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Arrma RC General Upgrade help Thread!

Arrma RC General Upgrade help Thread!

Old 03-26-2020, 02:17 AM
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Default Arrma RC General Upgrade help Thread!

Arrma RC Recommended Upgrades

Arrma Kraton 6S action shot from the company.

As you guys are surely aware, Arrma has gone from a small company about a decade ago to now being a real contender with the big boy companies such as Traxxas, Losi, and Team Associated. To celebrate, I figured I would offer up my upgrade list, separated into stages to make things helpful and useful for all Arrma lovers.

This list will be based off of the 1/8 Arrma Kraton 6S (prices are for K6S as well), as it is the most popular and most purchased truck from Arrma. However, because most 6S Arrmas share alot of their parts, most 4S models share alot of their parts, and so on and so forth, these same parts from the same companies are most likely available for your specific model!

How the stages will work, is they will be linear and progressive. This means that you must complete the upgrades for the previous stages to reach a certain stage. For example, to build a Stage 3 "Beastly Baller" truck, you will need to complete stages 1 and 2 as well (exceptions will be noted). Also, where aluminum upgrades are suggested, purchase 7075 grade aluminum or better. Alot of companies use 6061 grade aluminum, which completely ruins the entire point of the upgrade, considering 6061 is Arrmas stock aluminum grade. With that settled, lets get started!

Stage 1 "Bare Essentials Build": This build takes your stock, straight out-of-the-box truck and simply makes it last quite a lot longer (without breaking) using the least amount of money. Drive well, and don't do crazy 20-foot high jumps, and this will make your Arrma last for years to come, maybe even forever. Just as long as you do your standard full tear down and maintenance once every year and also as necessary (if things begin to lock-up or malfunction)
  • M2C/Voltage Hoobbies/JBIRC 7075 Chassis Braces - Front and Rear lowers (7075 Grade Aluminum ONLY) - $50
  • Shim your diffs and input gears/input pinions. There are a lot of different kits available that work. Ask around for recommendations. The most important things are the input gears that rotate the diff itself front and rear, as well as the larger "planetary" gears at the bottom and top inside each diff. The smaller spider gears inside the diffs are fine in most cases. Reassemble your diffs empty with half screws and test for smooth rotation before filling your diff up with fluid. Also check again after filling and final assembly. Adjust as necessary, not all trucks are the same, there are tolerances in manufacturing, this is a GENERAL guide - $5-$15 for shims plus $40 for diff fluids to refill diffs. I recommend 20K(F) - 200K(C) - 30K(R) setup for Kraton 6S that handles similar to stock but has more AWD power and a tendency to over-steer and drift on dirt, its a pleasure to drive! - $50
  • Aluminum Wing Buttons (Any Grade aluminum it doesn't matter). The stock plastic ones will break and your wing will not stay on for long if you land on the rear too hard - $10
  • 4 x M3x30mm Class 12.9 Screws - Socket Head Cap - 2mm Hex Tool Head. These screws are a bit more durable than the Class 10.9 screws that come on the Kraton 6S stock. These four screws are important because the stock screws in the top of the shock towers, holding the shocks on, can snap and break off as there is a lot of force and leverage on them when you land jumps. You can order online but might find them in your local hardware store - $3
  • Remove all 6 stock A-Arms, coat with a can of standard WD-40, and allow to dry overnight. The next day, wipe off any excess oil and reinstall. This will soften the plastic and make the arms function more like RPM aftermarket arms without the cost - $7 (Can of WD-40)
  • Add a bit of pre-load to all 4 shocks if you plan on jumping the truck more than two or three feet in height off the ground. I recommend setting to about halfway down the threads on the front, and just under half on the rear - $FREE
  • Check your screws. Go over as many screws as you can, checking for tightness. Screws going into metal should have a bit more resistance if thread-lock was properly applied. I like to back them off barely 1/4 of a turn, just to see if there is thread-lock, then just tighten them back up. No need to pull the bolts all the way out if they are resisting as they should. - $FREE (unless you don't have threadlock)
  • Check and set your stock A-Arm droop screws, I recommend screwing them just a bit further through for a little extra protection against damaging the shocks from over-extending them - $FREE
  • Recommendation: This setup is designed to be quite tough on 4S LiPo, but it isn't quite enough for 6S LiPo. The monstrous power of 6S will more than likely break a stage 1 truck after some time. But that is your choice. A 16T pinion is recommended for 4S and a 14T pinion is recommended for 6S (on the Kraton 6S with stock CopperHead tires). I only recommend Robinson Racing Pinion Gears (select Mod 1 with 5mm shaft diameter hole). These pinions are extra hard, high-carbon steel that Ive never even heard of someone stripping or breaking. They will cost you $12.50 each and one will be added to the final stage one cost. ALWAYS BE SURE TO ADJUST YOUR PINION SIZE IF YOU ARE RUNNING LARGER OR SMALLER AFTERMARKET TIRES!
Stage 1 Total Cost: $132.50

