Neil67 Posted April 17, 2014 Share Posted April 17, 2014 New to electric flying. Had a heavy landing with my Wot 4 foame. Prop broke and motor mount dislodged. Fixed motor mount and refitted motor to test it. Ran it without a prop, everything straight and true and motor revved easily and smoothly. Lucky escape I thought. Fitted prop, ran again and low and behold prop pulled drive shaft nearly out of the motor. Odd I thought surely the drive shaft is locked in ,in some way. Gently managed to push drive shaft back into place, then on inspection of rear of motor spotted the tiniest grub screw that appears to hold drive shaft in place. Is that it ? Tightened grub screw, not sure if there is a flat on drive shat, no obvious way to check. Reassembled motor and ran with prop, drive shaft stayed in place. Question am I missing something or is that all that holds the drive shaft in place? Have another new motor, Outlander, and I can see the same grub screw. Quote Link to comment Share on other sites More sharing options...
Depron Daz Posted April 18, 2014 Share Posted April 18, 2014 A lot of motors are made by the same company and they just put the gubbins in different coloured casings. Some motors will have a simple grub screw, sometimes two for balance purposes so check that it isn't the case. Other makes may use a chemical bond which are virtually impossible to break the bond on. Strip your motor down and check that the shaft is absolutely straight by rolling the shaft over a mirror and seeing if any light can be seen between the shaft and the mirror surface. If you can see light then bin the shaft and try and get another. It is impossible to straighten the shaft accurately using a vice etc and only damages the shaft surface anyway. If you use it with a bent shaft, even the tiniest bend, then it can make the prop unbalanced, which in turn can cause the ESC to burn out if too much stress is caused. It will cause shorter flight times also as the unbalanced prop requires more power to turn it. Ideally, the grub screw SHOULD tighten against a small flat area on the shaft. If you cannot see one then carefully measure the spot where the grub screw would sit, and file a tiny flat spot. When you refit the grub screw use a tiny dab of blue Loctite. I also suggest that if you need to replace the motor, go and look on GiantCod or Hobby King for a replacement. If I remember, it is a 920kv motor, and they are half the price of an original replacement, maybe even more! Quote Link to comment Share on other sites More sharing options...
GrahamC Posted April 18, 2014 Share Posted April 18, 2014 Yes... On that motor it is the tight fit of the shaft and the grub screw which hold the shaft in place. If you do bend the shaft, it's possible to buy piano wire which is very fractionally less than 4mm in diameter, cut it to length, grind a flat for the grub screw and use it as a prop shaft. You don't need to worry about the circlip slot or circlip as when the motor is running the case is pulled together anyway. I kept my foamy flying for quite a while like that! If you buy a motor with a bolt on prop adapter, so that the whole motor is fitted in front of the fire wall, and the shaft passes backwards through the fire wall, you will often find that a collet is supplied to fit to the prop shaft so that all of the force is not carried by the circlip. Quote Link to comment Share on other sites More sharing options...
Neil67 Posted April 19, 2014 Author Share Posted April 19, 2014 H Budgie and Graham Many Thanks you for your advice. A real help to somebody new to electric power. Followed your tips and checked and reassembled motor. Test flight resulted in six minute flight, with 35 percent left in 3s 2,200 battery. Seemed ok to me. The advice on a new motor was also very helpful, I ordered a compatible motor at almost half the replacement price of a Ripmax version, and it included the front and rear mountings etc. Have also tested it and all is well. Thanks again for your help. When I listed the post it disappeared almost instantly as other posts arrived very quickly, so very pleased I got a response. cheers. Neil Quote Link to comment Share on other sites More sharing options...
Stevo Posted April 21, 2014 Share Posted April 21, 2014 Best thing you can ever do is replace that stock motor with... something else! The motors are weak... the shaft bends all to easy, and snap on a noseover. Same with the AcroWot foam-e as well. Called BRC hobbies... fitted thier replacement that has a nice fat 5mm shaft!! - took a little fettling though but well worth the effort!!! I think (if I rememeber rightly) I prpped back to an 11x6 - no noticeable drop in performance but I got a few minutes longer airborne. Something else you may want to consider - I used dowel and rubber bands to hold on my U/C - saved the bottom of the fuselage being ripped out on many occaision! Quote Link to comment Share on other sites More sharing options...
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