1/10 ECX Ruckus 4x4 Build

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95PGTTech

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a couple years ago my friend bought me a RTR 1/10 2WD ECX Ruckus. he was into RC, I was not, and I had badly broken my leg in a motorcycle accident and was looking at years of reconstructive surgeries and downtime. Quite frankly, I was depressed and borderline suicidal. It turned out to be a good way for me to exercise my 2 big dogs despite my limited mobility, I put an Arrma 12T brushed motor in it and a better battery and it went back in the box after about 2 years when I started to make serious strides in moving again.

Fast forward and my son just turned 3, we are cleaning out the attic and I see the box, it's been up here for years I need to take this down and get rid of it but figured maybe he'd like it. He had no idea how to drive it, but he thought it was *HILARIOUS* to chase it around and have him chase it. I would throw a ball and he and Ruckus would run to see who could get the ball first. He still talks to it like he thinks it's a dog and it comes to the park to "walk" the trails with us just like our 2 dogs. I have an extensive history with modifying and racing 1:1 cars and motorcycles (how my injury occurred), and when I realized it couldn't outrun the dogs, started modifying it. It is now a 3674, 10bl120, fully built rig on Prolines. His grandpa is a big slot car racer and custom painted/stickered a Paw Patrol body for him.

Build thread here:
https://www.ecxforum.com/threads/95pgttech-1-10-2wd-ecx-ruckus-build.3270/
83 posts and a couple hundred pics if you're bored
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He started driving, and we quickly realized the limitations of a 2WD truck for what we do (grass). I was really leaning towards a Slash 4x4, but a good deal came up for a very rare 1/10 ECX Ruckus 4WD. The body is maybe his favorite part of all of this, so I did a few YouTube searches, saw it did pretty well back in the day head to head against a Slash, and bought it. Boy, did I not do enough research into the aftermarket for these things. Being that ECX got shut down a few years ago, and there were so few 1/10 4WDs produced in the first place, there is quite literally a handful of parts out there for this thing. We did some basic aluminum parts as we could find them (knuckles, hubs, etc) and basically just threw a good 2S in it and drove it, and LOVED it compared to the 2WD. One day, he got it stuck in high grass and just laid on the throttle and ended up sending a front CVD to the moon. Completely unavailable. No amazon, no eBay, no ECX forums, no FB groups, no alibaba, nothing. Shelf queen.

We tried a few CVDs from other 1/10 RC based on exploded diagrams and the little information available, but no dice. We also tried combining parts from each, no dice. Eventually I made the call to try and swap to Slash telescoping axles like we had done in the 2WD. What we ended up eventually doing was using Slash spider gears and planetaries inside the ECX differential and the ECX differential housing to get the Slash style diff output. Which then allowed us to use the Slash axle, but that required the slash knuckle, and caster block, and control arm, and and and and and...it ended up being a 3S 100c max 10 SCT 4000kv on Proline Badlands. The only remaining stock parts on it are the chassis, the diff housings, the slipper clutch, and the body posts. We started chasing speed, our best on grass was 42mph while shredding a ring and pinion, put a 4S in it for awhile, and just blew stuff up...an ESC, a motor, slipper clutch, and then differentials. More parts that are unobtanium, and back to shelf queen, and back to driving the reliable wheelie monster 2WD every day.

Build thread here:
https://www.ecxforum.com/threads/1-10-4wd-build.3326/
100 posts, pic intense
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Which brings us to where we are at today. I have to get rid of the differentials in their entirety. Ring and pinions simply aren't available anymore, and the damage suggests it's a metallury issue. A few older threads show this has been a problem from the start for these on 3S. I also have to get rid of the slipper that we've been fighting every step of the way - we think we solved it by doing some machining and converting it to a triple disk, but if this one were ever to break a replacement simply doesn't exist.

After a few weeks of research (literally every commonly commercially available 1/10 and 1/8 parts diagram), and ordering *literally* ten different differential housings to see what could fit this chassis, we've decided on Traxxas stuff. Nothing was even remotely close to the bolt hole pattern of the chassis, so it really became what fits dimensionally the best and redrill it. I had to slightly modify the chassis and bolted slightly modified XO-1 front and rear bulkheads, to which standard Traxxas 4x4 housings mate. I have an Arrma 6S motor and center diff mount on hand that is the frontrunner for that job, I'm waiting for some parts to get in so I can locate the center diff in such a way I can use off-the-shelf length axles. The reason I'm moving the build thread focus over to this forum is I think I've "outgrown" the ECX forum both in terms of lack of activity and there is so little ECX to this thing anymore that the experience of those outside that brand would probably be more helpful.

