CrossRc EMO XX - 1/6th UNIMOG - DUAL FUSION8's!!

[WRXronald]

Always a good time lol, until its not. Tried to make a vid today, didn't happen. Put together a set of tire chains, they're EPIC & VISCIOUS!!!! The snow got wayy too deep to go anymore so I needed more traction!

But I started yesterday getting this issue where one of the FUSION8 pinions is walking in on the motor shaft and off contact with slipper spur gear. It ate up a few mm of spur gear teeth (back to front, closest to transmission) but there's still enough beef left to mesh and get in some thrash before I need to upgrade to the carbon steel spur gear. But it happened 3 times today --- and I tore it apart EVERY single time to try and diagnose and repair, only for it to walk back again EACH time, and almost instantly.

By the 2nd time today I knew something was weirdly up as I already death with same yesterday, removed pinion, heated, dried, cleaned, loc-tite blue, and re-install. Its bites on a stock flat grind on the 5mm shaft from the manufacturer (very SMOOTH grind I might add, doesn't end up being a good thing).

So the set screws is fine, and not the issue, loc-tite is holding, no grease or anything in there after torching it --- it was the grind, too dang smooth on a seriously hardened shaft ---- I put a diamond file on the back of the set-screw the 2nd or 3rd time thinking it would help bite better, but not on the shaft flat (or not hard enough at least), and it still walked, almost immediately. Tightened it like a mother too, surprised I didn't strip the set screw.

By the last time of digging into it tonight, I finally bit the bullet, removed the motor from the transmission to better diagnose, ultimately the shaft was just so smooth the set screw keeps rotation in check on the flat, but not sliding up/down the shaft. This time I put a HARD grind on the shaft flat with a fine diamond file -- almost a small groove I would say -- for the set screws to bite deeper into.

Did a quick test run and no slippage so far --- tomorrow I thrash it again in deep snow with MEGA-CHAINS. Promise to get some footage.... It wapped a piece of ice at my face today when punching it in the driveway --- and i'd say almost darn near hurt - hit right on the cheek bone below the eye socket lol!!! YIKES!

 

[Gula]

Eye protection....from here on out? I looked at cross rcs models, and they have a 1/5 "scx" style truck in 4x4 or 6x6.... rad! Is this essentially the same with a different body?

 

[WRXronald]

Eye protection....from here on out? I looked at cross rcs models, and they have a 1/5 "scx" style truck in 4x4 or 6x6.... rad! Is this essentially the same with a different body?

Yeah I think its pretty much the same platform, just a pick up truck body set meaning they can call it 1/5th scale now whereas the Unimog being a much larger real vehicle is "1/6th" scale in the same essential sizing --- but I could be wrong the wheelbases ARE different --- the 6x6 pick-uip truck in 1/5th scale is LONGER than the 6x6 Unimog in 1/6th scale, I just don't think its justifiably wider or larger in tire size. I suspect the axles and transmission are identical, i'm nearly certain its the identical dual motor transmission with MOD 1 gears.

I laugh at the specs though -- still not a wider track width than my big truck builds (by a fair margin) and still not a larger tire than my big truck builds (by a fair margin). But 1/5th scale? Track-witch I think is to be 16inches on the new 1/5th's, and very long at something massive like 52inches bumper-to-bumper, iirc, on the 6x6 flatbed pick-up truck, naturally the 4x4 is smaller I think 25inch wheelbase/34inch bumper-to-bumper or something like that but both 1/5th scale Pick-ups including the 6x6 are a hair narrower overall than the Unimog at 15.2 vs 15.4 inches. Just looked them up. The 4x4 Unimog that I have is 15.4 inch track-width, 20.5in wheelbase, and 32in bumper to bumper, similar to the 1/5th pickup 4x4 My big rig builds each come in with 18in track widths, so.......... ya know, everybody keep trying.

And weird still that while the 6x6 XX2 pick-up truck flat-bed IS longer than the 6x6 Unimog, its payload length is considerably smaller so for instance the Unimog can carry the 1/8th scale X4 Gladiator or even an SCX6 as tight fit, but the 6x6 pick-up truck cannot due to short flat-bed with extended-cab.

Also, still using plastic spur gears. (mine is partially stripped already, fault on me though for a bad pinion install job).

