2014 - Axial Wraith
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I finished my Wraith build. I did a whole bunch of stuff to this vehicle in a short amount of time:
- Replaced the motor
- Rebuilt the transmission with hardened-steel gears
- Replaced the 48-pitch pinion and spur gears with 32-pitch gears
- Replaced the stock driveshafts with MIP hardened-steel driveshafts
- Replaced the diff gears with Hot Racing hardened-steel gears (including an overdrive gear for the front axle, to improve "grab" when climbing and reduce "push" in corners)
- Replaced the front dogbones with RC4WD CVDs
- Replaced the stock plastic hubs with TopCAD aluminum hubs
- Replaced the stock plastic front bumper supports with RC4WD aluminum supports
- Replaced the stock wheels and tires with R35 Ripsaws mounted on Axial Walker Evans beadlocks (including Vanquish aluminum SLW spacers)
- Added 2oz. Axial clamp-on weights in the front wheels, to lower the center of gravity a bit
- Rebuilt the shocks with aluminum bodies, mounts, and spring collars
- Replaced the stock plastic suspension and steering linkages with titanium linkages from Blue Monkey RC
- Added bash guards from Blue Monkey RC
- Replaced the stock servo with a Hitec HS-7955TG titanium-gear servo (including an Axial clamping 24-spline servo horn)
This is a high-torque vehicle and I don't like breaking parts, so from the motor spindle to the wheel hubs, the only parts of the drivetrain that *aren't* made of hardened steel are the spur gear and the diff bodies -- everything else is rock-solid.
The suspension and steering linkages are titanium, because I know perfectly well they're going to get bashed into stuff and dragged over rocks, and neither plastic nor aluminum will hold up as well as I want. The lower suspension links are a high-clearance design, which helps a bit, but there are obvious scrape-marks on them already, so I'm confident I made the right choice in getting the more expensive titanium links.
Various people told me I didn't need bash guards for the diffs, but after seeing how quickly the diff covers were getting chewed up, I decided to get bash guards anyway. Blue Monkey RC makes a nice set that have a low profile and are made of steel instead of aluminum, so they can actually do the job that bash guards are supposed to do.
This is what they looked like new:
...and this is what they look like after a week of unapologetic bashing:
The rear bash guard doesn't look as bad, but it's got its fair share of scrapes on the underside. The important thing is, the replacement diff covers I got still look pristine, instead of having the fins bent and broken off, like the original pair had.
I don't like plastic shocks, but I didn't like the look of the Axial aluminum shocks, so I bought green and black aluminum parts from STRC, and rebuilt the stock shocks. They work a little smoother, just like metal shocks always do.
I opted to keep the speed of the stock motor, but I wanted more durability, and I didn't want to drop a bunch of money on a sensored brushless system, so I opted to install a name-brand rebuildable brushed motor. While it was originally intended for something more like a touring car or a go-fast monster truck, this Team Orion 20-turn motor is holding up great in my Wraith. It doesn't get too hot, the battery lasts forever, and it produces noticeably more torque than the original throwaway motor did. I added silver brushes to improve conductivity, and the next thing I noticed was I had to tighten the slipper clutch to keep the motor from spinning freely when I pegged the throttle, so that improved torque output as well.
In the three weeks I've had it, this vehicle has completely supplanted my go-fast vehicles as the vehicle I'm most likely to play with on any given day. It comes with lights, so I can run it in the dark after I get home from work, and the fact that it climbs over stuff instead of going fast means that I can actually have fun with it in the dark without worrying about destroying it against the side of a curb. This vehicle is one of my best RC purchases to-date.
I could make my own video, but I won't be able to do better than the video that convinced me to buy a Wraith:
I've made a few changes to this vehicle since I "finished" building it. I removed wheel-weights from the front wheels and replaced them with a big block of lead stuck on top of the servo. I also replaced the TopCAD aluminum steering knuckles with STRC steering knuckles, because the TopCAD knuckles weren't strong enough.
This is what a quarter pound of lead ballast looks like:
And here are the new steering knuckles:
I also installed the Dig kit for the gearbox; it's interesting, but I'm still deciding whether I want to keep it long-term. It's not doing any harm being installed though, so for the time being I'll leave it in there.