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95PGTTech

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The ECX nose/skid plate holes are pretty close to the XO-1 front subframe holes, just need to be slotted just a little. Note that the front set of holes on the ECX skid plate is for the bumper, so we are aligning to the second set of holes as the Traxxas diff housings and the ECX original diff housings are for all intents and purposes the same size. I have a countersinking bit I used after slotting the ECX holes 1mm each.
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I had to knock off two bolt hole bosses on the front of the ECX chassis that used to bolt the nose/skid plate to the front of the chassis in order for the XO-1 front subframe to sit tight. No other mods to the subframe were needed. With the two bolts installed and the subframe where I wanted to I used some blue tape, outlined the subframe with sharpie, centerpunched the holes and drilled them to 4mm and countersunk them. Old 2 holes in center, new 2 holes are the tiny 2mm pilot bit shown here.

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I think we nailed it. The two screws that effectively got deleted are replaced now by larger ones. I was going to mill down some of the XO-1 rear part of the subframe to get the control arm mounting points to sit a bit more level, but looking from the side profile the steering pivots are almost perfectly vertical which makes me think Traxxas wanted this upsweep built into the control arm angle. The same occurs in the rear, just reversed. Here is what it looks like with some pins and spare Slash 4x4 arms I had from RPM.

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Rear diff housing (they are different, and cannot be swapped, nor can the two clamshell sections be interchanged, I tried) mounted to rear XO-1 bulkhead.

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Before deciding to go ahead and modify/mount the front subframe I did try this rear housing/bulkhead on the front of the Ruckus. It could be made to work, but I didn't like it as much as I liked the front on the front. The upside of the rear is it uses a bigger bearing on the differential input (pinion). See the bottom two holes to the bottom front of the bulkhead, this is the kind of slotting I meant. Soooo close. There may be 2 or 3 of these chassis left and this guy is cutting up a brand new one lol.

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The rear Traxxas bulkhead I did modify, there were two bosses on the front bolt holes that I knocked down to get the smooth/level surface you see here.

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(combined posts)
Decided to move along with the Arrma 6S motor mount setup. The XO-1 would be nice, but then I'm limited to a slipper clutch and I don't have the best relationship with them. Not to mention I already have a lot of the Arrma pieces and a center diff on the way, whereas the XO-1 I'm going to get nickled and dimed to death. Both are probably the most impressive 1/8 scale setups I came across - I needed something that mounted to a flat plate bottom chassis and I wanted an integrated motor and diff mount. Both have aluminum aftermarket alternatives and dual motor options. The big appeal of the XO-1 was that it would be continuity of parts to use all XO-1 driveline, but because of the wheelbase difference that just isn't possible at minimum the center driveshaft is going to need to be custom.

Stuff should be here tomorrow to get it back to a roller status, and differentials are on the way. I'm hoping to be able to get the drive cups on the differentials and the center diff and then measure for driveshaft lengths and be able to find two from other RCs that are sufficient. In a dream world, I'd be able to mount the motor perfectly centered F/R in the chassis and run equal length driveshafts.

I'm still curious to see how much the higher LCA pin point affects overall ride height. Comparing it to the old chassis, the LCA pin is 20mm higher give or take. If this setup ends up working out well, maybe it will be worth exploring 3d printing new, smaller profile bulkheads to mate chassis to diff (and make the holes line up without having to redrill!). Overall, I'm happier. My brain has moved on from is this thing going to be able to be saved? to its just a matter of time and finding the right parts to save it. No one said going fast on this platform was easy.


(combined posts)
I also knocked the boss off of the factory ECX rear of the chassis that helps locate the ECX diff housing

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95PGTTech

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Same process, got the first two that are close done, then the other two need to be completely custom drilled. The factory XO-1 says the diff housing bolts for the rear are m3 x 12 (m4 x 12 front), but I'm not sure how comfortable I am with this by the time I needed to slot and then countersink.

