Granite Strange grinding then spur just gets shredded

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Hecktangle

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Arrma RC's
  1. 4x4-Mega
Hi, having some problems with my Granite Mega, that I can't seem to work out. So, I fitted some rubber shielded bearings, I've not done the diffs yet because well, I'd like to sort this first mostly. The spur and pinion have been making clicking sounds, so I looked at both, and the pinion was coming loose. After multiple tightening attempts, all unsuccessful, I used some threadlock on it and tested it, and it made a grinding sound, followed by a louder grinding sound, followed it turning out it ate a chunk of the teeth on the spur. Pinions still nicely in place, so, small victories I guess. But, I can't work out why the grinding would have occurred, and I was wondering if anyone has any ideas to the cause or the solution please? Spur gears are cheap, unless it decides to remove more teeth from them
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Do you have the full width of the teeth of the pinion lined up with the width of the spur gear? In those pictures, it looks like they are offset, or maybe the pinion slid down the shaft of the motor.

Are you tightening the set screw onto the flat spot of the motor shaft? Also let the loctite dry overnight before use. Good idea to spray it with a little motor spray first to make sure all the oil is off the set screw.

Not too many other ideas, but turn the spur by hand and make sure it has the right mesh all the way around.
 
Do you have the full width of the teeth of the pinion lined up with the width of the spur gear? In those pictures, it looks like they are offset, or maybe the pinion slid down the shaft of the motor.

Are you tightening the set screw onto the flat spot of the motor shaft? Also let the loctite dry overnight before use. Good idea to spray it with a little motor spray first to make sure all the oil is off the set screw.

Not too many other ideas, but turn the spur by hand and make sure it has the right mesh all the way around.
Yeah, set screw was on the flat and it was on the full width. However, I have noticed the shaft of the motor can move up and down a tiny amount, could that be the cause? Thanks
 
Yeah, I've got new ones ordered, the issue is though, if I can't work out why this one got chewed so fast, I'm gonna be replacing them incredibly quickly.
A loose pinion will do it. A loose motor mount will do it. Debris in the power module will do it. Only you can tell us for sure.
 
Blown bearings could do it too. Take off the spur and run the motor and make sure the pinion runs circular with no wobble. Take off the pinion and spin the spur and make sure it spins with no wobble and bearings aren't blown on either.
Yeah, set screw was on the flat and it was on the full width. However, I have noticed the shaft of the motor can move up and down a tiny amount, could that be the cause? Thanks

Pretty much all motors have that, just make sure the pinion is lined up around the "middle" of that play.
 
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My spur gear stripped when I blew the motor bearing closest to the pinion gear. The motor actually ran somewhat okay but there was a little play.
 
If that's the stock pinion then you have it installed bottom side up and usually it's flipped around (the 14T marking facing the bottom of the motor). In your pic it looks like only one part of the teeth from the spur are matched with the teeth of the pinion and the other half of the spur teeth are rubbing on the rounded/non teeth part of the pinion.
 
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