TRX4-XL "SUPERSIZER" -- another BIG RIG to challenge SCX6!!

[WRXronald]

5065 in the house!!! Running it on 6s 5200mah - - 25t pinion with 8mm bore!!!

This is just a quick short walk-around -- can see the SCX6 trans, big axle, and big motor shoe-horned in there --- got to be a 1st for a TRX4 fitting an SCX6 transmission -- or an ONLY -- lol cuz WHY EVEN WOULD A PERSON DO THIS?!

 

[WRXronald]

I'm bored with the 5065 setup --- I don't think its quite going to be fast enough -- and frankly I don't think its going to last long ESC-wise because to get the motor starting up and crawling slowly/smoothly on 6s lipo you have to run it at 22.5 degrees timing and I can just tell the ESC is not happy sometimes --- kicking and glitching a tiny bit.

I've had this problem with the AM32 ESC's since I started using them and trying to go anything over 4s lipo. Even though the Rhino 80A says it can run up to 8s ---- sure maybe for a drone that spins consistently and doesn't deal with stalls, but I don't think in crawlers the high voltage can work out....
So, coming soon, I'm going back to brushed setups -- the brushless stuff is just getting stupid expensive to maintain and replace and idk, seems like everyone is doing it these days.

I was doing brushless Outrunners in crawlers back in 2007. Its old news I get everyone's excited about it in crawlers all of a sudden now that AM32 has gone mainstream in small scale rigs too.

But brushed is the way for this rig --- smoother delivery, etc --- the 5065 was pure power but even in high gear on 6s it struggled a tad to get moving if you really bogged it down, but then when it did get moving it hit SO hard. Not great for a crawler / Basher.

I'm dropping in a 997 Brushed motor --- pretty much the biggest brushed motor in the micro class.

Its a 5285 sized motor can --- stupid big. 6.35mm shaft will have to turn it down to 5mm. 425kv-ish equivalent and the real kicker ----

The 997 is 12s LIPO CAPABLE!!!! Yeah baby --- 50 volts!!! So it should go quite a bit faster than the 5065 brushless 400kv since that can only go 6s max.

The price is right if I can fit the motor mount in the SCX6 transmission mount -- its a bit tricky 5mm vs 4mm and 32mm hole spread vs 30mm. But i'm sure can make something work.

Going to try the motor with a 1080 G2 ESC first (will take a few weeks for the bespoke 12s ESC to get here). The G2 is no longer rated for motors over 550 in its literature but the original 1080 was rated up to 895T motor can size ---- we all know it can run big boys -- it only goes to 3s so a good start point on the 997, not pushing anything hard other than the ESC maybe. If the 997 can push the 33lb rig on 3s lipo with decent crawling/walking speeds around 2.5-3mph ------ then 12s, same gearing, should get me running after it pretty solid!! Good snow Basher is what I need for winters and mud holes.

Thats the other issue with the big brushless --- it still has trouble getting high gear rotating under heavy load, stuck in snow, stuck in mud, etc --- so in deep snow I had to shift to low gear to get the drivetrain rotating again, then sometimes didn't have all the wheelspeed I needed to keep pushing snow like would have in high gear. From a brushed setup --- you just punch it and eventually if its got the torque it will get the wheels spinning slowly but surely and the ramp up is MUCH more friendly and reasonable.... With brushless, if it doesn't go when you pull the trigger and you get that squealing noise --- its awful and you know your killing your magnets when its straining like that, either that or it does go and sometimes it hits way too hard.

idk..... seems weird to be excited to go back to brushed, but for $50 shipped to get motor and ESC that can handle 12s power.... I have a big grin. we'll see. Maybe the ESC won't be very smooth, etc. And $16 for such a gigantic high powered motor --- a brushless version of same would easily be well over $100.

997 - on Amazon!
-- RATTMMOTOR DC Motor CNC 997 Spindle Motor 400W 12-48VDC 0.99N.m 5000-20000RMP Double Ball Bearing, Diameter 52mm for DIY Mini CNC Router Lathes Milling Engraver Polishing Machine

12s ESC - on Ali!
-- 100A 12V-48V 3S-12S Dual-way Brushed ESC High Quality Speed Controller for RC Car Motors


You can also get 6s capable versions of similar ESC for $20 --- and I already put a 775T brushed big block (take up to 6s) in my EMO X4 on 4s lipo (WP880 brushed Esc that the EMO comes with) on the 28t pinion / 60t spur ---- guys ---- it RIPS!!! ITS CRAWLS, it BOGS, Guys ---- it CLIMBS STAIRS!!!! ? WHAA? Shhh don't tell Kevin Talbot.

I"m not even kidding -- I climbed the WOODEN slippery stairs from garage into my house today with it --- with the 2.2 Mud Bashers -- they're so soft and sticky -- was the game changer. And the 775T has so much nice low end power!!! and its FAST too and rips out accelerates solid maybe not quite as ANGRY BIRD as the brushless 4250 but hey -- we all know brushless is the BIG power house! But now I can go to with the motor which could not do with a 600kv 4250 Outrunner. And the 775T I got is about 833kv-ish equivalent so quite a bit faster in rpm alongside the higher voltage capability. $16 for the motor and $13 for the ESC!!! $30!! WOW.

