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Motor making a whining sound

Motor making a whining sound

Old 05-13-2015, 01:19 PM
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Default Motor making a whining sound

Hey sometimes my speed passion motor makes a loud whining sound when I'm trying to do a high speed run. Also when it's making this sound the car goes about half speed even when I'm wide open throttle. Then sometimes it doesn't make this sound and the car goes really fast. If anyone knows why please let me know.
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Old 05-13-2015, 01:35 PM
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Bearings maybe?
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Old 05-13-2015, 01:41 PM
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you sure its coming from the motor. it could be something in the drive train or a bearing,
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Old 05-13-2015, 01:51 PM
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I checked the bearings in the motor and they are smooth. I know that the wheel bearings are a little gritty but I don't think that could make the car go from 70mph to around 35 or 40 when it's doing that whining noise. Also if I hear that noise while the car is going around 40 and I let go of the throttle and get back on it the noise goes away and the car goes to around 70mph.

Last edited by Tc460mph; 05-16-2015 at 01:16 AM.
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Old 05-13-2015, 02:27 PM
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If there's that big of a difference in speed, it's probably coming from vibration from one of the larger bearings.

Just a process of elimination, spin your motor on your car without the pinion gear and see if it makes the noise in various speeds.
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Old 05-13-2015, 11:30 PM
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Well it only happens at full throttle. I don't want to run my motor at full throttle with no load because it will probably shatter the rotor. Also my Rx8 esc is suppose to be sensorless compatible but everytime I take the sensor wires of the motor the motor doesn't move and makes a loud sound. Is that normal?

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Old 05-16-2015, 01:16 AM
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Hey this whining sound only happens if I'm going towards heavy winds but if there is no wind it will only do this some times. So could it be that I have too much load on the motor and the timing is not right?
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Old 05-16-2015, 04:31 AM
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Check that the esc is programed to run both sensored/sensorless. To me it sounds like your running some advanced timing in it and the esc doesn't see the sensors all the time. I'd check the sensor wire too just to see if its cut or loose.
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Old 05-16-2015, 12:31 PM
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I had a problem with the sensor wires breaking but replaced it with a new wire harness. Also I don't have any timing on the motor. I just left it at the lowest setting. I looked to see if I could change from sensorless and sensored but couldn't find it on the hotwire. I think the Rx8 automatically switches the setting depending on if the wires are hooked up or not.
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Old 05-17-2015, 10:06 PM
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Ok today I was playing with my car and it wasn't windy outside. It didn't do the motor whining sound so I'm really thinking that it's too much load on the motor when I am going against the wind. Also does anyone know if too high of a gearing can do that too to the motor?
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Old 05-17-2015, 11:28 PM
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Originally Posted by Tc460mph View Post
Ok today I was playing with my car and it wasn't windy outside. It didn't do the motor whining sound so I'm really thinking that it's too much load on the motor when I am going against the wind. Also does anyone know if too high of a gearing can do that too to the motor?
too hight of gearing shouldn't make the whining sound. did you check gear mesh, belt tension and all bearings?
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Old 05-17-2015, 11:38 PM
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Originally Posted by Tc460mph View Post
Ok today I was playing with my car and it wasn't windy outside. It didn't do the motor whining sound so I'm really thinking that it's too much load on the motor when I am going against the wind. Also does anyone know if too high of a gearing can do that too to the motor?
Most likely you have too much timing for the gearing. Once the motor does not have enough rpm and the timing is set too high, it does not operate properly and starts fighting with itself. Either gear shorter or retard turbo timing.
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Old 05-18-2015, 12:06 AM
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Yeah I'm thinking it has to do with the motor under too much load. I have the timing set to the most retarded I can do and it still does it. My car is only going maybe 70 or 80mph at the most. How do people get the 1/10 scale cars to go over 100mph? Also the speed passion motor is a 7.5t and I'm on a 4s pack.
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Old 05-18-2015, 07:09 AM
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Check if the magnet is still glued to the rotor properly. This motor behaviour you're describing suits that problem.
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Old 05-18-2015, 10:32 AM
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Ok cool I'll try that and see. How do I do that though? Do I just try to spin the magnet buy hand and see if it moves?
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