Also, the Watts-link in the rear -- we should chat on it. Its COOL AS EFF, looking, but in real function, while it works, I find it seems to hinder free movement, especially on the rear passenger -- where it literally almost binds up your shock after a bit of use and needs a fair amount of tweaking to get smooth. I'd say maybe that's just the EMO XX I got, but I also have a EMO X 1/8th (this drivetrain I have BEATEN DOWN hard w/out much issue at all, a good sign) --- with a nearly IDENTICAL chassis/tranny/suspension setup, just smaller sized, and the watts link and rear passenger shock -- identical "sticky" phenomenon. But because watts link is SO cool and frankly the rear suspension linkage geometry is not effective on this truck w/out it (IE rocks to and fro w/out stabilization of some sort) I keep it in place.

So, pretty much just like the SCX6, its not perfect from a plastform perspective. I will say I have thrashed the drivetrain reasonably hard, not super super crazy, but hard --- and its taken eveything so far w/out much of a sniffle. REALLY HAPPY about that. Portal repairs, etc, crappy shifting diffs, etc, would be show stoppers and the EMO X convinced I should be good there if they just carbon copied into a bigger rig which is pretty much exactly the EMO line of rigs now. X2, X3, X4, X6, and now XX and XXL.

Call me picky I guess, overall yes i'd buy it again and its pretty much my now my prized RC (although if you saw the custom R35 body I've got on a 1/10 drifter all CF'd out, DROOL CITY my friends so pretty as a shelf queen, def a good rival!!).

I'm a CrossRC fanboy don't get me wrong, but there's a limit and i'm not shy in saying it. For $1500-$2k, you're still gonna work to make it work.

Usually that's part of fun, right?

 

[WRXronald]

Chains made the difference.... w/out, in this depth of snow, the rig goes pretty much nowwhere after the first hard push as it sits up on the belly and couldn't get traction to reverse out of the pinch. The ability to push HARD onward and then still reverse out of a mess was clutch in keeping things moving along, especially climbing the slight incline at the end...

Can't get enough --- tire chains + wheel speed! I'm pretty proud how my custom big rigs cut thru the snow with their chains on, but idk, this might be a topper. I haven't yet tried the white single cab rig with the new motor setup (gigantic 997 size brushed on 50volts!!! in a built SCX6 trans) so that is still in store for this winter -- que'd and ready to roll, just gotta throw the chains on and get bored enough (or break) the EMO XX. Less wheel speed, but more torque and bigger tires! Who knows.....

One thing I noticed instantly in this vid - - much better lipo power - DUH!! I had the rig inside last night, lipo was ambient temps 70 degrees vs normally keeping them in fireproof safe in garage = COLD!! (and sagged)

 

[WRXronald]

Ok, pinion walked off again! (or backward down the shaft, rather) You know what I mean. ARGH. This time I can clearly see the set screw has come loose.

Dried rinse and repeat, this time used Loctire RED instead of BLUE, and added two little 5mm bore bearings behind the pinion -- preventing it from being able to walk down on the shaft. Lets hope now it doesn't walk off the shaft forward now, lol -- although walking fwd has not been an issue at all it only wants to walk back.

Which brings me to some crow I'll need to eat -- vibes walking that pinion down the motor shaft -- how possible if its a plastic spur gear, right? That's been on my mind for days now. The plastic spur gear can't possibly transfer vibrations like this thru to the pinion and cause it to walk down the shaft the way it is, literally vibing the set screw loose thru loctite.

Well its another DUH moment for me -- and an embarrassing one at that I owe an apology to CROSS RC. The spur gear, IS NOT PLASTIC. Its indeed a steel spur gear. I don't know what caused me to think it was delrin prior --- I hit it with a screwdriver tip and thought it felt like it dug in like plastic, granted lighting wasn't superb and I didn't extract the spur from the transmission at all --- so viewing was a little challenging. Now there is wear on the gear and I can see shiny metal under the black oxide coating ---- so the fact some of the teeth are eaten on the back 2mm of gearing, WOW the FUSION8 was HUNGRY, I mean they are littlerly smoothed off on that small portion. Luckily its got to be close to 10mm wide spur gear (maybe 9) so the 1.5-2mm that got eaten still leaves plenty of metal on metal engagement. I wondered how a plastic spur was holding up to such crazy thrashing I was throwing at it. DUH, nope its metal dumb dumb!!!!

I will also give the RED a full 24 cure cycle, previous I hit it out in the snow after just a few hours -- again, not intelligent.

I'm sorry for doubting you CrossRC!!!!!

 

[WRXronald]

Crew, with chains, and stock tires, today I went down to the river/creek/ravine -- shot three INCREDIBLE vids ---- just slinging MUD, SNOW, WATER, ICE, HILL CLIMBS, catching BIG AIR even once or twice...... confidently can say best vids i've shot of the EMO XX ever.

