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Help with lack of power when bound...

Perkolator

Rock Crawler
Joined
Jul 19, 2011
Messages
842
Location
Placer County
As a newbie to hobby-grade RC I've been very happy with the performance I've been getting with my RTR Honcho. When I first got it, I kept it stock and used it mostly for running trails. Now that I've changed a few things on the truck, I find myself doing more low-speed crawling and have noticed a significant difference in how the drivetrain handles this vs trails - so hoping for some input.

Perkolator's Honcho:

Axial AX-2/AR-2 trans/receiver
Axial AE-2 ESC
Axial 27t motor
stock 87-tooth spur gear w/slipper cranked down tight
14-tooth pinion (current) and stock 21-tooth pinion
Robinson Racing gears/solid output.
MIP drive lines
Over/Under Drive axle R/P gears
Hitec 5645 steering servo
Axial CVDs and aftermarket rear axles
Axial Aluminum C-hubs and steering knuckles
Beef tubes
Tires: 1.9 Baja Claws with LOTS of weight inside, 1.9 Boggers, 1.9 Flat Irons

Ran the rig stock for a couple months and it was great. Then I decided to up the tire size, do a bunch of fab work, and then start crawling more. After all the metal work it was time to get the rig out and test it. I've got a wood pile that I like to crawl in the backyard, and noticed a lack of power or motor binding issue when the wheels get bound up in the crevices between the wood. Not really thinking about it, I just kept going until I saw a slight hint of smoke inside the cab and electronics smell - not good.

Motor was fairly hot, but I thought the problem had more to do with all the metal filings I saw clung to the outside of the motor and also partially clogging the vent holes. All the metal filings were from me not covering over the motor when I was doing all the metal work. I then air-hosed the motor as best I could externally and ran the rig to make sure I didn't fry my motor - seemed ok.

Fast forward to the next time I took it out to some rocks - got the truck bound up again in a crevice and noticed some smoke again and a whiff of electronics. Luckily I was around a couple local RCC guys that day that have MUCH more experience with RC than I do -- we determined the motor was getting stressed too much with the "high gear ratio" of large tires and the 21t pinion, so we swapped it out for a 14t pinion to get the RPMs up into the power band at low speed. This made a HUGE improvement with the low-speed stuff and has helped keep my motor cool with no smoking anymore at the sacrifice of top speed.

Now...I was crawling the rig again on my wood pile and again got the rig into a situation where the tires were kinda bound up and I wasn't getting any power - pretty much like it did before I swapped pinions. Felt the motor and it didn't seem too hot, no burnt electronics smell. Slipper clutch is cranked tight and I'm not hearing the motor spin like I did in the past before tightening the slipper. This is power issue is what I'd like to fix.

I'm looking for input/suggestions on what to start tinkering with next. I was thinking of just swapping the motor for something else because of the earlier issue with metal filings possibly compromising the motor - either another cheap axial 27t or a 35t if it'll help. Perhaps it's just an issue with crawling on loose wood pile that can shift and bind up the tires? Also thinking perhaps I have too much weight in the tires to keep them spinning - is this possible? I am planning to build another rig in the future - should I just throw down now and buy a new motor/esc combo?

Basically I want this rig to keep spinning the tires when I get close to being bound up, instead of crapping out. Everyone else's badass rigs seem to do this and will keep going in a bind or break parts, but mine doesn't. I left the stock plastic spur gear in the drivetrain to keep it as the weak link and strip out before I break other parts. Any help would be greatly appreciated.


Because everyone likes pics:
94e011c0.jpg
 
Yeah, a new motor would be a good idea.

The stock closed can motors that come in the RTR trucks are pretty much garbage, even brand new.

If your going to keep crawling, and high top speed is not what your looking for anymore, but still want it perky, a 35t motor is in your future!

I dont comp, just nothing like that going on in my area,
so I dont bother buying expensive motors. I get my trucks dirty and wet too, so I like to be budget minded with my fun-run only rigs.

I would think about this motor:

Integy Matrix Pro Lathe Motor 35T Single

Its cheap, rebuildable, and can be timed to your driving style.

Im runing about ten of them in my scaler rigs, and never had a problem
with them yet.

If you keep having stall issues even with this, or any other better motor,
then its time for you to wire in an aftermarket BEC, because your
receivers BEC dont have the amps it needs to drive that servo of yours,
and its causing the brown outs your seeing,
or at least the motor stall. Your stock motors brushes are probably shot too.
It dont take long for them to wear out.

Castle Creations BEC 10A Switching Regulator
 
Last edited:
Sweet - Thanks for the suggestions.

Yeah, definitely looking into getting a new motor for it - esp. since I'm gonna need some extra parts come time to build my 2nd rig.

I know the Integy is popular, but I'm strongly contemplating going with a Holmes Hobby motor just for the reputation they have. Most likely a Torquemaster Pro hand-wound - thinking maybe a 35t? From what I'm reading, the HH higher turn motors have more torque and wheel speed than other, lower turn motors. Looks like he's out of stock currently, so maybe I'll just buy something to hold me over while I tinker.

I'll look into the CC BEC. I didn't realize the 5645 was that much of an upgrade when I installed it (got it in combo with my upgraded axles in the classifieds).

"brown out" -- is that the proper terminology for what i'm experienceing?
 
