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LRP X20 shaft play?

LRP X20 shaft play?

Old 09-12-2014, 03:47 AM
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Default LRP X20 shaft play?

I have an X20 4.5T motor. I have noticed that I can pull the shaft out approx. 1.5mm. I cannot push the shaft in.

It runs fine, though, no problem. Rotates fine, no strange sounds.

But is it OK to have this play in the shaft? Does it need to be shimmed?

Just can't understand how a slop/play can develop if it is shimmed properly from factory?
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Old 09-12-2014, 06:11 AM
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The magnets should keep in centered once in motion so you don't need to go nuts regarding shimming out all of the play, you still need some free play to allow it to spin freely during use.

I used to shim my brushed motors down to about 0.2-0.3mm of play back in the day. If you want to try it for yourself, put a pinion on the motor and spin the pinion a few times, the position the rotor ends up is where the magnetic field is strongest and holding the rotor in position. Add/remove shims to keep it in this sweet spot with some end play.

I know some people were deliberately shimming the motor to move the rotor closer to the sensor board to increase torque, personally I'd go for the sweet spot.
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Old 09-12-2014, 12:35 PM
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Originally Posted by Salkin View Post
I have an X20 4.5T motor. I have noticed that I can pull the shaft out approx. 1.5mm. I cannot push the shaft in.

It runs fine, though, no problem. Rotates fine, no strange sounds.

But is it OK to have this play in the shaft? Does it need to be shimmed?

Just can't understand how a slop/play can develop if it is shimmed properly from factory?
no it shouldnt have play,take it apart,i bet the rubber o-ring is missing,i had the same problem,my motor kept cutting out on sharp left turns,the rotor moved away from the hall sensors and the esc would go to blinky mode,it should have 2 plastic shims but different thickness and a rubber o-ring,the thicker shim goes onto the pinion shaft first then the rubber o-ring,the thin plastic shim goes on the hall sensor side,ive just had the same thing with my orca tx so used metal shims to fix that
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Old 09-12-2014, 12:51 PM
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Originally Posted by chasingthepack View Post
no it shouldnt have play,take it apart,i bet the rubber o-ring is missing,i had the same problem,my motor kept cutting out on sharp left turns,the rotor moved away from the hall sensors and the esc would go to blinky mode,it should have 2 plastic shims but different thickness and a rubber o-ring,the thicker shim goes onto the pinion shaft first then the rubber o-ring,the thin plastic shim goes on the hall sensor side,ive just had the same thing with my orca tx so used metal shims to fix that
Thanks, I will take it apart for inspection.

UPDATE: took the motor apart, and sure enough, the rubber O ring was missing. I had a LRP repair kit with the O ring and after fitting it to the shaft with the shim, no more play or slop. Super

Last edited by Salkin; 09-12-2014 at 01:55 PM.
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