And unfortunately, then we all went for a plunge, the EMO, me, and the ANDROID lol..... its down for the count for now. Won't turn on and won't charge --- show the moisture symbol.

I'll try to dry it out over the next couple days.... see if I can get the vids off it. Hopeful!!!

 

[WRXronald]

Ok, a 3 vid Snow-Chain series on location at the trail, lol if you can call something from my channel that word "series".... The EMO XX in a nasty little creek basin gets it goin'!!

Two BIG AIR attempts on the way down to the water to start it all out, and plenty of MUDDY SNOW kickin' --- ROOSSTER TAIL style, then eventually a malfunction after some nice action headin to the creek...

Quickly got it fixed but I had to stop recording, so PARTS 2 and 3 will release over the next few days --

Part 2 include Android (and me) in the Drink!? But a few mins of nice river crawlin' beforehand; and Part 3 (yes I got the phone working again for 5 more mins after complete submerge) include a MEGA HILL CLIMB and an EMO XX ICE POOL PLUNGE at the end FTW!

This RIG is FUN (and really capable so far it seems)!!!

Just gotta remove the portal weights (on the rear in this vid) and I think it would have bounced alot less in the rear on landing.

Other than that it launches quite nicely off these soft snowy hill jumps, def the biggest air i've given it so far....

 

[WRXronald]

Next in the series.... abrupt ending with phone in the drink!!

 

[JatoTheRipper]

I can't believe this Cross RC truck is holding up to your abuse! Very nice.

 

[Gula]

Well, things that move and aren't supposed to.......that it's because of vibrations, somewhere. (I suspect it's your spur, now) Take your pinions off and soak in acetone to remove old loc-tite! Same with the set screws. Take the set screws and "machine" a sharp point on the end, and reapply the blue, red if brave! I'd get a new spur gear, and maybe check for input shaft wobble, or you could have a bad bearing on the actual motor!

Phone ok?
How big is the cab of your truck?
This big? I wear a size 12..IIRC
"This" was advertised as 1/5 scale and came with a "STOUT" cnc frame, you could use as a real Ladder! . "Bought an eternity ago" somewhere

 

[WRXronald]

Jato --- this truck is legit i'm convinced. I would recommend, even for the big $. And I'm usually a Debbie downer after a bit of thrashing on toys. Its early yet, give it a full year and a summer first

Gula -- yeah that cab looks pretty close in size i'd say --- sans have a ruler to compare scale. The cab specs -- 13.6 inches front-to-rear, 12.4inches wide not including fenders, 14.6inches fender-to-fender. Tires stick out another 1/2inch from there so just under 16inches overall track width. I would love to have a nice scale ladder!

Last in the series... maybe the best if you ask me, at least the hill climb anyways, the plunge didn't work out so well my front chains got off-whack and held up the tires a bit, that ended things in the water...... Phone shot this whole vid RIGHT after the 100% submerge -- nuts. It was dead before I got back to the car and overnight on the heater vent in the house and it was back up and working next day!!! (no worries either way I keep little of importance on the phone and spares, and its an S10 I think --- OLD and outdated, $200 on the Bay............. I'm hard on phones so no sense in trying to keep a nice one)

 

[WRXronald]

FINALLY, real EMO XX breakage --- lol but it wasn't much!!! And really can't fault CrossRC, I added 1lb weights to the rear wheels (already very heavy duty wheels to begin with) plus 12oz's in chains to each tire.

Completeley sheared the 2.5mm carbon steel drive pins in the rear axles and DESTROYED the anodized alloy 17mm hex hub adapters. They seemed really good quality super beefy hex adpaters too, but then again, destroyed before plastic wheels failed -- testament to the incredible strength of these CrossRC wheels -- the plastic feels IRON hard --- i'm surprised the adapters failed like they did though, with the steel pins driving DEEP into the slots before the pins also failed/sheared.

I was MOBBING thru deep heavy snow and whacked a log hard --- I think it instantly stopped forward motion while the rears kept trying to turn the rig went straight up in the air..... and then slippage thereafter and both rears where sheared and thrashed..... Sheared so bad the PINS were embedded into the adapters and I can't get them out of the one adapter going to need a pick and a file and so what's the point even? Trashed.

From here I think either going to use my mini lathe to machine as set from 4140, or they have a set in 7075 on Ali for $20, that seems like quite a deal I think these ones were just hard anodized but doubtful if they were 7075.