More changes. I burned-out a second Team Orion 2x20T motor, so I switched to a Tekin 35T motor with much higher gearing, so I could get comparable top-speed while still limiting the maximum current that could flow through the motor when it stalls. I was unimpressed with the performance, so I replaced the motor again, this time with a Tekin 30T Pro Hand-Wound motor, and I found some old Trinity silver laydown brushes on eBay to use with the motor. I was pleased to see the Tekin Pro Hand-Wound motors also have lathed commutators; that made break-in a hell of a lot easier.
At the same time, I also concluded that I simply had no use for the Dig function that I'd added to the stock gearbox, and I really wanted to avoid burning out yet another motor, so I also replaced the stock gearbox with the RC4WD AX2 gearbox. Once I settled on suitable gearing (17/54), I was able to get the same as the original top-speed in high gear (about 12mph) while getting a decent 4mph in low gear -- as well as 3x more torque in low gear, which means now when grass and small vines get wrapped around the axles, the truck just tears them out by the roots instead of getting stuck.
I had to cut away some of the plastic on the top side of the center skidplate so the AX2 transmission could fit with the optional gear cover installed, but it was worth it. This transmission is rock-solid, and it gives me the flexibility I've been looking for without having to wedge a sensored-brushless ESC into the chassis. (there's not a lot of room in there, I'm sure you've noticed, and I hate sticking electronics inside the "passenger compartment" where they would be visible.)
Here, have a running video:
The Tekin 30T Pro Hand-Wound motor I'm now using works great, but I still saw operating temperatures higher than I'm comfortable with, so I added an endbell fan to the Tekin motor, using MuchMore Racing endbell fan screws that are nearly impossible to find anymore. The fan is a Sunon chipset fan with dual ball-bearings, and the deeper profile (15mm instead of 10mm) means the fan blades can be a little more efficient than they would be if they had to be shorter.
This involved adding a power tap to the ESC, because I wanted to run the fan on full battery voltage, instead of the weak 5V coming out of the BEC.
I tested various spots on the circuit board until I found one that provided full battery voltage, but was still switched by the main power switch, so the fan shuts off when the ESC shuts off.
The cutout that I made in the center skidplate a few weeks ago, to accommodate the fan, was almost perfect; it just required about 1mm of trimming to make sure the fan didn't actually touch the skidplate.
The cutout that I made to accommodate the AX2 transmission's spur gear cover is also nearly perfect, which I never noticed before. It's especially impressive because I totally just eyeballed it, I didn't measure anything.
There is officially no room left in the transmission tunnel on my Wraith. It's a wonder I can even manage to run wires through it anymore.
I ran it last night and never saw a temperature higher than 90F, which is about 75F lower than I'd seen before with this motor. (admittedly it was 32F last night, so the motor will get a bit warmer in the summer.) Hopefully I'll never burn out another motor in this truck.
A few more mods I just finished up:
Front fenders, to keep debris out of the "passenger compartment". I might install rear fenders too, eventually, but the fronts were such a pain to trim, test-fit, re-trim, repeat, that I won't be doing the rears any time soon.
I added extra screws to keep the fenders secure; 2 along the side and one at the top, on the underside of the spot where the front hood screw goes in. I had to shorten the screws sharing that screw-hole by about 1mm to make sure they wouldn't collide with each other. The rest of the screws I just drilled into convenient bits of rollcage where I knew other screws weren't passing through.
I also added extra screws to the roof, to keep the corners in-place. I put one at the front corner, and two at the rear corners. Now they won't get lifted-up and get debris jammed under them.
Due to recent changes in the suspension (lengthening the lower suspension links to tilt the axles to a more horizontal position), I realized I could now add more ballast to the front axle without having clearance problems. So I added another layer to the big lead block I had previously stuck on top of the servo, to bring it up to a total of 6 ounces (or 132 grams, if you prefer).
I thought I would be done with this build a long time ago, but the strange thing is, the Wraith keeps benefiting from incremental improvements almost endlessly, whereas my other vehicles hit a pretty clear point of diminishing returns where spending more time and money didn't accomplish much. It's an odd vehicle in that regard.
I just spent most of the afternoon and all of the evening wrangling a new ESC into my Wrath. The old ESC seemed to be getting weaker with age, and now's as good a time as any to replace it.
