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Old 07-19-2015, 10:24 PM   #1
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Default Build Complete: Arrma Raider

This one's actually been done for a while, but my brain has been in summer-vacation mode and I haven't felt like doing a writeup.



My RC builds generally fall into 2 categories: "What do I need to do to make it handle the way I want?" vs. "What do I need to do to make it survive reasonable use?" The approaches I take to solve those problems also generally fall into 2 categories: "What do I have to adjust to make it work right?", vs. "What do I have to upgrade to make it work right?" This build was very much the second type in both respects -- "What do I have to upgrade to make it survive reasonable use?" It handled very well out of the box, the only handling-related change I *needed* to make was finding better tires, but stuff just kept breaking over and over. So this build was really about replacing cheap parts with better parts, until I got it to where it didn't break every third time I ran it.



The first order of business was replacing the gearbox. The metal-geared BLX version of the Raider has been discontinued, so I bought the plastic-geared BLS version. Rather than wait for the plastic gears to fail under the BONE-CRUSHING POWERRRRR of the brushless motor, I opted to buy a Granite BLX chassis and cannibalize the metal-gear gearbox from it. I was also able to cannibalize a few other parts that were interchangeable, including spare shock-tower parts and a Heavy Duty suspension-pivot kit, but the gearbox was the really important bit.

The Granite chassis arrived with the diff output gears already stripped, so I ordered a rebuild kit and rebuilt the gearbox from the ground-up, with waterproof grease on the gears, 100K diff oil inside the diff, and a Raider-appropriate 32-pitch 54-tooth spur gear. (the Granite uses a 57-tooth spur gear.) I also threw on the shiny red optional motor-mount plate, because it was pretty. The motor is a Tacon 4000KV, pulled from my HPI Savage XS because it was too fast for that vehicle. It moves the Raider just as fast, possibly even faster, with 17/54 gearing, but because it's a buggy instead of a monster truck, it can actually handle the speed safely.

There was some doubt at first about whether the older metal-gear gearbox would fit on the newer chassis, but fortunately Arrma didn't change the gearbox mounting points. So I got the benefit of the older gearbox *and* the benefit of the newer monocoque chassis. (the older chassis had the servo box as a separate piece which required the metal TVPs on the sides to keep it attached, whereas the newer chassis just uses the TVPs as optional reinforcement.)



I also replaced the rear axles. I suppose the stock dogbones were okay, but I really prefer the more-predictable outdrive wear produced by axles that are firmly attached at one end. (I wouldn't mind sliding X-CVD-style axles either, but they're not available for this vehicle.) Once I found out that Arrma is part of the same company as Team Durango, I started checking out Team Durango's vehicles to see what would fit; as it turns out, the 61mm rear axles for the DEX410 are a drop-in replacement for the Arrma Raider's dogbones. I chose the universal-joint style instead of the CVD style, because universal joints are less prone to premature wear from grit, and these axles articulate through such a narrow range of angles that the U-joints' inferior rotational smoothness when spinning at an angle isn't an issue.



Fitting the Team Durango rear axles moved the positions of the drive pins closer to the hubs, and while the stock slip-on hexes could still mesh with the drive pins, it wasn't very secure, and also having the drive pins close to the hub meant I could entertain the idea of using locking hexes instead. (I hate it when slip-on hexes fall off when I remove a wheel.) After scouring the internet for two different-width hexes (the front hubs use 4mm-width hexes while the rear hubs use 6mm hexes), HobbyKing came to the rescue with hexes in both sizes in a color that matched the rest of the optional aluminum hardware. The quality was hit-or-miss, but a pack of four hexes was only $3, so I ordered several packs of each and managed to find a pair of front and rear hexes that fit just-right.

Before I move on, let me say that the DuraTrax Bandito tires are fantastic pavement-pounders. They wear well, they look great, and as the rubber gets scuffed-up it actually starts to take on a gummy texture, unlike Pro-Line's tires, so they continue to grip really well even once the shine is worn-off and they're covered with pavement dust. I actually noticed these tires getting warm after use, something I never noticed with any other tires. I was planning to run Pro-Line Road Rages or Trenchers on this buggy, but after trying the Banditos I'm now considering using them on my MERV as well, which currently runs Pro-Line Trenchers. I like them that much.



Having sorted out the drivetrain, the remaining issues were: Front shock tower stiffness, shock caps that popped loose every time the buggy flipped, and significant scraping on the rear shock tower. The picture above shows my latest and (thus far) most successful attempt to deal with the scraping problem: I drilled some holes into the top of the shock tower and fitted some very short button-head screws into the holes, to act as sacrificial (and replaceable) contact points when the buggy goes wheels-up. They occasionally get torn loose and I have to replace them, but that beats having to replace the rear shock tower multiple times a year.



