mxs

Hi guys,

I am sort of starting my electric adventures after running nitro for years.

I am running D5 with freshly cut comm and new 4379 Trinity brushes with I believe (paint is peeling off; I bought the motor barely used) purple springs. I have like three 5 min runs on the comm and the car keeps stalling on me. I come to a full stop and hit the throttle a second later and nothing. The car is standstill until I softly kick it in the rear end it moves. But later in the run even a push wouldn't make it move. GT7 is flashing green so the motor is getting the feed without problems.

I've read about hung brushes and stuff, but I am wondering what's your opinion guys and what's the best way to tackle the problem.

I even pulled the motor out and powered it up to see how it behaves and it was fine for 20 secs and then it starts stalling like it would be hooked up to a drive train.

Any help or tips is highly appreciated.

Thanks a lot to all of you.

fatdoggy

Checklist -

*Did you run-in the motor properly?
*Have you seriously overheated the motor?
*Tear the motor down and check for binding.
*Check the hoods to make sure the brush hood isn't bent and stopping the brush from making full contact to the comm.

If it's none of the above, I'm pretty sure you've got a shorted arm. If it's been like that since you got it used get your money back. I had that happen with a p2k arm once and it acted exactly as you've described. Shorted arm = JUNK

MarkA

iTrader: (21)

It’s most likely a hung brush – what turn D5 motor is it? If it’s 10 turns or less, 3 runs is actually quite a bit on a cut and brushes (welcome to the world of mod racing ).

mxs

It's a 13 turn motor. I am running it most of time on 4 cells only so that's pretty mild compared to 6 cell load.

No the motor never overheated, because I am running pretty conservative pinion.

I don't think it's a shorted arm since the motor was fine for first 5 runs and just after it started show these symptoms. Then I had the com cut and changed the brushes. Got about 5 runs and here we go again.

I do realize that mods require quite a lot maintainance, so I would expect a power dropping the more runs it has in, but I don't think it should stall like that. Also the fact of 4 cells should make it a lot easier on the motor.

mxs

fatdoggy - sorry forgot to reply on a couple of points from your checklist.

motor run-in
I've gone two packs half throttle max. the started to push it more and more. Probably not ideal, but that's the vest I copuld do at that time.

Motor binding
I took it apart and expected all inside but didn't find anything suspicious.

Brush hoods
Inspected them as well, but don't see any problem with them.

Is there any way how to test the arm whether it's shorted?

Thanks again

berger

iTrader: (1)

How many shocky diodes are you using, i had similar symptoms to you when i was just using one diode, added anouther and it was fine. Worth a try

gacjr0

iTrader: (15)

Whenever I get a hung brush, the quick way to clear it is to "pluck" the brush to release the junk in the hood or from between the comm and brush. Just pull on the brush leads gently but not out enough to pull the brush and spring off the motor then let it snap back in. That most likely will get you to the end of the heat or pack, then check what they said. If it doesn't run better after what you described then ?? If you're on carpet also check for wads of carpet getting stuck in there and fouling your comm.

mxs

I am using one 10A shottky diode. I've been snaping the brushes once in a while it seems to help for a bit, but then it comes back.

fatdoggy

If your getting 5 fine runs out before it goes off then it's not shorted. Just a worn out comm/brushes. You can check for a shorted comm using an ohm meter to check the resitance of each pole. Run-in your motor with a 3 cell pack and low timing and you'll get more comm life.

mxs

So in another words what you are saying is that 5 runs is all I will get from this set up? Even if I run 4 cells only?

dontfeelcold

iTrader: (22)

99% chance you have a hung brush, cut the comm and new brushes and your problems should be solved.

Jon Kerr

iTrader: (17)

I agree. I'm happy if I get a second run in on a set of brushes. Granted I run 8 turns most of the time but 5 runs on a set of mod brushes is a lot. Also measure the size of the comm. If it's below .270" after the cut, I'd be weary running P94 brushes. That small of a comm with the wide brushes can wear really quickly.

mxs

Guys, thanks for all the tips and suggestion.

Don't forget that I am running only 4 cells, so that fact and 13T motor means it should last a lot longer than 5 runs. The voltage should make a significant difference in RPMs correct me if I am wrong. I wouldn't mind if the power would start loosing top and lower end after let's say 10 runs. But freshly cut com, new brushes and I am getting only a couple of good runs and then the motor starts stalling. To me that's not normal brush and com wear.

If it is, maybe my electric adventures will be over sooner than they started, because I simply cannot afford to run it.

If these brushes are too hard on the com, what other ones would you recommend and what springs with them. I am looking for rather longer life then high power.

Jon Kerr

iTrader: (17)

What type of car are you putting this in and how are you gearing it?

OleC

Hi MXS,

I've had exactly the same problem with my GT7. The car just slows down after a couple of laps and then just dies.

I have only had it happen with two of my stock motors though. I have switched motors and everything works fine.
I have not detected anything wrong with the motors but after rebuild they act the same. A couple of laps and the cars dies.

It has to be something with the motors cause I've run many different 12T motors on the GT7 later and it works fine.

Sorry I can't help, but at least you are not the only one who've experienced this....