Tamiya Unimog Project

Page 2: Upgrades!

Wow, that's a big pile of upgrades. Prior to even building this model, I had scoured the globe for every upgrade part I could find with the goal of making my CR-01 entirely metal. I was inspired by a build on the Tamiya Club forum by Speedy. His build was in 2014, and since that time a large number of the upgrade parts have gone out of production so sourcing them was very difficult. In the left image above you see aluminum parts, a power system, magnificent servos, beadlock wheels, a high power BEC, and everything else I could think of. The one holy grail I was never able to find is the aluminum axle housings. The right hand image shows the contents of the RC Screws stainless screw kit. Installing these meant I had to pretty much tear the entire model down to kit form and start over. It was fun.

One of my main challenges was finding parts still available. GPM has long since stopped making CR-01 parts, but their parts were high on the list of things I needed. I was able to find an assortment of their out of production parts but only with blue anodize which is not what I wanted. Stripping the dye begins with soaking the parts in "Greased Lightning" cleaner for a few minutes, rinsing, and repeating. I went through about a gallon of cleaner for all these parts.

Here you can see my mixed results. The left hand image shows the parts after the first rinse. A few of the parts have almost total dye removal, but other parts like the steering hubs look almost like they did when I started. The right hand image shows the parts after the third rinse. Some are close enough to call done, but those hubs are still stubbornly holding onto their dye. I let the parts soak while I went to lunch which was a bad idea. The cleaner started attacking the base metal causing corrosion and pits.

Even after the dye is removed we're not quite done. The cleaning process resulted in a flat, dull surface which is not good enough for the kind of bling I'm looking for. I spent the day with a Dremel polishing wheel and some automotive wheel polishing compound shining up all the parts. It took pretty much the entire day, but I'm happy with the results.

My upgrade strategy was to disassemble the model into modules by following the instructions in reverse order, upgrading as I went along. The first thing I tackled was the axles. Front and rear axles are the same on this model, so I upgraded on and compared it with a stock axle. Aluminum upgrades include c-hubs, steering arms, shock mounts, spring supports, wheel hexes, and servo tray. I replaced the Savox 208 oz-in servo with a Protek 650 oz-in aluminum servo, the highest torque unit currently available as far as I know. I admit that appearance was at least as big a factor as torque in choosing this (very expensive) servo. I also added a Yokomo aluminum servo horn to handle all that torque.

The left hand image shows the stock frame with a plastic side plate, plastic shocks, plastic crank arms, and aluminum suspension links. The right hand image has added aluminum side plats and crank arms. I've also replaced the lower suspension links with bent arms which increase ground clearance.

Next comes the shocks. The stock shocks are not bad, they are oil filled plastic dampers. I replaced them with Tamiya aluminum dampers made specifically for the CR-01. These are really high quality aluminum body shocks with Delrin pistons and titanium nitride coated shafts.

Time to dig into the gearbox. Probably the most useless (and hidden) aluminum upgrade was the aluminm planet carriers, but it sure did look nice for the few minutes I could see it. The left hand image shows those planet carriers as well as the new motor mount and CR Tuned motor. This motor was a huge improvement in smoothness and quiet. In the right hand image I've added the aluminum center link mount and skid plate along with aluminum gearbox mounts.

Time to start making it look like a truck chassis again. The left hand image shows the axles attached to the frame with the new bent lower links, shocks, and barrel springs. The shock links (vertical links going from the axle up to the shock crank) are titanium. The front bumper has also been added. In the right hand image the center gearbox has been installed. You can also see the aluminum battery cover.

Rather than the very expensive and hard to find Tamiya upgrade drive shafts, I went for some steel telescoping CVDs from JunFac. I am pretty happy with the quality and appearance. The right hand image shows a bottom view of the chassis with all the shafts and links installed. Gorgeous! I like the mix of black and silver.

The stock wheels are actually pretty nice looking plastic beadlocks, but the aluminum beadlocks I replaced them with are even better and help to lower the center of gravity.

This pair of images compares the before and after upgrade chassis. From 20 feet away, you may hardly notice the difference. However a closer look reveals that virtually everything is now metal. We've added quite a bit of weight, but that's just fine for a crawler. Many of the metal upgrades do little to nothing for performance, but the shocks, barrel springs, servos, and tuned motor really made this a top performer. I love how it drives now.

The left image shows how many new stainless screws were left over. Some of these were just extras, but many others are due to the fact that the upgrade aluminum parts use different fasteners. The right hand image shows all the parts which were removed and replaced from the stock CR-01. This box would build almost a complete second kit.

The final step is to install the electronics. I used a Hobbywing Quicrun brushed controller which is super smooth along with a Castle 15A BEC to handle the current demands of those huge servos. It all works great. I was very careful to be neat with the wiring so that it does not detract from the appearance. The right hand image shows the TLU-01 light control unit and the LED wiring. Lights always do a lot to improve the scale look of a model, although this chassis is certainly nothing like a scale Unimog.

Once the body is on you would hardly know how much work into this model, but I know and it puts a smile on my face every time I drive it. Everything I installed is waterproof (except the light controller) so this is a model I am comfortable using in any terrain or weather.

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