Toyota 4Runner Project

This is probably the most customized rig I have ever built in the sense that I chose all kinds of disparate parts and combined them together.  The story that goes along with it is even more convoluted than the truck and spans at least a year.  I can't remember for certain what came first, but I think it was the body.  Through various random Internet searches and discussion groups I became aware of a company called MFab which was making extremely accurate 3D printed scale bodies.  I tried in vain to find a web site with more information, but it turned out you basically had to already know their product catalog and then contact them through FaceBook to order.  The 5th generation Toyota 4Runner is an amazing looking truck and seemed like a perfect option for my next truck.  I really didn't have much idea what to expect, but I had seen photos of completed models built by others which looked amazing.  These are made to order and the predicted delivery time was 6-8 weeks.  I sent my money off into the void and waited.  I think it took more like 4 months before I actually got my shipment which consisted of a box stuffed with ~100 printed parts with no instructions or diagrams of any kind.

While I was waiting for the body to arrive, I had time to think about what chassis I should use.  Some time in this interval a new (but old) company called Element popped up on the scene.  This is a trail truck branch of Associated Electrics, so this is a company who presumably knows what they are doing.  Their  RTR offering using this chassis, the Sendero, didn't appeal to me, but they soon released a builder's kit which included only a chassis in kit form.  This chassis has some interesting features I haven't tried before including BTA (behind the axle) steering, meaning that the steering tie rod is behind the front axle so it won't hang on obstacles, and an overdrive transmission.  In the full scale world, the word "overdrive" usually refers to a gear ratio of 1:1 or greater, but in RC it means something quite different.  It means that the front and rear axles are driven at different speeds.  As an engineer, the first thing I thought when I heard about this was that it was the worst idea I'd ever heard.  Overdriving the front axle means that all of the gears in the model will be under constant added strain trying to react the slipping generated by the differing rotational speeds.  Many semi-respectable people seemed to think it was the best thing since sliced bread for climbing performance though, so I figured I would give it a shot.

The Enduro chassis kit doesn't come with any wheels and tires, but I had a great plan there as well.  It just so happens that the stock plastic beadlock wheels from a Gmade Komodo look very much like Toyota TRD wheels.  I replaced the wheels on my Komodo with aluminum upgrades which meant I had a set of these wheels just lying around.  At the same time, I was selling off my LEGO Technic collection and some of my cars were using RC tires.  One of them, a Jeep Wrangler, had a set of 1.9" Proline BF Goodrich All Terrain T/A's which also just happened to be lying around.  These are the exact type of tires often seen on 4Runners, so everything was coming up Milhouse.

Then things got even better (except for my wallet).  After the body had arrived, but while I was still in the phase of too intimidated to start building, Element came out with an upgrade kit for their Enduro chassis which replaces the solid axle front suspension with independent front suspension.  For a Toyota, this would be perfect.  I ordered it and added it to the stack.

It took a long time before I felt motivated to brave to long dark of Moria and start building.  The chassis went together with no problem at all, and I converted to IFS immediately.  I used a Reedy 5-slot brushed motor to keep it in the Associated family and paired it with a Hobbywing 1080 ESC and a Savox steering servo.  The body was an exercise in patience, puzzle solving, and frustration.  The finish of 3D printed parts is pretty terrible, so even after figuring out how to assembly the massive number of parts I still needed to sand and fill about 6 times before the finish was remotely acceptable.  I worked on the body for hours a day for weeks.  The end result looks very good, but still lacks an interior which I'll obviously need to add, probably by scratch building.  Once they body was done, there still remained the problem of figuring out how to mount it.  Drilling holes and using body posts was out of the question, so I ended up making my own mounts out of steel angle brackets.  I also added a custom installed servo winch.  I came back much later and added a simple light kit.

So after all that, how did it turn out?  The model looks amazing despite some major errors during the painting process.  The CG is a little high which requires some care while driving and the mirrors break off any time it rolls over.  Other than that, the performance of the chassis is excellent.  The low speed performance in particular is amazing, and the suspension looks just perfect articulating over obstacles.  Strictly speaking the tires are probably too large and 1.55" or 1.7" wheels would be more scale, but it still looks really good.  What about the overdrive?  From what I can tell, it is irrelevant.  I built the model with about 6% front overdrive and I can't detect any difference compared to any of my other chassis.  I'm in mostly forested terrain though, so maybe things would be different on rocks.

Update:  This model was destroyed in the 2022 fire.  It has not been replaced.