left to right for 5mm adjustments. The G-500 body uses a 267mm wheelbase, the second longest possible on this chassis. The full list of options are: 242mm, 247mm, 252mm, 257mm, 262mm, 267mm, and 272mm. Note that different length links and drive shafts would be required when changing wheelbase. There is very little triangulation in the suspension, so it is almost more like trailing arm than 4-link.

The gray oil shocks included are simplified CVAs with integrated pistons just like the CC-01, but with a longer stroke. All four corners use the same size. It is relatively unusual to see Tamiya include the red damper oil with a kit. This is the softest (least viscous) oil they make.

If you put on long enough shocks, you'd get a land strider look like this. U-joint angle might be a problem.

With the shocks installed the chassis is essentially complete. Note that the shock diameter is vastly too large for scale (as is the length), but this is a good thing for performance.

There is plenty of room to install the included TBLE-02s ESC and route the wires neatly as shown on the left. Installation of the wheels and tires completes the rolling chassis which is now fully driveable.

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