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I ended up drilling the Traxxas rear bulkhead holes oversize to 3.3mm and then tapping m4x0.7 and using m4 hardware like the front. I'm much more comfortable with this.
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Here is the two of them together. Now that these are mounted and I've "chosen" this route over other diff housing options, I put an order of XO-1 stuff in from Jenny's. steering setup, braces, links, strut towers, etc. Bonus to this route is a lot of the slash 4x4 from the old chassis will be able to be swapped right over to this, most of it is interchangeable (versus if I went with the Arrma or the MT10 setups, I would have had to order entirely new front and rear suspension kits to fit them).
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As best I can measure it, axle centerline to axle centerline at the housing is equal each side, the cross diagonals are equal so these are square to the chassis. Axle to axle is approximately 5mm greater than the old build (not to be confused with wheelbase, which is measured at the hub, but they roughly correspond). I had intended to just mock these in and then figure out other mounting and kinda put it all in at once, but there really isn't much choice on where to put these front to rear. I'd rather not be as close to existing holes as it is.

Next I need to get the front and rear suspensions on so it's a roller again, and figure out the driveline. I haven't decided between the Arrma 6S setup or the XO-1 setup yet, but it will probably be determined by what's available as far as dogbone lengths out there. Yes, I'm obviously going to have to cut the poop out of that center tunnel. The upper chassis spine is a complete no go because it mounted to the differentials, for starters. I will be making a tower to tower brace and tower to chassis bracing. I ordered the XO-1 brace, it will be far too long but I may be able to use it as a starting point.
 
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95PGTTech

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Decided to move along with the Arrma 6S motor mount setup. The XO-1 would be nice, but then I'm limited to a slipper clutch and I don't have the best relationship with them. Not to mention I already have a lot of the Arrma pieces and a center diff on the way, whereas the XO-1 I'm going to get nickled and dimed to death. Both are probably the most impressive 1/8 scale setups I came across - I needed something that mounted to a flat plate bottom chassis and I wanted an integrated motor and diff mount. Both have aluminum aftermarket alternatives and dual motor options. The big appeal of the XO-1 was that it would be continuity of parts to use all XO-1 driveline, but because of the wheelbase difference that just isn't possible at minimum the center driveshaft is going to need to be custom.

Stuff should be here tomorrow to get it back to a roller status, and differentials are on the way. I'm hoping to be able to get the drive cups on the differentials and the center diff and then measure for driveshaft lengths and be able to find two from other RCs that are sufficient. In a dream world, I'd be able to mount the motor perfectly centered F/R in the chassis and run equal length driveshafts.

I'm still curious to see how much the higher LCA pin point affects overall ride height. Comparing it to the old chassis, the LCA pin is 20mm higher give or take. If this setup ends up working out well, maybe it will be worth exploring 3d printing new, smaller profile bulkheads to mate chassis to diff (and make the holes line up without having to redrill!). Overall, I'm happier. My brain has moved on from is this thing going to be able to be saved? to its just a matter of time and finding the right parts to save it. No one said going fast on this platform was easy.



(combined posts)
Parts from JennysRC arrived. Great first experience dealing with him. Fixed a last minute change order, fast shipping, excellent packing and organization.
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Comparison of the tower-tower braces shows how much more wheelbase the XO-1 has - and therefore why I can’t just bolt the entire XO-1 drivetrain in. I’ll keep the brace though, I may just section it and weld it back together.

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Arrma 6S center diff mounted
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XO-1 rear shock tower. I’m not too keen on these standoffs after seeing them in person I’m going to get a slash tower built for bashing
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Slash ultimate diff. It’s just what he had on hand, this will get XO-1 diffs and aluminum housings and what not, I’m just trying to get stuff mocked together. RPM arms, XO-1 pins
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Started stealing parts from the old donor rear - GTR xxl shocks, VG racing springs, eBay hardened steel axles, slash camber rods, XO-1 hubs, brass 8mm hexes.

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All together on the “new” chassis
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Another issue…nothing captures the rear of the hinge pins they can just slide out. On the XO-1 it’s actually part of the rear diffuser. On a slash it seems to be part of the rear bumper, which mounts to the top of the diff so it should work. I’ve heard the RPM bumpers are good, and I’d like to run. wheelie bar again. Time to do some digging.
 