Stage 2: "True 6S Basher" build: So you haven't itched that itch yet huh? You want more power, more speed, and more air? Well having completed stage 1, you already have a lot of what is needed to make your truck ready for some pretty big jumps, around 10 feet high in fact. Lets go over stage 2 upgrades:
  • Metal Case Servo - The stock servo has enough speed and torque to turn the stock wheels and tires eh, decently we will say. However, it has a plastic case and there lies its biggest issue. After a few bigger jumps and hard landings, I broke mine, and most people report the same. Now a lot of people like to go fairly cheap and choose something like a low-end metal case Savox, or maybe something from a cheap off-brand such as a JX servo. Now those servos are okay, but in the end I wanted better steering and something that will last for years to come. Therefore - I recommend the Reefs RC 444 or 555 servos. Waterproof, all aluminum case, and massive torque (plus high speed for the 444) in a high quality package that competes directly with MKS, ProTek, and high-end Savox Black Editions, among others. Includes warranty, but it is fairly expensive. The 444 is recommended in all cases except the Kratons and monster trucks that upgrade to super-wide wheels and tires like ProLine MX38s, that will want the extra torque from the slower, but more powerful 555. We will talk about bigger wheels after all stage upgrades because they are not entirely necessary even through to the end - $110
  • New Radio System - Currently, most of the Arrma line is coming with a horrible radio system called the STX2, you will see this stamped on the controller. If you want to go fast, you will need to get rid of it for safety reasons. There are plenty of horror stories out there with runaway trucks due to the junk stock system. The FlySky GT3-B is the cheapest radio I have owned that is fairly decent, but you can take this as high as you want . - $40
  • Hot Racing/M2C/JBIRC/Voltage Hobbies Aluminum Servo Mount. The stock plastic mount will flex and allow slop in the steering as well as eventually break under the torque of an upgraded servo or a hard landing. I use the hot racing one just because its cheap and available plus when I got it, Voltage and JBIRC were unavailable. Its a small piece and doesn't need to be 7075 anyways, good old 6061 will do just fine here (Hot Racing Parts Grade) - $25
  • Aluminum Servo Horn and lead link combo from Hot Racing. The stock Servo horn will almost guaranteed strip out from the upgraded servo torque or some hit eventually. Plenty of companies make aluminum steering horns, and it can be 6061 or 7075, but hot racing makes this neat little combo that replaces the original lead link off the horn with an aluminum one when you buy the horn! Great value and really cleans up some steering slop. - $20
  • M2C/Voltage Hobbies (7075 Grade ONLY) Lower suspension mounts/suspension arm pin holders. The plastic stock ones do break on higher jumps, particularly with nose or rear tilted landings. If anything hits a wheel hard enough to push it backwards and bend the Arms back, you will probably break these. Theres a really nice set just invented by M2C that actually has threaded/captured Arm pins and Im going to be trying them soon, but they are expensive, and the Voltage option did cost me a lot less, its either $75 for 3 Voltage ones (one stock is already aluminum) or $150 for the M2C setup. I will be adding my current $75 setup to the total. - $75
  • Center Diff Aluminum Cup. Once you go 6S, the diff fluid will actually begin overheating the stock center diff cup (depending on fluid choice). When the truck does a wheelie, the faster spinning of the front wheels causes that diff to work very hard, so if you want to continue driving it as a Truggy with real diff action to keep the wheels down for high speed, then you will need an aluminum cup because eventually, the heat does warp the cup microscopically and that is enough for the spider gears to become mis-aligned. This is why people report destroying diffs all the time on 6S. Luckily, with thicker fluid in the front and rear diffs, they don't do quite as much work and they should be ok on stock plastic, but you can always buy more cups, and it is recommended for the final stage to have all aluminum cups. For now, I will add the cost of a single Integy Racing Billet Cup. - $30
  • T-Bone Racing or RPM Front Bumper. The bumpers do snap off on larger jumps that land on them, or in high speed crashes. You want them plastic, no need to send that shock to more vital components, but these upgrades are softer plastic that takes a lot of bending to break, it will work for quite some time. The rear bumper will be addressed in the next stage, as the front is much more likely to get broken. I mean, how often do you do 40+ MPH in reverse, or hit a big jump in reverse? RPM is cheaper, so it wins for now (there is a really good Arrma "Safety" kit available from POS racing in Germany that includes both bumpers and skid plates if you want the ultimate setup for stage 3 or higher builds, but much more expensive) - $20
  • Recommendation: This setup is designed for pretty big air and big speed, but it is not super strong for those absolutely massive 20+ feet high jumps. If you try those on stage 2, you will likely bend your chassis and snap A-Arms. Those will be discussed in stage 3
Stage 2 Total Cost : $455 ($135 Stage 1 + $320 Stage 2)