Pics..... got the big F250 single cab out and put the chains on --- charged up the lipos tonight --- going to SNOW THRASH it on 9s tomorrow and see how it compares to what the EMO XX has been doing. The F250 is heavier, longer, wider, bigger tires, but slower --- 15mph vs 23mph topspeed. Its got the 2-speed alloy Vitavon SCX6 transmission though --- so hoping it holds up (the 2.5mm axle shaft pins could be similar failure point again though).

Pretty gnarled --- not really usable any longer...

Comparison of UNIMOG vs F250 both with big chains fair amount of size diff but overall similar scales --

Hopefully vid tomorrow night of F250 snow shreddin'!!

 

[Gula]

Lots of rotating mass.....

 

[WRXronald]

Lots of rotating mass.....

Yeap plus big dual brushless motor torque, fully topped up lipos, if I had to guess i'm sure the pins were already bending somewhat and slowly but surely getting ready to go. Been doni' lots of snow hits and not kind to it, extreme cold today prolly didn't help, sub 10 degrees F.

10 days shipping and $19 all in for four 7075 alum adapters that are +5mm offset as well --- couldn't resist what a deal! Concern with making a set of 4140's is what is next in line to fail if the adapters are too strong will the steel axle output shaft fail instead -- its only 6mm (beefy but not bullet proof). Same thoughts go for wanting to beef up the pins to 3mm. Really gonna need an 8mm portal output shaft to support a 3mm drive pin like in the SCX6 Vitavon axlle kits.

Oh well I'm inclined to take the damaged ones and try to end mill (on the lathe) a new 2.5mm slot across the undamaged section and see if I can rescue them in the meantime.... I mean if its a failure so what, bare minimum its good practice on the lathe. Worst case I grenade (another) 2.5mm end mill bit Suppose I should record that process and show off my new machinist vice setup for the milling attachment while I'm at it..... so cold lately though!

 

[JatoTheRipper]

That's a cheap and easy fix. I'll take that breakage over anything else any day!

 

[ferp420]

the pin shear from what i have seen is caused by loose fitting pins and week pins
my fix has been red locktight double nuts and packing the pin slot with tin foil or aluminum can strips and pressing them together then using drill bit shanks for pins

problem solved

just realized you have the tools just make your own hex adaptors and mechine the pin slit a hair undersized so its a press fit to the pin your using

 

[Gula]

Roll pin....

 

[WRXronald]

Well, I do dhave a few sets of roll pins 2, 2.5 and 3mm bought with intention for axles, I can also make the pins --- I have quite a few 8% Cobalt 2.5mm snapped drills and I always keep them with plans to either flatten and resharpen or cut off the base and use as pins.

Probably I should do something different than the Amazon cheapies I usually fall back to --- I also have some 12.9 grade hex bolts in 2.5mm the long ones have a section of unthreaded straight shank could work nicely -- would be a good strong pin material I think, prone to rust though, might seize up in the axle bore.

The thing is they don't seem to shear too often, I do agree loose fit causes bending and leads to early shear but these were a pretty snug fit - Upon taking a file to the adapter to try and get the broken pin pieces out ---- its indeed soft cheap aluminum underneath the anodization. Its no surprise the carbon steel pins ate into them like plastic now looking closer at the material.

7075 should do the trick, and if not, I will take a stab at making a set out of chromoly --- Either version should result in ONLY pin sheer --- and to Jato's point ---- this is pretty much the easiest, cheapest, repairable failure point in the drivetrain. Heck if you bring a wrench and baggie of pins..... and its not 3 degrees outside ---- its an easy trail job. Also usually leaves the rig able to limp home on 2 or 3 driving wheels w/out repairing.

F250 vid is up on that thread --- not nearly as fun or spectacular to watch as the EMO if you ask me. Still a joy to run, if only it wasn't mostly frozen snow-clay and 3 degrees out there! BRRRRRRRRR!

 

[Gula]

I think you should buy some scx6 internals, treal housings and slap those under a rig...or just some scx6 axles from a take-off. I think you'd be happily surprised by their deft stoutness......especially on these big builds!

 

[WRXronald]

needs to be portals.... never going back (aside from CLOD axles)

I mean, for 6mm portal axle output shafts (on both the Unimog and the F250), and 2-3lb wheels/tire combo w/chains ---- I'd say both the Ryft setup (vitavon'd) and the CrossRC stock stuff has been really solid so far.

I had planned a Vitavon SCX6 axle build up, but alas, $$$ priorities (guess could have had those in place of EMO XX). Some day!!!!