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Old 01-16-2011, 09:21 AM   #1
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Default LNC motor, esc, or gear problem

Hey all, I've got an issue with a new to me but used Losi Night Crawler. I bought it as a BND with a titan 550 21T installed. The previous owner noted that he was having some trouble with that motor combo, but figured it was just the motor and not anything else.
This is what it does; It runs fine, forward and reverse, but only IF you ease on the throttle.. if you punch the throttle, it just stalls. The esc lights go to the "fail" mode, for lack of a better term (all three LEDs light, just like it would when you're transitioning from forward to reverse), but if you let off and just ease on the throttle it works. The same might happen midway through an obstacle. Does this sound like a motor issue (dirty brushes?), something with the esc? or possibly the worm gears locking up and not letting the motor spin? I don't think it's the last, because the motor doesn't seem to be fighting any resistance when it won't spin (no hum, etc), it just doesn't turn, but then will go if you ease on the throttle.

I should also add that this isn't a newbie-to-RC question. I've been around for a while, and own 13 cars, so it's not my battery, or my radio. Also, don't respond with "you should have bought an Axial", or some other silly pointless answer. I'm really just asking those that are familiar with the car or have some real insight. Thanks!
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Old 01-16-2011, 02:24 PM   #2
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What esc is installed? If it is a factory losi, check to see if it is in lipo or nimh mode in the programming. Red is lipo, green is nimh. I have had 2 LNC's and have never had trouble with a motor or speed control. I run a 35t handwound on it on a 3S and it has plenty of wheel speed and torque.

I hope this helps.
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Last edited by handicrawler; 01-16-2011 at 02:36 PM.
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Old 01-16-2011, 07:13 PM   #3
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You should have bought an axial.

Seriously though, tell use the ESC you're using, if it a Castle Sidewinder and its got three lights, its out of range of operation, or the setup has failed.
You would either need to recalibrate or reprogram.

As an aside, aren't the Losi's intended to have a brushless motor to overcome the drag of the worm geared diffs?
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Old 01-16-2011, 08:46 PM   #4
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Quote:
Originally Posted by handicrawler View Post
What esc is installed? If it is a factory losi, check to see if it is in lipo or nimh mode in the programming. Red is lipo, green is nimh. I have had 2 LNC's and have never had trouble with a motor or speed control. I run a 35t handwound on it on a 3S and it has plenty of wheel speed and torque.

I hope this helps.
It's the stock esc that comes in the BND version. I did some experiments tonight, and pulled the 550. First I tried the esc with the motor disconnected just to see if under no load at all the problem would happen. I'd be able to tell by the LEDs on the esc. It worked fine. So then I plugged in the stock motor held in my hand. It worked fine in both forward and reverse. Then I plugged in the titan held in my hand. Lots of issues, just like it would act in the crawler, except there was no load on the motor at all. Then just to try it, I plugged in a speed gems with a fairly strong magnet.. It couldn't even turn it over.. it just hummed.
So I installed the stock motor in the crawler and drove it around. It works, but I can still get it to "sometimes" lockup/stall if I punch it in reverse, and forward, although less often. It makes me think the esc has some issue with running a stronger motor. I don't know if these crawler escs work differently than a regular esc, so maybe they're not supposed to be able to turn a higher turn strong magnet motor? For some reason I doubt that. I'm really hoping someone can shed some light on this. I bought the BND version (used) so I could just play around with it and not have to buy a esc/motor combo for a roller. I'd hate to think I have to replace this esc when I thought I was buying a functioning setup.
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Old 01-16-2011, 08:51 PM   #5
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Something else to consider might be if the axles have been greased lately. Losi crawlers use a worm/spool combo in the axles and they have to be greased and maintained often or they will either drag or strip from heat and friction. Someone correct me if I'm wrong, but I think every 10 packs or so they should be checked.
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Old 01-17-2011, 02:15 PM   #6
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Originally Posted by handicrawler View Post
Something else to consider might be if the axles have been greased lately. Losi crawlers use a worm/spool combo in the axles and they have to be greased and maintained often or they will either drag or strip from heat and friction. Someone correct me if I'm wrong, but I think every 10 packs or so they should be checked.
I thought of that too, but they spin freely and the motor had the issue even when not connected to the tranny. I spent some time reading through the manual online (didn't get one with this used rig) and remembered seeing something while testing it earlier that didn't make sense. I would have to stop, THEN go into reverse just like a regular ESC, not like a regular crawler would with no pause between F and R. The led would blink red twice on startup, then go to solid green. Solid green is forward/reverse mode, but there is a "crawler" mode (red and green LED simultaneously lit) that has no pause between forward and reverse. It also applies the brake as soon as you let off just like a power tool. So once I set it to crawler it worked fine. Just a few minutes ago I disconnected the stock motor, and plugged in the titan to see if that was ok too. It works.
If you go back and forth quickly a lot the comm on the titan gets some carbon on it from arcing, which makes it stutters a little, but it clears up. That seems to have fixed it. I even tried it on all three other esc settings and it didn't like any of those except "crawler".

so now that it's working it's a lot of fun. I'll try out the titan in it tonight with the esc setting in the right mode. Then I'll probably tear out all the electronics and mount them the way I'd like to, and probably take the axles off to see what condition they're in. I read a thread where a guy had drilled an access port in the axle housing so he could spray grease in, and installed a plug. That sounds like a good idea.
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