Losi Mega Baja Brushless Conversion - Project Mega Green
By Tony Arnold - StampedeProject.com
It's funny how things snowball, one Novak 4.5R system in a Stampede years ago and now I am converting roughly my tenth large scale nitro truck to brushless. All the nitro guys ask me the same thing...Why, don't you enjoy tuning and the sound? They always seem to forget power, and no, my neighbors don't enjoy the screeching nitro sound. Lastly, as an old farm kid whose job it was fixing and tuning engines, I am sick of messing with engines. At this point in my life I would rather be driving than tinkering with the tuning on some picky nitro engine. Right now I am happy with the mind - blowing performance and power of brushless, the silent quiet that doesn't piss off my neighbors, and plug in an go convenience.
My latest project is Project Mega Green - a Brushless Losi Mega Baja/Aftershock/LST2. No I am not some tree hugger, but I do get tired of laying out $30 for a gallon of gas every month just for my nitro bashing RCs. In the spirit of attempting to be a little more green/cheap/lazy, having a brushless electric basher than requires no more than a charged battery seemed appealing.
Ok so it was technically a Mega Baja I converted, but we all know the Aftershock and LST2 are basically the same thing with different tires and bodies. The Mega Baja does have those huge Losi tires that allow it to go over just about anything and that bug body that my wife says is cute. Yep this is a perfect example of me tearing up something in perfect condition just to do a brushless conversion. Some other lucky ebay auction winner will I am sure be thrilled with the hardly used motor pulled from this RC.
Although it looks simple now, oddly enough this was one of my most difficult conversions ever. Going into this conversion, I really didn't think it would have been that difficult, however as I started digging in, I realized this would take a little head scratching. I started with disassembling the main chassis components to remove the braking servo and brakes as the motor is more than capable of handling braking duties.
It took an entire Sunday of tinkering just to come up with the slipper & spur gear mount. All the goofy one way bearings and superfluous three gear setup was removed for a simple single gear. The end result was a simpler solution of just using a Derlin spacer and bolting the second gear to it's clutch to effectively fake a standard slipper gear setup. How did I pick second gear to use? Easy it was the only one that I had a clutch on in that I could screw to itself. In retrospect I got lucky, 1st gear would have been way to low and 3rd would have made this thing a 60MPH speedster that stressed the electrics and ran hot. If Losi ever does introduce a brushless conversion kit they will also have to include a new spur upper transmission shaft for, because the simplest final solution was far from elegantly simple. It works, so no complaints.
The motor mount was also a little tricky as there is very little to mount to. I ended up fabricating a standard 1/4"motor mount plate and securing it with three machine screws from underneath the chassis deck and then notching out the lower chassis brace to allow room for the screw heads. I had expected the need for a secondary brace, however it seems plenty rigid at this point and has made it through a couple hours of testing without a problem - time will tell.
The huge Hacker C50L seemed up to delivering HUGE power. I fabricated a battery tray holder out of 1/8"diamond plate that can accommodate oversized high Mh 5S packs. The pictured 10,000 Max Amps 3S pack seems to be swimming in room, however my huge 5S Polyquest/Enerland packs need the extra room. I intend to run 4S - 6S eventually with one of the new Tekin Rx8 1/8th scale brushless ESCs. The battery tray is definitely a little big to accommodate the expected oversized packs, but I suspect there will be only a few times where standard sized packs will be long for the ride.
Initially I tested the setup without the fan cooled Mamba Max on 3S and it seemed to get a little warm, but didn't have any thermaling issues. On 4S I kept thermaling so the final decision was to add an industrial 12V fan, a Castle BEC. On three 3S the project Mega Green is a blast producing mid - 30MPH numbers easily and wheelies from a dead stop, on 4S 40+MPH is no problem and is a wheelie - ing machine.
Go faster, I don't thing so. It would be pointless since the LST frame really isn't designed for high speed - I would use my Revo for that, but the Mega Baja can jump like nothing else I have driven so it'll stay and under 40MPH jumper and bashing fun machine. As is It's geared and powered just about perfect for general bashing, jumping, and the occasional track assault, so I may even leave it as a 4S powered wheelie - ing, bashing, and jumping truck.
I jammed in old Traxxas receiver into the electrics box and left the servos as is and the conversion was done. Admittedly this is not the quality of some of the previous conversions I have done, however this one was one for me instead of destined for RC Car magazine. Also to justify my more sloppy work on this conversion, I have to note it took me over a month of 15 minutes here and there to do, because of the interruptions of life, vacations, and other articles. My quality of work tends to suffer if I can't have at least 2 hours at a time to work on the details of the conversion.
How does the Project Mega Green perform? The LST is neither my fastest or slowest of my RCs, but has the fun appeal of a really big 4X4 Stampede - Quiet, still plenty fast, and takes a beating like a champ. With the motor mounted in from of the transmission and the batteries at the rear, the Project Mega Green maintains the stock rearward weight bias. From a driving perspective, there is something I have always liked about the Mega Bajas. They are a blast to bash with, and those freaking HUGE tires role over anything. I actually ran the Mega Baja through a number of my 2.2 crawler lines and it just kept going despite not having locked difs. As an electric basher, it takes just abusive levels of behavior. Even though brushless is quiet, the metal on plastic gears produce a much quieter sound than typical metal on metal gear meshes of brushless buggy and truggy conversions produce. The sound is almost down right sneaky. So even in the quiet of the late evenings I can still be buzzing around without bugging my neighbors outside enjoying their deck and outdoor grills.