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95PGTTech

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One thing I've been working on is the rear diff input - unlike the front that leaves the stub of the pinion outside the case, the rear just has a huge bearing and the pinion is a female and accepts the back of the shaft of the slipper clutch (or optional center diff). I have another front pinion, and both ring gears are identical, but the outside diameter of the pinion is 6mm and the bearing race is 18mm. My solution was to put a 6x11 bearing inside a 11x18 bearing, and sandwich them between two 18mm OD washers (I forget what the original ID was, but I drilled them out to 6mm.

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I ended up putting it back and forth together a bunch of times and I ended up adding another 6x10 shim underneath the pinion to get the R&P mesh a little tighter to where the in and out endplay of the pinion matched the front.

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I got a set of Arrma (aftermarket knockoff) diff cups and drilled them out to 6mm ID. the hole in the stock Traxxas pinion isn't big enough to accept a set screw from the Arrma diff cup, and I'd like it to sit closer to the housing than where the hole would line up, so I think I'm going to end up cutting this pinion down and just putting a new flat on it to accept a standard set screw setup. On the ground, what I have now rolls pretty smoothly. I have zero clue how much freeplay the dogbone that goes into this cup should have, I know from previously with the ECX it shouldn't be bottomed out tight.

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So the point of all that is I can now transfer power from an Arrma 116mm dogbone to the center diff setup I want to use. Once I finalize where it's going to live, I'll cut out that section of the center tunnel so I can mount it flat on the chassis. I picked this for now because it puts the motor as far forward (front left) as possible. I did some quick measurements and ordered a 102mm shaft for the front. I'll try and cornerweight it when more parts get here but I can't see a scenario where putting the longer shaft up front and moving the motor and center diff more backward actually helps me. Getting that weight forward was really the tiebreaker between going this way or doing a XO-1 style setup with a slipper/center diff right off the rear diff and the motor mounted back there. I ordered a Tekno RC big bone center shaft kit too so I can see their diff cups and if I could make them work.

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95PGTTech

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Front steering/subframe/diff as received from Jennys, installed, shock tower

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The old donor setup from the last version of the 4x4 Ruckus

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One question I have is this area on the front steering brace seems like it would be ideal placement for a sway bar, but the XO-1 exploded diagram does not indicate the vehicle has one. I can't really see in videos of anyone having one, anyone have any idea what this is for?

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Hung the arms, it looks like there should be plenty of suspension travel if I can get the shocks set up on it right

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Other than I can't get the inner axle shafts off the old differential (the little 1.5 allen screw the tool broke off in it on both sides!), front went together well. With the suspension at full droop, because they are a universal joint design there is some binding, so I'd really like to get away from them anyhow, but I need to get them on here at least for mockup. I'll probably just take the easy way out and go with XO-1 shafts for now, but Tekno is also an option since I have 6mm capable hubs front and rear.

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95PGTTech

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I weighed the old chassis with the battery, motor, motor mount, steering servo, etc. on it and put some batteries on the new one that matched the same weight to get some idea of what ride height may be when loaded. I'm not terribly upset, but it definetely gives up ground clearance over the old setup.

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The center differential is in approximately the final location, so I cut out some of the tunnel to start getting an idea on driveshaft angles and how much more cutting I'm going to need to do. The motor is going to be located in the front driver side section. Battery size and placement will be the next major hurdle. I want to begin with at least 4S on this. Clearancing for the big ring gear on the center diff is going to be needed unless I can find a smaller one. Removing this obviously introduced a slight amount of flex to the chassis, which I'm hoping will be removed with a brace between both towers and the center diff.

EDIT: Found a 46T spur, ordered it. I'd rather not have to cut the chassis to clear the spur and have it sticking out underneath. The spur was also the thing closest to the battery during mockup. I'm sure I will be able to adjust through pinion selection.

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Front and rear slash shock towers arrived, installed. They are MUCH thicker than the XO-1, but I need to work on the offset of the shocks in front...they hit the big camber rods. The XO-1 has huge offset spacers to clear this.

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The Arrma 46T center diff spur gear came in too. I was excited, it was 4mm less diameter around and thought it would work great...until I took it apart and realized it won't work. After much digging, I think what I was sold as a 6S BLX (regular) diff is actually a 6S EXB diff. Completely different bolt pattern, much larger output drives. The only anything I can find for an EXB diff is a 44T in China. Whatever, better than cutting up the chassis more and having the spur sticking out underneath I guess.