Anyway, the ESC I installed is an Axial AE-5, to replace the AE-2 that came with the truck. It's a simpler ESC, but to be honest I wasn't using any of the fancy features that the AE-2 supported anyway, and when I plugged in my Castle Link to check the settings on the AE-2, I realized I was using 50% drag-brake -- spot-on one of the settings offered by the AE-5. That combined with the fully waterproofed circuit board and power switch, and the fact that I'm already using the AE-5 in two other trucks so I'm simplifying my spare-ESC collection by ditching the AE-2, made the AE-5 an easy choice. All I had to do was figure out how to make the freaking thing fit.
The Wraith came with a pile of unused kit-parts, one of which was a flat ESC mounting plate that could be used in-place of the facehugger-style plate that wraps around the stock AE-2 ESC. I tried it in the original vertical orientation, but it didn't allow enough room for the AE-5's tall heatsink. I noticed there was a hole near the top of the flat plate, so I flipped the plate around and realized I could also mount it in a horizontal orientation and stick the AE-5 on top of it with servo tape. The only modifications I had to make were cutting off a small alignment pin from the bottom of the plate, and countersinking the hole near the top of the plate, so there would be a flat surface to stick the ESC to.
Unfortunately this meant the ESC would interfere with the shroud that covers the wires coming out of the receiver box. In a fit of exasperation, I cut the overhang off the edge of the shroud, so the edge of the shroud would be flush with the rear wall of the receiver box, and then I stuck a piece of dense foam tape to the inside of the shroud so it would seal tight against the wires. I think the receiver box may actually be more water-tight now than it was before, when the shroud was open and relied on air inside the box to keep water from intruding.
Also, I despise having to dig into that box, so I put a couple short servo-cable extenders in there for the steering and shifting servos to connect to, so I could disconnect them when I remove the front axle and/or transmission without having to open the receiver box. As a bonus, the servo-cable extenders are flat, whereas the servo cables are twisted, so the foam tape seals better around the extenders than it would've around the servo cables.
The last annoying tedious task was bundling the excess wire length that had previously been stuffed inside the receiver box, and routing the motor/fan/shift-servo wires through the transmission tunnel. Mercifully there were no major problems with getting wires to fit around the transmission and actually reach what they needed to connect to.
I love vehicles with frame chassis instead of flat-pan chassis and Lexan covers, but good lord they're hard to work on sometimes.
I installed a little upgrade today:
After two years of faithful service, I decided maybe it was time to upgrade the diff clamps. Nobody will ever see the pretty green color, but they all cost the same amount, so I went with the color that matches the other STRC aluminum bits on the truck.
For a while I've felt like the Tekin Pro 30T motor in my Wraith was underpowered, but 30T was about as high-powered as I could go without risking burning out the motor on hard climbs. (learned that the hard way.) Since I'm putting together a Vaterra Ascender and I need a motor for it, I decided to bite the bullet and get a Holmes Hobbies Torquemaster Pro 21t 550 motor for my Wraith, and put the Tekin motor in the smaller and lighter Ascender.
I'd already cut plastic off the center skid to accommodate an endbell fan for the Tekin motor, and conveniently the TorqueMaster Pro 21t 550 turned out to be the same length when fitted with a lower-profile fan. I'm not completely certain, but it looks like if I didn't have the fan I might've been able to fit the 550 motor without any cutting at all; it's only the support for the upper link mount that conflicts with the longer motor anyway, and since the endbell isn't completely round like it would be on a 550 brushless motor, the two parts might've been able to slot together without any cutting.
It does a very nice job of waking up my somewhat sluggish Wraith. The extra torque is very noticeable.
First change to this build in a long time: I replaced both the center driveshafts and the front axles with universals, because those hold-up better without frequent lubrication. They also look more scale-accurate.
I also removed the front spool and replaced it with a diff that I locked using JB Weld putty, so I could clock the outputs 90° out-of-phase. That way when the front-left universal is entering the "slow" phase of its rotation, the front-right universal is entering the "fast" phase, and vice-versa. This significantly reduces drivetrain vibration when cornering, which matters on the Wraith because it has a top speed of about 14mph in high gear.
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