Stage 3: "X-Maxx Killer", "Thor's Hammer", or "Beastly Baller Basher" - These names all accurately describe a Stage 3 Kraton. If you think your wallet is in a lot of pain after stage 2, things are about to get much worse. However, this is where the big boys play... A stage 3 Kraton will jump off a 2-story building and survive, it will go head on into a concrete wall at 50 MPH, and survive with little or no damage. You can "SEND" a stage 3 Kraton "To the Moon and back", and it will survive. Kevin Talibot on YouTube, someone who treats RCs worse than even Rich Duperbash does, finds it nearly impossible to break a stage 3 Kraton. Its just too tough, even jumping 30 feet high out of a bowl at a skate park, and smashing the truck onto concrete. This isn't completely guaranteed, nothing in the RC hobby ever is, but this is where it seems to be possible to do almost anything to an Arrma, and it will drive away. So without further delay, lets get started:
  • M2C Racing 7075 Aluminum Chassis. The stock chassis will eventually begin bending under the stress of landing big jumps, even with the upgraded braces. All the braces do is make the stock chassis and shock towers last a bit longer on slightly bigger jumps. A bent chassis puts strain on the drive-train and other connected components, leading to more breakages. Once its more than slightly bent (like 10 deg), its time to chuck the stock chassis in the garbage. Upgraded chassis can be had from a few different manufacturers, but the M2C one is the best. JBIRC has one as well but its made from 6061 and therefore had to be thicker and heavier, which leads to more force coming down from a jump, and therefore more breakages. They are about the same strength and same cost, so why not get the better one? - $130
  • M2C/Voltage Hobbies (7075 Grade ONLY) Shock Towers, front and rear. Its time to also address those bending shock towers before they also get too far and start breaking other components. - $80
  • Aluminum Steering setup - the plastic parts inside the steering bellcrank assembly are likely to start breaking so lets upgrade with the entirely aluminum set from Hot Racing along with a Voltage Hobbies/M2C 7075 steering rack/akerman bar (NOTE: Tighten the servo saver down at least somewhat, it comes very loose out of the box) - $55
  • RPM A-Arms all around, all 6 arms. Stock Arrma plastics are just a bit too hard and brittle of a compound to survive the really hard landings. The WD-40 softening helped, but this is just too much, and the sets aren't that expensive anyways - $25
  • Pair your new arms with better M2C Arm/Hinge pins as well as their droop screw kit (unless you opted for the captured/threaded system) - $38
  • POS Kraton Complete Safety set - will protect your Kraton with the best designed bumpers and skid plates available on the market - $55
  • Shock Fluids - The Kraton actually comes with pretty thick shock fluid for dampening right out of the box (Front 800, Rear 550 CST) but it might not be quite enough for the type of bashing we are doing at this point, recommend 900 CST front and 700 Rear - $15
Stage 3 Total Cost: $855 ($135 Stage 1 + $320 Stage 2 + $400 Stage 3) [This is where my personal Kraton 6S is at currently, its nearly indestructible, thinking about possibly going full-blown stage 4 someday]