The front shock tower has been more problematic. Being a rear-wheel-drive buggy, the Raider's front shock tower is castered backwards at a sharp angle, which means that the shock-mount screws are tilted upwards at an equally-sharp angle -- perfect for digging into pavement when the buggy flips over, and either bending things or breaking the shock tower outright. The buggy is currently on its third front shock tower, and I've only owned it for a couple months. However, I think at this point I've finally got it stabilized enough that it won't keep snapping over and over. Part of the solution was to get the optional red-anodized aluminum brace, which helps prevent the shock towers from being squeezed together when the shocks compress -- and really, the optional plain aluminum brace should be standard equipment on this buggy because the shocks don't even fit properly without the brace installed.

Another part of the solution was capping the shock-mount screws with acorn nuts so there's a rounded surface to skid across the pavement, and the last part was to build a *second* brace that fits behind the shock tower to reduce flex even more. The second brace is constructed of an M3x30 grub-screw with two Dubro 3mm ball-links attached to it, adjusted so the center-to-center length of the brace is 1mm shorter than the natural spacing of the shock-mount holes, so the brace is always in tension and ready to resist even the tiniest amount of spreading. I had concluded that most of the failures were actually caused by the shock towers twisting before breaking, so anything that keeps them from twisting helps immensely.



While I was in the middle of testing all this (fortunately before I bought expensive shocks), I managed to lose control of the Raider and crash it head-on into a car tire -- not the side of the tire, but the tread surface, so it was jammed into the ground. It snapped both the upper and lower front-bulkhead plates like...well...plastic, and destroyed the front shock tower, but at least it didn't damage the steering or the nose of the vehicle. (I had already replaced the stock steering servo with a Hitec HS-5645MG, so if that had broken too it would've cost $50 more to fix.) Suddenly the reason for the optional aluminum lower-front bulkhead plate became obvious. So I upgraded that part as well, and while I was reassembling the front of the vehicle I found little nooks and crannies to stuff about 2 ounces of lead ballast to improve traction on the front wheels. I haven't crashed it into any more car tires yet, so I can't say for sure if the aluminum lower-front bulkhead plate is better, but if nothing else it should at least be re-bendable if it gets bent in a crash.



The last problem I had to deal with was the shocks. (of course, I didn't actually deal with these problems one at a time, more like a little bit of each all at once, but it's too confusing to write about it that way.) The stock Arrma shocks are, in a word, crap. They can be fitted with HPI shock diaphragms to keep the oil from frothing, and I did that for a while, but there was nothing I could do to reduce the leakage around the lower O-rings or to keep the caps from popping off in crashes. Since I knew Arrma was owned by Team Durango, and I'd seen some teaser pictures of red-anodized Arrma upgrade shocks that looked strangely like Durango shocks with different anodizing, I decided to focus on the shocks Durango has to offer. I bought several pairs and carefully test-fitted them so I could return the ones that didn't fit.

Eventually I settled on the 23mm-stroke Big Bore shocks in the front, and the 29mm-stroke Big Bore shocks in the rear. The dampers themselves were a huge improvement, being made of much better-quality materials, but unfortunately I couldn't use the original springs, and the springs that came with the Durango Big Bore shocks were not at all suitable for the vehicle I was actually installing them on. I took a trip to my LHS to see if they had any springs that would fit; all they had that came close were Team Losi Racing springs, so I bought front and rear spring-tuning kits and took them home. I figured out which springs were the closest match for the stock springs (or rather, the stock front springs, and the stiffer rear springs that I had cannibalized from the Granite chassis I'd bought), and tried them on. They were close, but they were a bit too wide and they wobbled a lot. In a moment of lucidity, I decided to try putting some heatshrink around the end-coils of the springs, and I discovered that two layers of heatshrink was just enough to make the TLR springs fit securely on the Team Durango shocks.



Despite being wider than the Durango Big Bore springs, the TLR springs still juuuuust barely clear the upper-front Y-arms, and just barely is good enough. I might someday buy the Team Durango equivalents for the TLR springs I decided to use, but the handling is so much better with the Durango shocks and TLR springs that I don't really care right now.

There's one last feature that's been clearly visible in the previous pictures, but I've talked around it thus far: the lights. Yes, those are Axial light buckets, two in the front to replace the fake headlights that the Raider came with, and a third one installed on the back in a Mad-Max "wherever it'll fit" style. The taillight is off-center, but I actually like the way it looks that way; it gives the vehicle a little bit of a hacked-together "here comes trouble" kinda look.



They may look purely decorative, but for me they do serve a functional purpose. Many days I don't have time to run my RCs until near-dark or after-dark, especially when the days are short in late fall and early spring, so having lights on the Raider means I can run it whenever I have time. It's pretty cool to see those two little dots of white light hauling towards me at top speed; I don't know exactly how fast this thing can go, but it's definitely above 35mph, which is about all I have space for anyway.