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The RPM rear bumper also came in today, but after going 0/2 I think I've had enough pain for one day. Oh, the joys of custom.
 
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95PGTTech

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102mm came in, it's pretty close to fitting just laying everything in there, so I marked out the location of the center diff and got to cutting.

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I didn't have a lot of room to miss drilling holes so I made a template. Really helped. Countersunk m4

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Used the XO-1 offsets on the Slash shock tower, best compromise I could make. Offset the bottom of the shock too to give those big camber arms a little room to work

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All in and seems good, but driveshafts feel a little tight. Don't sit all the way into the cup on the center diff but I guess it's supposed to be like that (unmodified center diff to unmodified driveshaft)

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Front and rear have maybe 2-3mm free play, didn't really sit into the diff cup all that well because of how far the Traxxas output shaft sticks out into the center of the diff cup, so pulled them out and got to work. Drilled new bosses for the set screws. Re-shimmed the rear again, when I had tightened up the case I didn't like the mesh anymore, happy now. Rolls freely without binding or noise now.

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95PGTTech

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RPM rear bumper went on fine except for the bottom mount (the one that holds the hinge pins in LOL). It needs to go where the XO-1 subframe is, so I'm going to need to remake the lower mount myself.

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Clearanced the left rear corner to start fitting stuff. Got the GNSS box mounted and the chassis notched a little so I can plug in to charge it without having to remove it from the vehicle. Cleranced the center tunnel a little more for the rear driveshaft.

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Just a follow up on parts that took longer to get here. EXB diff cups don't work either (out of the bag directly) they are 5mm but in a D shape so it would actually be harder to drill them out than the BLX ones I used. Tekno RC ones for the Slash won't work, they accept a 6mm dogbone not the 8mm dogbone of the arrma. It would be neat to not have to modify the slash pinion shafts like I did, but even if it did work it would be real close on driveshaft length. I did learn from them they use an o-ring which I may end up doing on the Arrma cups. Scorched makes a 6mm bore 8mm shaft cup, but its going to take a minute to get across the pond.

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Changed up the GNSS a tiny bit to give more clearance to other components that will need the space.

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More cutting up of the OEM chassis, this time to mount the steering servo. It was either this, or mount it outboard behind the right front tire (and to make matters worse, the wiring harness would be facing forward).

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Searched far and wide for an aluminum mount that I liked, finally found one from Redcat. It's listed as an Everest-10, I've never even heard of that model. I had to trim the servo just a tad to run this "reverse" mount. Originally I was going to cut the tunnel more and run the bracket underneath the servo to the center, but this way kept me from having to cut more and it kept the bolt holes in the meat of the chassis - mounted to the center it would have been very close to the already cut out tunnel. I have a 20kg servo on the way, my wires are too short from the old setup for this one. I'd also like to manipulate the horn a little more to get the steering arm as parallel to the chassis midline as possible. The arm I just stole from the old build - hey, an actual ECX Ruckus part! LOL! (well, actually, an aftermarket upgrade replacement of a stock ECX part, but I digress). I had to countersink the mount right out of the bag, they used button head screws that wouldn't allow the bracket to fit flat against the chassis.

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Trying to get everything neat and organized. That's a 3S battery, my 4S won't fit until the new spur arrives. It does clear, but we are talking a couple sheets of paper of clearance I don't want the battery and the spur going out on a date. 3S will be more than enough for test drives. I don't think that receiver location is going to work, I plan on running a 74mm long motor (that's a 50), but again, for a first test drive it's fine. Front driveshaft to steering servo clearance is excellent, something I didn't think of until reassembly but got lucky. On the bench, steering works well. Had to turn it down a bit with the endpoints, hence part of the reason going down to 20kg. 25kg was a little "twitchy" on test drives.

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95PGTTech

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Got the steering finished up and took 4x4 version 3.0 for basically the same drive I did for version 2.0 when I redesigned the suspension and driveline…like a grandma. Nothing flew off or failed catastrophically, which is a huge win. Now comes the process of looking everything over, figuring out what needs reworked, and buttoning up everything not done.


Yeah, I wanted to rip it. But I have no wheelie bar on it, no loctite on a single bolt, no fluid in the diffs, 4 axles that seem like if I look at them wrong are going to the moon, and in most cases 1 bolt where 4 are needed.

