2018 - Traxxas T-Maxx Classic #2 Electric Conversion
back to Fyrstormer's Garage
I finished another build today.
I can hear you now: "Wait a minute, fyrstormer. Why did you build a second T-Maxx? You already have one! See? It's right here."
"I don't understand, fyrstormer. I've read and memorized every word of every build thread you've ever written, and it isn't like you to build a second vehicle just to have one in a different color! After all this time, I thought I knew you so well, but now I don't know what to believe anymore! Are you feeling okay? Do you need help? I can call someone for you, just don't do anything foolis--"
"...wait a second. What's that thing where the exhaust outlet is supposed to be?"
"Oh hell, you've gone and done something weird again, haven't you? Well that's typical. And here I got all worked up for nothing. I hate when you do this to me, fyrstormer. I just can't handle your drama anymore. I'm leaving, and this time it's for good."
:D
So yeah, this T-Maxx is electric. Why not just buy an E-Maxx? Because I have a kink for electric 2-speeds with mechanical brakes, and the easiest way to get that is to do a nitro-to-electric conversion.
There's not a whole lot to say about this build that I haven't already said about my first T-Maxx build. Both trucks are built as close to identical as possible, using the same driveshafts, the same T-maxx 3.3 transmissions with reverse kits installed, the same aluminum chassis braces and RPM bulkheads, the same custom-made front swaybars, etc. The only difference besides the power source is this truck has T-Maxx 3.3 diffs filled with diff oil, whereas my first T-Maxx is still using its original non-sealed diffs filled with silicone grease. (they will get upgraded eventually; it's just such a pain to get to the diffs on the T-Maxx, and the old diffs still work fine even if they aren't as tuneable.)
I did have to go through some trouble to fit the electric motor and battery tray to this truck, though. I wanted to use a Titan 775 motor, because it's plenty of power for this truck and it makes more sense to run a 2-speed transmission with a brushed motor instead of a brushless motor. Unfortunately, there's only one motor-mount on the market that will fit a Titan 775 motor to a T-Maxx, sold by How2RC, and it's a simple die-cut sheet of aluminum. Not only that, but the motor is mounted unnecessarily high above the chassis plate, so a battery can fit underneath the motor. That's not the battery position I wanted, and it also lets the mount flex too much -- I could change the gear mesh by wiggling the mount with my bare hand. I sat on it for months while I pondered what to do. Eventually I decided to suck it up and re-cut the motor mount to position the motor lower.
As you can see above, I had to angle the slots to position the motor further to the side, so it would still mesh properly with the motor positioned lower, since the spur gear is round (obviously). It was a huge pain to make those cuts without mangling the motor mount, but it did work. It also fixed the problem with the aluminum flexing a bit too much, because there is now less distance between the motor and the anchor-point on the chassis.
Installing the battery tray was much, much easier. As with my HPI MT2 Electric conversion, I used the Axial SCX10 II battery tray because it lets the battery stand on its side so it takes up less space. But after getting myself absolutely filthy with oily aluminum dust while cutting the motor mount, I had no patience left and put the truck back on the shelf for a couple more months. This past weekend, though, I finally had a "come to Jesus" moment regarding this build, and in a desperate last-ditch attempt to avoid actually coming to Jesus, I gritted my teeth and drilled holes into the chassis to mount the battery tray.
That's about all there is to say about this build; like I said before, everything else is identical to my first T-Maxx build. (build thread here.) It drives quite nicely, and gives me a monster truck that I can easily drive in grass, unlike my smaller Stampede 4x4 which struggles when the lawn hasn't been mowed in a couple days. On a minor note, I'm rather pleased I was able to position both the motor and the power source in the same places the engine and fuel tank used to be.
It feels good to finally have this build done. 3 months until D-Day, so I'm running out of time to finish my RC projects.
Tiny update to this truck: It didn't go as fast as I wanted it to, but I already had the largest Mod 0.8 pinion offered by Robinson Racing (26t), so I started looking around for other options. It turns out Traxxas has a 34t Mod 0.8 pinion for their new 1/6-scale Desert Truck, so I bolted one of those on and the top speed went up from 30mph to 35mph. (for you math nerds, that's a 16.7% increase in speed, which is actually more than the 14.3% I predicted using the v(new pinion ÷ old pinion) formula, which means this motor is nowhere near being overloaded.)
Conveniently, the slots I cut in my customized motor mount are just wide enough to allow this pinion to fit without needing a smaller spur, which means I still have more up-gearing I can do if I decide to do that in the future. I'm sure the motor could handle it -- it is fundamentally a power-drill motor, after all, and its specialty is producing a crap-ton of torque -- but I don't know yet if I actually want the truck to go any faster than it does now. Better to work my way up than to shoot for the moon and smash the thing to pieces, after all.
back to Fyrstormer's Garage
Comments
Post a Comment