Arrma OEM Nero Diff Brain and OEM Upgrades Installation

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Northwest Pennsylvania
Arrma RC's
  1. Nero
  2. Senton 6s
Hey all,

I purchased a Nero without Diff Brain about 3 weeks ago. I bought the wrong chargers initially so I had to wait for a different one. Then I decided to purchase the Diff Brain upgrade kit with all of the Tower Hobbies E-Cash I earned from buying the Nero and batteries. I also found an Arrma OEM wheelie bar on Ebay and back-ordered the dirt guards from Tower. It rained like crazy for several weeks here and then my lawn tractor broke down so I never had time to take the Nero out. I decided I was going to put the Diff Brain kit in and put all of the upgrades on the Nero before I took it out for it's first run. It's much easier to work on a clean, new truck, isn't it? This morning I pulled everything out of the box, put the truck on the stand and did a brief bench test to make sure that the electronics and driveline were in working order. After that, I got out my wrenches and set to work. I have watched the excellent tutorial video on installing the Diff Brain probably 5 or 6 times and just watched it twice Tuesday night at work to make sure I had some idea what I was getting into. The truck came apart with very little hassle. The biggest suggestion I can make to anyone who is having trouble getting the motor and center differential housing out is to remove the side-by-side wire harness clip that's on the servo side TVP.. There's nothing attached to it and removing it allows you just enough extra wiggle room to get that big assembly out of there. I'm not really sure what it gets hung up on but it's a miserable pain in the butt trying to get it out until suddenly it drops free with no warning or apparent user interaction. The front and rear differentials came out like a dream and installing the Diff brain servos was relatively simple. I was careful to clean up some flashing on the actuation arm to avoid any binding. A couple of the arms had some pretty significant flash that had not been cut off at the factory. The center diff is a little more labor intensive because you have to remove the slipper and the bulkheads to split the diff case but the Nero is really designed to come apart and go together pretty quickly. Once I had all of the servos installed, I hooked up all the wires to the Diff Brain Module and wired everything as if the truck were assembled. I hooked up a pair of batteries and tested all of the functions both by checking the lights on the Diff Brain module and by manually spinning the differentials. The front and rear diffs are very easy to check by hand. The center one is harder. Because the motor was already engaged to the spur and I didn't want to tear that back down again, I had to use the throttle to test it for lock and unlock. My solution was to put a 2mm allen wrench in the output shaft hole. With the diff unlocked, it worked brilliantly. With the diff locked, I bent the shaft of my wrench to a 15 degree angle before the slipper kicked in and saved the gears. And that was with nary a blip of the throttle. Lesson learned. At least I know my slipper is set. I unplugged all of the wires and reassembled the truck. It went back together nicely with only a few hiccups that I'll attribute to the learning curve of working on a brand new rig. While I had it torn down, I installed the Arrma wheelie bar. It's a very nice accessory and I really like how it's integrated into the design of the rear bumper of the truck. Time will tell if it's durable but aesthetics and engineering are top notch. I also installed the Arrma dirt guard set while the wheels were off. There's not much to say about them. They are pretty utilitarian looking but the fronts have a nice cutout so you can access a vital screw without removing the guards. For ten bucks I'd say they are worth the protection they'll offer the driveline.

This whole project took me about 3.5 hours and that includes having to fight off my almost 4 year old son who never saw the Nero before and really wanted to help. My only complaint about the design of the differentials is the orange gaskets. Once the wires have been threaded through them, they are impossible to get into the proper position. I think I'll probably enlarge the wire openings a bit to make them fit properly the next time I pull the diffs to service them. The only "Oh Crap!" moment I had during this project was finding a shim on the work mat from the rear diff while I was pulling apart the front diff. Luckily, I hadn't gotten too far into the front diff so I was able to break it down slowly to see where the shim went in the rear diff. While it's tempting to tear everything down at once, it's always best to leave at least one of multiple assemblies together as a reference in case you wind up with a spare part or two that you don't know what to do with. The manual and exploded view did not show the shim I needed a home for, so if I had torn down both diffs and had both shims floating free, I would have been in trouble.

Overall this was a very enjoyable experience and I gained a lot of familiarity and insight into how this truck is built and how it works. Arrma did a GREAT job designing this machine and although it looks intimidating when it's assembled, once you start breaking it down, it's very user friendly and made to be wrenched on.

Finally, if you're on the fence about getting the Nero with or without the Diff Brain, here's why I did it the way I did. I'm a Tower Hobbies Super Saver Club Member. The Nero without Diff Brain was on sale for $650 last month and I had a coupon for $100 off $599 so I paid $550 for the truck. Because of the truck, batteries and other necessities, I had $96 in E-Cash and another coupon that basically got me the Diff Brain for free. So for my few hours labor and the fun of doing it myself I got the $800 Nero (of course I'd save $125-150 with a coupon) for $550.

Thanks for reading this ridiculous wall of text.
Great job with the explanation. If you add photos it could be a great how to.
Indeed - very informative - need to lay down after all that I'm kidding - I tried to follow the instructions and the center did not just fall out all ez at all. Then - when I panicked and put it back in - the sniper clutch was loose - brought it to my hobby store and they tightened the clutch for free and sent me on my way......

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I was really focused on completing the task with the time I had so I didn't stop to take pictures but the video below is excellent and was the guide I used to prepare for the installation:

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