Tamiya Juggernaut 2 Project

Page 1: Restoration

Here is the Juggernaut 2 in the state I received it. The stickers have been applied but the body was never painted. There are some scratches, especially in the chrome, but mostly the body shell is in good condition. One of the tires has a big crack in the side wall but these irreplaceable tires otherwise look good. The chassis is a bit dusty but looks to have hardly ever been used. In fact, I was able to plug in a battery and use the truck with the original electronics and mechanical speed controller with no problem.

Here is a closer look at the original electronics. The resistor sits at the very front of the chassis. The 3-speed mechanical speed controller and throttle servo sit under a plastic cover behind that. There is a slot for a 4-AA battery pack for the radio, but the original builder used an Airtronics receiver with a built-in BEC so this was not needed. The original servos were Airtronics (Sanwa) as well, a fact which will become important later.

Here is the full electronics package removed from the vehicle. My original plan was to re-use the original silver can motors but replace pretty much every thing with modern electronics. I'll keep the original MSC and resistor in place for posterity, but they won't be connected to anything. With a rated torque of 42 oz-in (3 kg-cm), I'm surprised the original Airtronics 94102 servo was able to steer the truck at all. Keep in mind that a single servo drives all 4 monster wheels.

All right, let's tear this thing apart. There is a LOT of hardware in a Juggernaut. Seen on the left are all the nuts, bolts, screws, clips, washers, ball joints, and springs. Time (and an over enthusiastic use of thread lock) had taken its toll on some of the hardware. Shown at right are a sampling of the parts which broke or stripped during disassembly. Luckily, all are common parts and were easily replaced.

On the left are all the original links. There are 8 identical suspension links and 6 steering rods. I did not bother removing the rod ends from the links as all were in good condition. I only adjusted the lengths as necessary. On the right are all the non-fastener hardware bits, mostly all metal. Represented we have gears, bumpers, leaf springs, axles, motor plates, and lots more good stuff. This is the heaviest section of parts.

This may not look like all that many plastic parts (and it isn't), but many of them are very large including the axle housings and battery tray. There were no broken plastic bits to my great relief. On the right you can see the pile of original bushings. Only 4 ball bearings were used in the original kit, but I replaced everything shown with brand new rubber shielded ball bearings.

Working in batches, I loaded everything into the ultrasonic cleaner and tried to get all the old dirt and grease removed to make the parts look as new as possible. The results are shown above. On the left are all the fasteners and on the right are the rest of the metal parts, fully knolled.

One of the biggest problems with vintage RC bodies is the tendency of the stickers to lift and peel. That means that intentionally removing them should be easy, right? That's what I thought, but I was very wrong. The stickers proved to be incredibly stubborn and had to be individually chiselled free with a wedge tip blade. It took me hours. The result is shown on the right. You can see discoloration where the stickers were. Actually, what you are seeing is yellowing everywhere else but protected areas behind the stickers. No matter, I am going to paint this anyway.

For some reason I did not take any pictures of my tire restoration project, but it probably consumed the most time. Given that the tires are unique to this model and cannot be replaced, I wanted to make sure they were soft and supple, not hard and cracked. The best way to do this, as I've been lead to believe, is to soak them in glycerin. Sounds simple enough, but these are very big tires and they were not actually made to be removed from the wheels. The Juggernaut shipped with the tires and wheels already assembled for good reason; they don't stretch and are pretty much impossible to remove without destroying them. That meant I needed to soak them as an assembly, but the only way to get the glycerin to flow inside the tire was to vent them and then submerge them for many hours to allow the viscous fluid to bubble in. Then I had to try to squeeze it all back out of the now incredibly heavy tires, a process which took even longer. It took me the whole weekend, but I finally got a set of new looking tires. I wasn't able to patch the tear in the sidewall of the single damaged tire without access to the interior, but it seems to be stable and not growing. The cleaned tires are pretty slippery and will sometimes spin in the wheels. It's like a free slipper clutch.

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