Tamiya FF-03 Project

Page 3: FF-03 EVO

The EVO is the model I actually wanted to build when I started this project. All the other variants just came along with the purchase. I consider the EVO to be the ultimate incarnation of the FF-03 (although the upgrade kit is a close second). I started by building the EVO in a completely stock configuration which is what I am documenting here.

The model arrived assembled so I started by completely stripping it down to kit form as shown. There actually aren't very many parts in this chassis given that it has only one gearbox and differential, and very little of it is plastic. Carbon fiber and anodized aluminum are well represented here.

Unlike the standard variants of the FF-03, the EVO uses a sealed gear differential instead of a ball differential. The internal gears, including the 4 spider gears, are all reinforced plastic. The drive cups are sealed with o-rings and then the housing is filled with extremely thick #100000 silicone oil that appears to be unique to FWD models. This viscous fluid resists, but allows, differential motion of the axles.

Here is the completed differential along with the other components of the gearbox. The spur gear shaft appears to be hard anodized aluminum with an integral gear for minimum rotating inertia. The idler gear is plastic and rides on a blue anodized aluminum shaft. All rotating parts use special low friction fluorine coated sealed ball bearings.

Now the gears can be added to the reinforced gearbox housing as shown. The front upper arm mount has been added on the right along with the long aluminum ball connectors and aluminum spacers. All the parts on this kit are so nice.

The EVO uses an anodized aluminum motor mount with machined heat sink pockets and a carbon fiber motor stay. All of hardware is hex drive instead of JIS including the rare 3x48mm button head cap screws.

The spur gear mount is also aluminum but gets mostly hidden once the 68T 0.4 mod spur gear is installed. The motor sits ahead of the axle for maximum weight over the front wheels.

The bracket for the inboard front suspension is machined, anodized aluminum and supports the pivots for the suspension cranks. The cranks are plastic but each use 2 additional aluminum ball ends and spacers. All of the front suspension forces pass through this assembly which will also serve as the attachment for the carbon upper deck.

Adding the inboard front suspension mount assembly to the gearbox assembly completes the front end module. It doesn't look like much yet, but all of the suspension parts will connect to this.

The next assembly to build is the steering system. The dual bellcrank steering arms, steering bridge, and steering mount are all machined aluminum right out of the box. Every joint uses ball bearings and all the ball connectors are aluminum as well. It's all very smooth to operate.

Now we can finally start on the chassis backbone. The primary base plate is 2.5mm thick carbon fiber sheet. All of the holes on the bottom surface are countersunk for a completely smooth underside with no protrusions. First I've attached the aluminum steering posts and the plastic lower suspension mount as shown on the left. On the right I've added the steering crank assembly which comes very close to the suspension mount.

The lower reversible suspension arms can be flipped to make tiny changes to the locations of the shock mounting holes so care must be taken to be sure they are installed symmetrically. The spacers on either side of the arm pivots can be changed to make small adjustments to the wheelbase. Both suspension mounts are the same width (1XD) so there is no toe angle built into the front arms. The steering links use aluminum turnbuckles and have also been installed.

Now the gearbox has been installed on top of the lower suspension arms along with the plastic bumper support.

The EVO uses beautiful double cardan axles which have to be assembled from seven separate parts as shown. These allow a much larger steering lock with less chatter than a regular CVD. They are shown installed into the steering knuckles on the right.

Each steering knuckle can now be installed into a C-hub using a pair of flanged bushings to avoid clamping the joint. The completed front suspension is shown on the right. The upper suspension links use the same type of aluminum turnbuckles as the steering links. Camber is altered by adjusting the suspension links and toe is altered by adjusting the steering links. Note that the upper and lower suspension arms have different lengths which results in the camber increasing as a result of suspension compression.

The rear suspension goes together pretty much like the front using reversible arms, pivot pins with ball ends, and spacers. In this case the combination of a 1XD and 1A suspension mount results in a rear toe angle of 2.5º.

There is no rear gearbox or differential, so in this case the only purpose of the rear bulkhead is to support the massive 3mm thick carbon shock tower and upper suspension links. Even so we get these lovely machined parts. Note how only the lowest holes in the shock tower are used by default, so most of that width is unused in stock form.

Here the rear bulkhead has been attached to the chassis plate. This looks very, very different from the plastic rear suspension assembly of the standard FF-03. The rear shocks of the EVO will now be installed on the front side of the suspension arms instead of the rear side like the standard chassis.

The rear stub axles can now be installed into the uprights. The shims shown limit the lateral play in the axles and keep everything tight. On the right you can see the completed rear suspension using aluminum turnbuckle upper links. Also note the clamping aluminum hexes.

If the entire stiffness of the chassis were based on a 2.5mm carbon base plate with nothing between the front and rear bulkheads, it would be very flexible indeed. To counter this, a 2mm thick upper chassis plate is added to span the tops of the bulkheads. This completely alters the overall stiffness. This upper plate also serves as the support for the central aluminum shock mount shown.

Here are the beautiful TRF shocks that I've come to know and love. They are always a pleasure to build and operate as smooth as silk. These springs appear as black in photos from the Tamiya Japan web site but white in the North American site. They are otherwise identical to the shocks that come with the FF-03 PRO and R.

Installing the shocks in the front and rear completes the assembly of the suspension. The rear shocks are mounted in a traditional "vertical" manner, but are still angled quite significantly by default. Other holes are available in the shock tower to make them slightly more vertical. The front shocks are mounted in a longitudinal orientation which differs from the lateral orientation of the standard chassis. I'm not sure what the advantage of this configuration is.

The body posts are very tall! I can't imagine any touring car body that would require such a length, but it is nice to have the option.

Here I've installed a temporary motor and a 26T 0.6 mod steel pinion gear. A plastic cover is the installed over the pinion and spur to keep out dust and rocks.

The final details are the servo tray and high torque (but not aluminum) servo saver. I'll install the rest of the electronics after I install a bunch of upgrade parts.

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