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Unread 08-12-2009, 11:49 AM   #1
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Default electric motor seems to be stuck -

hello all!

probably a dumb question on my part, but i'm out of ideas on how to fix this.

son's 18R was working fine up until yesterday, when it just stopped. steering works fine, wheels turn freely (not locked up), batteries in rx and tx fully charged.

car does not move in either forward or reverse, although you can hear the motor whining like it's trying to turn. cleaned it out (a little dusty) and can't see any rocks or debris in the gears. car's only been run in our garage, so no rocks or anything that could be kicked up into the gears.

all wires appear to be solidly connected, no loose wires/solder.

he has spun out into walls a couple of times, but i think the body flexed and absorbed any damage, i can see no damage on the chassis.

any ideas on what the problem might be? when the throttle is moved in either direction, the motor whines but does not turn. it never runs hot, and was not hot yesterday either. he's run it almost weekly, running the battery back down pretty good with no problems or glitching.

i cleaned and checked as much as i could, and now i'm out of ideas short of ordering another motor in case it got fried somehow (but then wouldn't it smoke or just stop working w/o making any noise like his e-savvy motors)?

thanks in advance!
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Unread 08-12-2009, 12:00 PM   #2
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Brushed motor or brushless motor?
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Unread 08-12-2009, 12:10 PM   #3
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brushed - it's the stock motor that came with the RC18R (stock esc, etc...).

could it be worn brushes?
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Unread 08-12-2009, 12:34 PM   #4
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Might be...especially if it gets used a lot.
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Unread 08-12-2009, 01:26 PM   #5
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well, you could have a rock lodged in the armature or worst case scenario, your brushes are so warn that they are cocked crooked and is wedging against the armature and the bell.
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Unread 08-12-2009, 09:08 PM   #6
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Does the car roll freely without the motor installed?
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Unread 08-12-2009, 09:23 PM   #7
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Quote:
Originally Posted by InspGadgt View Post
Might be...especially if it gets used a lot.
ah, could be - he runs it around the garage at least once/week, usually discharges a full battery pack each time. i think it spends some of that time at full throttle when he's drifting it, so it goes between off-throttle and full throttle repeatedly on each run.

his hands aren't big enough to have much throttle control (has to really reach to get to the throttle) so it's kind of all-or-nothing throttle at this point.
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Unread 08-12-2009, 09:24 PM   #8
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Quote:
Originally Posted by Scubaru View Post
well, you could have a rock lodged in the armature or worst case scenario, your brushes are so warn that they are cocked crooked and is wedging against the armature and the bell.
ah, thanks - i only checked the gears for rocks/debris. didn't look at the motor closely yet. will do that tomorrow.
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Unread 08-12-2009, 09:27 PM   #9
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Quote:
Originally Posted by tru View Post
Does the car roll freely without the motor installed?
not sure - will check on that tomorrow when i pull the motor.

right now the rears will not rotate at all in any direction, it's like the motor is totally frozen.

i didn't see any smoke or smell anything funny like that burnt electrical smell, nor was the motor hot or even very warm to the touch when it froze up.

we've fried enough motors on his e-savvy to recognize the smoke and burnt smell, and we got none of that this time.
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Unread 08-15-2009, 03:17 AM   #10
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take the motor out of the car, and see if it will spin with the ESC power and by hand. Visually inspect the brushes/commutator, as Scubaru said there might be extremely worn brushes causing a problem. If the motor spins when it's connected directly to the battery, then the ESC might be fried. With the motor out, check to see if the transmission is binding. The point of failure should be somewhere along this path...

Even though the RC18 series has an open pinion/spur mating, I haven't had problems with my 18B transmission jamming, even on offroad sessions so I doubt your problem is with the gear mesh.
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Unread 08-15-2009, 07:50 AM   #11
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thanks - will do.

i've not taken one of these apart before so i'm going slowly with the manual and sketching it out as i go (i've got a bad memory - might not remember where everything goes back).

hopefully it's something simple, like a rock in the gears or motor i can just pop out. i've got no idea how to change brushes or do any motor overhauls - i'm sort of resigning myself to the possibility that i may be buying some new and pricey parts to get my son back drifting again (but he does enjoy it).

now his poor crawlers are sitting in my room waiting for him to take them out again b/c all he wants to play with is his drift car...
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Unread 08-15-2009, 07:28 PM   #12
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got it!

thanks for all the help and suggestions - was able to remove the motor and rotate the wheels and gears by hand.

lo and behold, a little twig fell out. must have gotten caught in the gears and sucked around into the gearbox and mashed everything together. when i rotated the wheels, it must have turned the gears enough that the thing fell out.

i was kinda worried i'd be doing the esc/motor upgrade sooner than i planned for.

much mahalo!
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Unread 09-11-2009, 11:02 AM   #13
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kind of a late reply but I'm glad you fixed it, probably not as glad as your son was tho lol.