I’d be really interested in seeing if there is any differences in the drivetrain. Same battery, same tires, same motor and ESC - and see if there is any speed difference. I’ve long suspected I was losing a lot in the ECX slipper and diffs
 

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One major problem noted from the test drive was the double bearing setup on the rear diff did not work. Not surprising. No one makes a bearing with the ID and OD necessary to run one bearing here. The outer bearing walked, which make for a lot of side to side eccentric motion as the diff cup rotated - not bad enough to cause an issue at a walking pace, but if I send this thing 50mph, it's going to shoot parts across the lawn. I changed up the shim setup to use a larger outer diameter washer to hopefully prevent this problem from occurring again.

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I have still been ordering differential cups trying to find a 6mm input shaft/8mm driveshaft setup. I think this one was from a Revo, measured 7mm on the input shaft and 10? on the driveshaft.

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20kg servo arrived. xacto knife indicating the point i was talking about needing to be removed to run this in reverse mount like i have it.

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RPM wheelie bars arrived. Still useless until I can figure out a bottom mount solution for the rear bumper

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95PGTTech

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one of the last major pieces that need to be fabricated was a tower-to-tower brace. the stock ECX 4wd has an upper chassis "spine" that has two bolts to each diff and a series going down the center tunnel and the driveshaft rests in between (kinda like a slash). Obviously I can't run that. On top of that, I cut a lot of strength out of the lower chassis making room for new components.

I hadn't intended on it going this way, but I just chopped up the XO-1 brace to start taking measurements and get a starting point and it evolved from there. The overlapping actually nicely accounted for the front diff being slightly taller than the rear one.

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I tried to be super cute and drill and tap the two of them together, but my HF quality m4 tap decided to break off in a hole. Just being a mockup/trial piece, I said screw it, left the broken tap in it, and through-bolted some other spots.

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One thing I really wanted to do was tie in the motor mount/center diff mount. Space is a premium, and although I'd like to, I'm not sure I'm going to have the room to run a tower-to-chassis brace at each end. By ditching the stock Arrma plastic center diff cover, I'm able to get a piece of aluminum in there to act as a diff cover and bolt to the new spine. Significant clearancing of the new piece necessary to clear the spur (smaller diameter 44T is on a boat in the Pacific somewhere).

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not sure how well you can see it, but the center diff does not have adequate bearing support/races because of changing the top plate so it moves around under power. ordered https://www.amazon.com/dp/B09MS3LWJT?psc=1&ref=ppx_yo2ov_dt_b_product_details to try and resolve this. Eventually, I'd like to use a complete billet adjustable motor mount/center support setup like the one from PPS-RC, but I've learned the value of mocking up with cheap Chinesium parts.

Regardless, even with just two bolts out of the four from the center diff/motor mount brace to the new spine/upper chassis/tower-to-tower (whatever you want to call it)...WOW...stiff. Not only took all the flex out of the two diffs at the end of the chassis, completely eliminated any of the twisting action that was so apparent after removing so much of the stock "tunnel."

I'd really like to run a complete one piece center diff support like this
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but these only seem to be available for the older kraton versions and not available in the size I'd need for a v5 exb.


next steps are to get those bearing supports in when they arrive, drill the other two holes for the center support, then blow everything apart and reassemble with proper hardware, loctite, and lubrication in preparation for an actual test drive. additional bracing and body mounts are on the fabrication list, but won't prevent moving forward at this point. front and rear bumpers as well. I'm leaving the axles be for now, I still haven't decided if I want to stay something telescoping like MIP or the XO-1, or just go all out for the Tekno fixed length dogbones - they *should* work, I'm using stock-length Slash arms.
 
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Greywolf74

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Its hard to be interested in a post like this when you can't click on any of the pics and view them because they are all links to another forum that you have to be a member of in order to view them. Maybe next time actually post the pics themselves on here instead of linking to another forum.
 

95PGTTech

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Its hard to be interested in a post like this when you can't click on any of the pics and view them because they are all links to another forum that you have to be a member of in order to view them. Maybe next time actually post the pics themselves on here instead of linking to another forum.

Sorry guys, since I’m a member I can’t see that. Lame, it’s a sister forum in the same network. I’ll try to move them over with posts starting tonight and then go back through

The YouTube videos show/link ok?
 
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