Stage 4: "Alpha and Omega", "The Strongest RC Car in the World", "The Second Coming", "The Wrath of Cthulhu": Welcome to the ultimate 6S RC build, an absolutely stupidly overpowered machine that most will say "Defies the Laws of Physics". Im striving to get here someday, and make my Kraton the ultimate RC machine, with no equal. So, here we go, one last time...
  • Completed Electronics Upgrade - Even though the stock BLX185 ESC is capable of the same 6S we intend to continue running on, the new motor draws too much current for it, and it will fail over time. So, HobbyWing MAX-6 it is, and the motor it will be driving is nothing short of insanity - the TP Power USA 4250 Series 40x83mm 2100KV (3Y Winding) motor, actually rated for beyond 6S LiPo (29V). This motor has about 40% more power output than the stock motor, while maintaining near-stock RPM levels. You could go with a full-blown 8S conversion but that will massively weigh the truck down between the massive motor and twin 4S LiPos. So I believe this is the best way to go. This motor might even take 8S if you want to try it out (only slightly over rated voltage, some people run Traxxas 3S motors on 4S and they work just fine). EXTREME CAUTION: This brushless system will destroy all but the most powerful LiPo batteries. Most people are aware that LiPo "C" ratings are false and useless, and I can tell you from research that it takes some of the highest quality, expensive batteries to run a system such as this, that is likely to draw nearly 120 amps under acceleration on high traction like asphalt. For that reason, I cannot recommend this system to anyone who intends to run it on anything lower than a 6200 mah 70C battery. The capacity is what matters most when it comes to amperage output on a LiPo, followed by internal resistance of cells, so do your research and get a high end battery over 6000mah for sure! - $270 (NOTE: Pair this system with 16T-18T pinion on 6S [stock tires] for absolutely insane speeds)
  • Its time to finish off the aluminum diff cups, get the other 2 for the front and rear diffs to combine with your already upgraded center diff - $60
  • Hot Racing aluminum Shock rod ends for all 4 shocks - $35
  • Hot Racing Aluminum Bulkhead covers front and rear. With this much power on board, the diffs are going to start moving ever so slightly inside their homes, you will want to eliminate this with solid aluminum, but there may not be a need to change the inner halves, as they are protected from damage by other parts such as the shock towers and braces. So start with the outer halves, and upgrade from there as necessary - $50
  • Hot Racing Aluminum center diff mount/housing and cover - be sure to get the open top edition of the mount and the cover that includes a small piece of red aluminum - this will retain your easy center diff access. This will eliminate any play in the center diff mount and reduce driveshaft shaking under load - $50
Stage 4 Total Cost: $1320 ($135 Stage 1 + $320 Stage 2 + $400 Stage 3 + $465 Stage 4)

Optional Upgrade Notes:
To run massively wide tires like ProLine MX38s, you will need the JBIRC wheel extensions, because otherwise the tires will rub on the body and chassis during hard cornering. the +10mm 17mm set will work for the new belted tires, while the +20mm 17mm set is best for non-belted. - $50
Dusty Motors cover recommended no matter what your build - $35
Use the tool below to determine your LiPo's true capabilities. As a helpful note, cheap batteries like Zee come BRAND NEW with an internal resistance (IR) of around 4.0-5.0. Decent batteries like SMC and Gens ace hang around 2.5, but can be as bad as 3.0. High-End expensive racing packs such as Protek Graphine are usually around 1.8-2.0, but can be as low as 1.5 (VERY RARE):

Last edited by wallacengineeri; 03-26-2020 at 02:28 AM.
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