Looking at Tower the stock motor (?) is only $12 or so, and the motor can is crimped so it's not really easy/feasible to rebuild it. If the stock motor dies, just buy a new one. It's the same with the Tamiya Sport Tuned motor, twice as fast as the stock silver can 540 motor but still under $20. When it's used up, throw it away and buy another one. Rebuildability adds cost to the motor, and if it's not gonna be raced or driven at high speeds, no sense spend the extra money.

I've also heard other RC18 users that put a sort of scratchmade cover over the exposed gearbox (lexan? electric tape?) but I haven't done so myself. It hasn't been enough of a problem for me on the RC18B to bother, even with the body off (the Mamba Micro Pro system is difficult to stuff in and still fit the body). I guess you could block off the bottom of the opening for the motor on the chassis with tape if you're worried about getting more rubbish inside the geartrain.
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Unread 09-11-2009, 12:06 PM   #14
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^^ good point about the gearbox cover- some company makes a popular gearbox cover out of lexan, but you have to take everything out to fit it in there, and it's apparently a really tight fit - some dremel action may be required. i was really thinking about dropping one in there if i had to pull the motor anyway.

it looks like a thin sheet of plastic or aluminum would serve the same function for a fraction of the cost, though.

thanks for the info on the mm pro system - i was looking at that one. i'm not the best at building and fabbing things, so it would probably cause me a fair bit of head-scratching if it wasn't a drop-in installation (i already need to find a small spektrum rx so i can change over to a twin stick 2.4 system for my son - finding room for more stuff is gonna be a challenge).
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Unread 09-12-2009, 02:11 AM   #15
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well it's not that the Mamba system won't fit, I was lazy with cable management, and I refuse to cut/resolder any connectors to make them shorter. I imagine it can fit even with stock length (long) wires. Also keep in mind that the buggy body is extremely close to the chassis on the edges (picture) which is the main part that interferes. The 18R bodies should fit without a problem with my setup. I had to decase my receiver (Airtronics FHSS 3 channel) in order for it to fit on the top of the driveshaft cover with the body on.
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Unread 09-12-2009, 06:19 AM   #16
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ah, cool - thanks.

he has the 18R - there looks to be a ton of space in there. i'm just trying to keep everything as centered as possible over the chassis so in case he hits a wall (which he does) the body will flex, etc... but there should be no chance of anything important actually contacting the wall.
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Unread 09-21-2009, 01:37 PM   #17
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hmm. dunno if i'm going to upgrade the the mm pro just yet.

the stock motor is crazy fast if you turn up the trim a bit (forgot we could do that - had it turned way down for him when we first got it).

my son was drifting around the gym on the oem rubber tires (wore right through the shrink-wrap on the tires in a couple of days). full-throttle, opposite-lock countersteer action and choku-dori drifts around the gym floor.

only thing is when they hook back up, the car just snaps back in the other direction too fast for him to catch it and save it. the shrink-wrap ghetto drift tires were a bit more forgiving.

man, this thing is a blast and a half. he may never go back to his crawlers again... i think i need to get one for myself!
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Unread 09-25-2009, 05:50 PM   #18
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electric tape is a cheap and easy (albiet slightly ghetto) fix for drifting. a roll at our Home Depot is 96c, just cut out four equal-length pieces. I usually make em a foot or so, usually longer so there's more tape for the car to wear through before it hits tire again. If you tape it thick enough, you can just do it around the center of the 18R since the tires (narrow, ie. buggy front and normal) seem to be wider than the etape.

I currently have some parts in the mail for my 18B, my 3s lipo powered MMP 6800 will be able to break 70mph...this is just to see if it can be done though lol, 2s lipo is more than enough for that motor. RC18 series is pocket rocket status
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Unread 09-27-2009, 06:39 PM   #19
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thanks for the electrical tape idea! maybe i can play around with electrical tape or that white surgical tape stuff (varying degrees of "gription").

i tried making thin strips of shrink wrap down the middle of the tire so he has at least some grip when he's turning or at full lock, but the results were so unexpected and unpredictable that i ended up wasting a good bit of shrink wrap (tried wrapping the insides, then tried wrapping the outer edges, etc...).

i even tried wrapping the entire width of the rear tires, and just a strip on the fronts, but that was almost undriveable - any steering input combined with throttle would immediately result in a spinout.

the slightly stickier etape might just make this a little more slick and easy to drift, but not so much like ice skating (shrink wrap).

will give it a shot next week! thanks!
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Unread 12-15-2009, 02:50 PM   #20
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e-tape works much better than the plastic shrink wrap - thanks for the idea!

tried various combinations of e-tape and shrink wrap - shrink wrap on the rears and e-tape in the front makes for an interesting drive - car just snaps around on him really quickly and goes into donuts. really teaches throttle control and steering input, instead of just pegging the throttle and going into long sideways drifts until he crashes into a fence.
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