Cain_dogg03

OK, so I inherited an old rustler, not sure how old, but I'm told it may be 15 yrs. I cleaned it up and dumped some $$$ to get it running as a beater for my 7 yr old. A few runs, and the old stinger 20t engine sputtered and became unresponsive. I replaced with a new stinger 20t, got about 5 - 7 full charge cycles with good run, and suddenly the motor is unresponsive again. There was no smoke, motor shaft turns freely, and resisters on the leads appear to be fastened well. Tested power to the motor at full throttle getting 8.05V. No response with batter connected directly to motor. Some other details:
original ESC (Duratrax Blast Reversing Mosfet Speed Control)
Brand New battery = 6 cell 7.2V High Power NiMH 5000 MAH VenomPower

Beyond that I don't know - totally new to this. Any assistance/insight would be most appreciated - last thing I want to do is buy another motor over and over.

Zonked

My Feedback: (6)

I would check binding in the drivetrain, wheels and double check gear mesh. It sounds like a motor only problem but could you tell how hot the motor was after a run ?

Cain_dogg03

well, the motor heats up a bit, but not as much as I had expected (I could touch it a minute or two after it's last 10 minute run). As for binding, the motor does not run, even when it is free (removed) from the car with voltage applied. Other than that - I have cleaned up the clutch, axels, and rear assebly, but never opened the transmission.

Zonked

My Feedback: (6)

Well the motor is done, sorry i missed that part.

Would check the axles,wheels, transmission and make sure there is no binding that would cause the motor to burn up so quick. I am no brushed motor guru but it should last much longer than 7 runs.

Cain_dogg03

Thanks Zonked. Short of opening the back end, I can say the wheels seem to move freely. I wasn't sure if this is a brushed motor - it is completely encased, with a resister soldered from the canister body to each of the power terminals - does not appear to be serrviceable. Anyone know of any place I might find info on opening/troubleshooting/repairing these motors?

Ttowntoolman

The 20t stinger motor was a throw away motor as I remember.......I also remember that to make these things last a guy had to break them in before using. I thought we used to hook the motor directly to a battery and drop it into a glass of water until the battery went dead. Can't remember the exact proceedure.........used to race a spec class that used this as the only option for motors, a vintage bomber class. Break-in or run-in was very important on this motor for reasons I do not recall. Maybe just because it was sealed and not serviceable.

EXT2Rob

My Feedback: (1)

Egad! If it really is 15 years old, it may have BUSHINGS in the hubs instead of BEARINGS. Check that, and replace with bearings.
Yes, break-in can be important in brushed motors. Even the "throw-aways". You described the procedure well enough. The throw-away motor's brushes can be susceptible to over-heating. I had one just fall off of a fairly new motor. (This was before I got a temp gun)

SOMETHING must be amiss. Even cheap brushed motors should last longer than that. You aren't running the car in grass, are you? 1/10-scale electric RCs don't like grass.

Zonked

My Feedback: (6)

^^^ what these guys said^^^

Last brushed motor I had was trinity P something or another and remember constantly having to tinker with it.

http://www.youtube.com/watch?v=wLwK1nnbNFM

Cain_dogg03

You hit the proverbial nail on the head - hauled it around the grass / concrete area doing jumps off of about 9 stairs (great landings). I did notice that it seamed to struggle on the grass.

Thanks to Zonked again - this time for the video, saved me a search.

I am definitely looking to spend as little as possible, but clearly need a new motor again. If I do this break-in, is it expected to solve the problem? Any suggestions for an affordable alternate motor???

Zonked

My Feedback: (6)

The HPI 15t motor worked pretty good for me in the past but running in grass will shorten its life. Causes lots of drag on the chassis.

Make sure of what your ESC can handle !!

phmaximus

hey even tho u are new to this u did a great job at diagnosing the problem.

generally those motors are throw away, they are hard to get back together... easy to pull apart.

I would pull the backing plate of the motor and check to see it the brushes are still attached and plenty of meat left on them.
if they are i would be thinking the motor was just a lemon, and try another one but this time run it in.
if they are worn out or fallen of then its a chassis drag/gearing issue

only think i can add. it might be worth revising the cars setup if u plan to bash on grass. ie higher ride hight, bigger tyres and lower gearing...

phmaximus

oh one other tip.... dont just nail the throttle from a dead stop.... bring it up a bit slower... like squeezing a trigger

and avoid going from reverse to full forward while its going backwards.... the idea is to reduce the massive arching across the brushes and the communicator, reducing that will slightly reduce heat and increase motor life

Cain_dogg03

Thanks for the tips. I plan to open the motor and see what the insides look like. I have heard rebuilds are usually unsuccessful, but nothing to loose...

phmaximus

That's the spirit.... Hey, if anything u will get a better understanding of how it all works.