I run the cheap Integys in my submersible SCX and they do alright. Lately their quality seems hit or miss, meaning I've received two different types of Integy motors, one made in China, and one in Japan. The Japanese one has lasted quite a bit longer than the China one.

You can't go wrong with Holmes power. I have a Sportmaster 35 turn in my AX-10 and it has a touch more speed than the 35 turn Integys, slightly smoother startup, and that's their cheap motor. Their good ones are probably night and day compared to the Integys.

Whatever you get, make sure it isn't a sealed endbell like the stock motor because they can't be disassembled, cleaned, and lubed. Even a cheap Integy will outlast the stocker several times over if you keep it maintained.

A "brown out" is where the ESC's internal BEC is overloaded, typically from a strong steering servo that is working hard, and doesn't leave enough power left over to properly operate the receiver or ESC. You'll typically notice it as lack of steering or throttle response until you return the controls to neutral. What your describing sounds like a motor on it's last legs.

Running an external BEC ensures that your steering servo is getting all the power it needs, and prevents brown outs by reducing the load on the ESC's internal BEC.

Really we like topless pics, and those on the rocks. Rarely will workshop pics get you brownie points, so how about you show us your fancy front fender bars and such?
 
For about a year and a half I went through several brushed motors and ESCs. Brushed motors are smooth but do not handle the grit and moisture very well at all. I am running a Momba Max Pro with a sensored Novack 25.5 turn brushless fitted with a 14mm roto and ceramic bearings. I also installed a heatsink but probably was overdoing it with that. It has tons of power geared with an 89t hardened spur and 13t pinion. I could go to a larger pinion with no trouble, currently the motor barely gets luke warm, battery life is off the hook.
http://www.rccrawler.com/forum/2-2-scale-rigs/371177-ttc-build.html
 
Yeah as already said new electric would be the go, I run a Tekin sytem with CCBEC in mine on 3S and it works a treat hey, heaps of power..

Running 3S lipo helped alot with mine as well..
 
"Slipper clutch is cranked tight and I'm not hearing the motor spin like I did in the past before tightening the slipper. This is power issue is what I'd like to fix."

The slipper is there for a reason.............Don't lock it down. If you do and get bound, smoke.............
 
My brother in law just installed a Traxxas 21t 550 emaxx motor in his honcho.. Running on 3S and its a BEAST !!! You can beat it for 1/2 hour and the motor is still cool. He is running a 16t pinion and 87 spur. Its faster than stock 27t on 2s and has GOBS more torque. The motor just explodes with power when you hit the throttle...
I run the same setup in my Wraith..I love it.

The Kids we meet in the Trail, call it the " Horsepower Truck" lol
 
Thanks again for all the input. I'm definitely going to pick up another motor soon. I forgot to mention I'm currently running Dynamite Speedpack silver 2s 5000mAh 20c batteries. I think I'm gonna stay with that since I have several and to swap over to 3s would be an investment I could spend somewhere else. With that said - which HH motor would be recommended for 2s? I thought the 35t handwound would be best, but they're not stocked yet -- should I go with a different turn, something like a 30t? I also have the 2 pinion gears to play with gear ratios if need be, i can also buy some different ones since they're cheap. I'm want a good overall "trail runner" with good torque for crawling and some speed to get up an steep incline or some light mud if need be.

as for the slipper - i cranked that sucker down because it was always slipping when I swapped to larger tires. also because I figure it'd be similar to a slipper removal, which many seem to favor. i figure my drive train is already upgraded fairly well and could handle it, with the plastic spur (and maybe axle pins) being the weak link.
 
Thanks again for all the input. I'm definitely going to pick up another motor soon. I forgot to mention I'm currently running Dynamite Speedpack silver 2s 5000mAh 20c batteries. I think I'm gonna stay with that since I have several and to swap over to 3s would be an investment I could spend somewhere else. With that said - which HH motor would be recommended for 2s? I thought the 35t handwound would be best, but they're not stocked yet -- should I go with a different turn, something like a 30t? I also have the 2 pinion gears to play with gear ratios if need be, i can also buy some different ones since they're cheap. I'm want a good overall "trail runner" with good torque for crawling and some speed to get up an steep incline or some light mud if need be.

as for the slipper - i cranked that sucker down because it was always slipping when I swapped to larger tires. also because I figure it'd be similar to a slipper removal, which many seem to favor. i figure my drive train is already upgraded fairly well and could handle it, with the plastic spur (and maybe axle pins) being the weak link.

Avoid any motor made in China LOL!

Go 3s, sell your 2s, CC BEC, 45T HH crawler motor and 20/87 gearing. "thumbsup" You'll love it, that's what's in my Honcho. Doing the 21T Titan in my Wraith and may do that in Honcho next time.
 
I just installed a new 21t Titan in my honcho 1/2 hour ago.. I put a 22t pinion with 87 spur.. On 2s it's still very torquey.. It will wheelie on my asphalt driveway. In reverse I can stand it on its nose from a dead stop when I punch the throttle. It seems to crawl like a snail and was cold to the touch after 15 mins of running.. I'll have to take it on trail and rock pile to really test the higher gearing on 2s compared to the lower gears on 3s in my wraith.
The titan is rated for 14 volts, so 2s should be a joke for it.


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