So, the big Q, can a 1080 G2 ESC push a 997T motor on 3s in a 30lb+ rig without melting down? It is only 425ish equivalent - not a lot of rpm.

 

[WRXronald]

I think this might be THE setup to stick with.... we'll see how long the brushed gear holds up. After this run there was zero heat in any of it.. ambient temp. But it's wet and cool today of course.

Power and delivery seems excellent!!!! Doesn't hit as hard in high gear but once it's going its RIPPIN!! I mean the hard-core brushless acceleration out the gates is not there... but the power IS still there and in low gear the is NO want for torque.. if needed I am maxed on pinion 25t... can go as small as 15t so there's alot of room to gear down and MEGA STUMP PULL!!!

This is on 9s lipo / 80c discharge...

Imagine on 12s what it will look like.. might tear itself apart lol!

 

[WRXronald]

Well, I took the truck to Nelson's Ledge's Quarry Park, and well, it just stunk. The ride height was much too high, the rocks were much too wet and slippery, I had the giant and heavy 9s lipo (combo of 6s and 3s lipos in series) in the middle next to the transmission rather than up front for crawling, and I had WAYYY to much air in the front tires ---- I really couldn't crawl over anything much there -- the terrain is NUTS steep.

So in about 15minutes of crawling I ended up on its nose at one point, balanced with tail in the air, and steered it,, ALL the trucks weight on the front steering and on the front four link ------- it TORE the axle apart at the built in steering servo mount / upper 4-link mount. I had thinned that metal under the upper 4-link so larger steel M4 Ball Links could fit in the RBX10 Ryft metal axle mounts --- they were made for very small puny little links. In thinning the metal, I greatly weakened it presumably. It just didn't hold up to 150kg Servo torque + weight and stress of the upper 4 link. It finally gave out.

That left me with an essentially RUINED front RBX10 Ryft metal axle (the printed zinc/steel alloy versions from Ali) the housings are pretty strong on these and I have all Vitavon guts/gears and portals on them --- so I really don't want to get another front axle. Besides at that point may as well go all out and finally get SCX6 axles. But why??

I went to Home Depot and bought a $3.65 piece of quality roofing steel --- super thin stuff but its EXTREMLY strong compared to the 3D pot metal stuff the axles are made of.... I bought 1/8th inch thick too but just not gonna need it. 1/16th piece of "L" channel was PERFECT!!!

I barely had to cut that much off of it to make it fit in there --- I mounted just like it was a 1/10 scale servo --- on the four M3 servo mounts with 12.9 grade carbon steel M3 Allen bolts. Super strong hold. Then re-attached the custom 1/5th scale servo mount to that steel plate and also attach a piece of 1/8th aluminum L channel to make a new upper 4-link mount.

As it turns out -- the whole setup is WAY better than it was before and should not ever break again from what I can see.

I took this time to also completely OVERHAUL the suspension ride geometry and build a new wood flatbed. I used thicker wood this time, junky plywood but its beefy and I ditched the steel plate liner from before --- tis about an inch shorter this time, and weighs same since its thicker heavier wood but no steel liner --- 2.75lbs. Removes with four M8 Phillips studs and can Comp-crawl with no weight on the rear end at all just a half-cab in less than 2minutes -- easy-peasy!!!

Put in a small makeshift firewall aluminum piece to separate the 997 motor end from the lipos and got all 9s lipo UP FRONT all the way -- this really improves crawling performance ALOT.

Let some air out the fronts and lowered the suspension right height 1/2 inch and lowered the body ride height 1/4 inch to get everything sitting lower to the ground and crawling that much better.

Tomorrow I am going to speed test it on 9s with a CELL PHONE GPS and take it Crawling at the river ----- it rips in high gears and goes VERY SLOW in low gear. All on a 997 GIANT brushed motor. It doesn't accelerate that fast out the gate but its almost like a turbo car once that motor is spoolin ---- look out BATMAN!!!!!

Pics of the front steel replacement for bespoke 1/5th scale servo mount and upper 4-link mount on a metal RBX-10 Ryft axle...... and pics of new low ride height stance...... next to an FCX18 custom flatbed rig for comparison on 72mm tires with 1.3wheels.

Also ordered a Cross RC EMO XX Unimog 4x4 ---- giant 1/6th rig ---- finally going to have something completely stock in 1/6th scale to set next to my big rig builds --- so we can see some size comparisons!! They're saying 60 days shipping on the XX ----

See the busted out stock servo mount top portion -- has now been replaced with the steel "L" plate from Home Depot roofing dept....

Next to FCX18 for comparison -- considerably lower ride height updates for both body and chassis as it sits on suspension -- everything is lower to the ground now!!! Almost all droop at the rear, very little up travel left -

Sorry I tired to post individual pics from imgur ... such fun. ... rollseyes

https://imgur.com/a/1DxKFNq

As I said, speed test vids soon -- I expect NO LESS than 12mph on 9s lipo in high gear!!!! (but I tend to be bad at guessing these speeds just sayin)

 

[WRXronald]

Speed test as Promised!!! Golly it sure looks ALOT faster in person ripping oast your face.

I guess it's diff in the moment when you know you're one-hand controlling a loose suspensioned "Leg breaker".