2017 - Traxxas TRX-4
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Traxxas was late to the scale-crawler game with the TRX-4, and even I already owned two other scale crawlers by the time the TRX-4 arrived. But when I saw what it was equipped with, I had to buy one anyway. A 2-speed transmission, portal axles, and remote-lockable diffs right out of the box?? Yes please! I don't even care if most of those features aren't actually useful for comp crawling, because I don't compete anyway, I just want those features because they're awesome. And I'm not the only one who thinks so, because I've read plenty of comments on many forums where owners say the TRX-4 is the best scale crawler they've ever driven -- once the "weight problem" is fixed.
Thus far in my ownership, the "weight problem" is the only problem I've actually encountered; the fully-accessorized Land Rover Defender body is tall and heavy, and the battery tray lifts the battery pretty high to clear the complex drivetrain (at least if you use a full-size battery -- there's a lower indentation to hold small batteries if you're cool with sacrificing runtime to get a lower CoG), so the truck is tippy in stock form. I wasn't willing to compromise on the detail accessories or the battery size, though, so most of my "work" for this build actually consisted of sitting around and waiting for manufacturers to make weighted parts for the drivetrain.
Anyway, here's what mine looks like:
I do love scale-accurate headlights on my scale crawlers. This truck has generic orange LEDs for the corner indicators, yellow LEDs from SuperBrightLEDs.com for the foglights (it's hard to find "yellow" LEDs that aren't actually some tint of orange instead), and Nichia DS Warm White LEDs for the headlights which look much more realistic than the cheap blue-white LEDs used in commercially-available lighting kits.
No, the asymmetric taillight setup isn't a wiring defect; that's how Euro-spec foglights work. Having one extra-bright light on the rear-left illuminates the corner of the car closest to you when you've just finished passing another slow car in the left lane, so you don't accidentally merge to the right and crash into it. Also, symmetry-breaking makes it look strange, so you notice it more easily when you can't see very well. So now you finally know what's going on when you see a VW, Audi, or Volvo driving down the road in perfectly-clear weather with the left taillight inexplicably brighter than the right taillight -- it's not because a lamp burned-out on the right side, it's because the driver of that car is driving with their foglights on for no good reason. Now you have one more reason to be angry at idiot drivers on the road. ;) Sharing is fun!
You may have noticed the diamond-textured kickplates and mesh window grilles in previous photos; here's a closer look. I don't normally go for stuff like this, but when I was browsing Google Images for inspiration, I saw these parts and decided to give them a try. For direct-from-China eBay parts, they're actually quite good; they are actually made of steel, rather than cheap metal-finished plastic, so I don't have to worry about the surface treatment wearing off to show crappy translucent plastic underneath. They do nothing useful, of course, but they do help dress-up the rather large expanses of plain black plastic and plain black window decals that came with the body. You can also see where I removed the entire rear rack from the body; I may put something on there eventually, but the huge heavy spare tire was just too much dead weight in exactly the wrong place. It looked great, to be sure, but there's a difference between useless decorations vs. counterproductive decorations, and sadly the rear-mounted spare tire was in the latter category.
Okay, so I haven't actually discussed anything functional about this truck yet, and there's a reason for that; I haven't needed to do anything to make it run better.
As you can see in the picture above, the layout of the truck is essentially identical to the factory configuration. I replaced the Titan 21T 550 motor with a Holmes Hobbies TorqueMaster Pro 27t 540 motor, because that's the same motor I use in all of my other scale crawlers, and I replaced the plastic motor mount with a STRC aluminum mount (feel free to give Traxxas crap for using a plastic motor mount -- that's just a dumb idea), and there are extra wires running around for the motor endbell fan and the headlights, but that's basically it. The only drivetrain modification I made was to install the optional smaller spur gear and the largest pinion that would fit, so I could get 13mph in high gear on a 2S battery. Everything else works the way I want in stock configuration; how often have I ever been able to say that before??
So if all I did to the drivetrain was replace the motor and change the gearing, why am I now posting a picture of the front axle? Because there are a couple non-drivetrain upgrades I installed that are worth mentioning:
The STRC diff covers are clearly visible; I like having aluminum diff covers to act as bash-guards to protect the rest of the diff pumpkin from damage. The steering and suspension links are titanium, made by SSD, which frankly I only got because the stock steel ones were starting to rust. Traxxas deserves points for actually equipping a scale crawler with steel links out-of-the-box, and as far as I know, the other major brands *still* don't do this. If Traxxas had used stainless steel, there would be no reason to replace the stock links at all. But the most important upgrade is the understated black STRC portal-axle hubs -- those suckers are solid brass, several hundred grams of the stuff, as low on the chassis as is possible. STRC got my money because they were the first company to make a matching set of inner and outer, front and rear, which other brands inexplicably refused to do. I couldn't find brass inners for the rear axle from any other brand. That's fine though, I like STRC parts. So anyway, those huge chunks of brass, combined with the Pro-Line FaultLine 1.9" beadlock wheels that I use on all of my scale crawlers, do an excellent job of fixing the "weight" problem caused by the heavy accessorized body shell.
A couple final details I want to mention:
On my other scale crawlers, I used Losi Mini-T rear shock springs with washers soldered to the ends to make spring-loaded contacts for the body-mounted lights, but that wouldn't work on the TRX-4 because of the body-post design. My other scale crawlers have separate body posts, at least in the front, so a spring can be installed around each post for separate positive and negative electrical contacts. For the TRX-4, I ended up buying some battery-compartment electrical contacts on eBay, bolting the spring contacts to the front body-mount tower, and sticking the springless contacts to the underside of the body shell with foam tape, to make a set of spring-loaded contacts for this truck. The springless contacts are domed, which helps the spring contacts to self-center on the springless contacts when they touch; obviously they were never designed to work this way, because they're intended for use with batteries, but conveniently it works for my purpose anyway.
The front foglights on this truck are from the Axial universal headlight kit, but the rest of the lights are molded into the body and needed a different solution. Traxxas' lighting kit has arrays of surface-mount LEDs attached to circuit boards for the headlights, but I don't like that look; instead I shopped around on eBay for parabolic-style light buckets that would fit the TRX-4, and I found some 3D-printed light buckets from a company called "GRC". This is the first time I've used 3D-printed parts for anything, and I'm pleased with how they turned out. I painted the reflectors with Spaz Stix Ultimate Mirror Chrome airbrush paint (using a normal paintbrush, but it works fine anyway), so they would be more reflective, but other than that the 3D-printed light buckets worked perfectly out-of-the-box, no modifications needed. They are well-made and fit just right, which is always a gamble when buying aftermarket parts.
So that's my TRX-4. This is the last RC project I will have time to finish before my screaming pooping bundle of joy arrives, and it's anyone's guess when I'll have the time and money to work on any new RC projects. I'm glad I got this one done while I still could, because it looks good and drives well.
Thanks!
Oh, I forgot to post a minor update; I took the advice of someone on RCCrawler and got an aftermarket accessory mount for the tailgate from Shapeways, so I can have decorative bits on there without the glaring hole left by the missing spare tire:
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