Oh, one last thing: When I say the Raider handled well out of the box, I'm not being generous. Once I put the Bandito tires on it so it could actually get a good grip on the ground, I was basically done tuning the vehicle for optimal handling -- a little camber adjustment here, a little toe-adjustment there, the same stuff that has to be done on any vehicle -- but I didn't have to do anything major to get it to work well. As long as the tires stay on the ground, this thing handles brilliantly, and it did from day one. I put a Futaba GYC-430 gyro on it, because I dislike having to be careful about slamming the brakes on RWD vehicles, but I tested its handling with the gyro disabled and it was obvious the gyro wasn't doing any work except when I was making the Raider skid to a stop. If you're not lazy about learning how to drive an RWD buggy properly, you could buy a Raider, put some terrain-appropriate tires on it, and go have fun without having to wrench on it at all. All the other stuff I did was just a combination of personal preference and improving crash-survival -- not nearly as much of an issue if you actually know how to drive a buggy properly.
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Old 07-19-2015, 10:25 PM   #2
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Oh, I forgot to mention: The wheels are from the FTX Vantage, ordered from England. I'm pretty sure it's a rebrand of some discount-brand vehicle, but the wheels are strong and they have the right offset. Also, they're $5 a pair -- not gonna complain about that.
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Old 07-20-2015, 02:42 PM   #3
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Nice write-up The tires look good, I'm glad you found some decent rims. I like the brace on the shock tower, I'll have to remember that if I can find a Raider cheap enough. Also like the CVDs (universals), Glad to know they fit instead of the dog bones, I'll have to see if I can find long enough ones for my fury. Glad the shocks are working for you, did you add limiters to the inside?
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Old 07-20-2015, 03:41 PM   #4
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I did add limiters, though I don't remember exactly what length. I just compared them side-by-side with the stock shocks and adjusted the limiters until I got the fully-extended lengths to match.
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Old 07-20-2015, 05:56 PM   #5
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I don't suppose you know how much she weighs with a battery?
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Old 07-20-2015, 10:36 PM   #6
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Susprisingly heavy; just under 2kg, or 4lbs. 6oz., with a 2S 5000mAh hardcase LiPo. Has no trouble holding a wheelie with a two-pole brushless motor, though. Might be too heavy to race on dirt, but it sticks to pavement well enough that it still traction-rolls on occasion despite having such a low stance.

It doesn't look like it should weigh that much, but the funny thing is, just because it's got a narrow body doesn't mean it's lacking any of the necessary parts to make it run. It's all just packed into a smaller space instead of spread-out on a flat chassis plate. But that's the reason I bought it -- I love the way it looks.
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Old 07-21-2015, 08:37 PM   #7
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Man this thing is fun. I took it out for another run today; it corners so well. I don't have anything else I can push through corners as hard as my Raider.
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Old 08-15-2015, 11:50 AM   #8
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Any updates?
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Old 08-15-2015, 01:45 PM   #9
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Nope. Haven't had to do anything to it. I eventually need to come up with a better way to armor the top of the rear shock tower, but the screws are working well enough for now.
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Old 11-19-2015, 11:01 AM   #10
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you have a tutorial on how you install your lights?
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Old 11-19-2015, 09:31 PM   #11
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No, but it's pretty straightforward. I buy a pre-wired custom-spec light kit from RC-Lighthouse, cut the wires to the length I actually need and then re-solder the LEDs in-place (this still saves me the trouble of building the wiring harness from scratch and selecting the correct resistor for each LED), and then I plug the wiring harness into the Bind port on the radio receiver. I don't bother with a switching mechanism. The light buckets on this particular vehicle are actually from an Axial lighting kit; the headlight buckets are a bolt-in replacement for the fake light buckets that come with the buggy, and the taillight bucket is attached with a long screw that goes all the way through the motor guard. I painted the insides of the light buckets with Spaz Stix chrome-silver airbrush paint, but I just used a normal paintbrush to do it.
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Old 01-16-2016, 05:14 PM   #12
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Nice build man, I'm in the process of building mine also but I'm using a lot of your suggested upgrades along with some of my own. I will post it up once I'm done, but this project came to be quite costly. I'm running a Dynamite Fuze 4 pole system from the Vaterra Uno Glamis.
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Old 01-17-2016, 01:11 AM   #13
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Damn, I've had this thing for over six months now. Where does the time go?

Oh right, it goes into the two black-holes of work and expanding my RC collection.
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Old 10-15-2016, 05:20 PM   #14
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that Buggy is BOSS !!!

I have the raider xl mega, I disassembled it I need help with the front end reassembly and the servo area.
any phots or videos would be of great help. THE MANUAL IS OF NO HELP
Thanks ..
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Old 01-08-2017, 03:24 PM   #15
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Default Need help with dog bone

I'm new to the RC world and need help. Seeking a way to fix the too short dog bones on the Raider xl. Any suggestions?
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