Drive problem???

[Davy Crockett]

I have another problem with my 425!!

just had a test in the garden and when I give it throttle, it spools up, gets near full headspeed, and seems to hesitate/lose power...

I stopped and tried again slowly and when backing off the throttle, motor keeps spinning, turns the gear attached to the pinion but 1 underneath slows down and no drive to the head/tail. as motor slows down, theres a jerk and drive is re-engaged

I'm confused.com!!!!

[tgwolfwood1981]

Sound like your OWB. Just be glad it didn't happen 20 feet up. I'm guessing you have the original 19t OWB? I got a 20t OWB with a better bearing from rcdumbthumbs.com

[Jerrymac]

It is most likely one of two things. The one way bearing is bad, as mentioned above, or the 'grub' screws in the primary gear are not in the 'indents' on the OW shaft and the gear is spinning on the shaft.

[jason mc]

had that happen last week on my 425, it was the one way bearing (went out in flight, I managed to get it on the greoung safley by some form of luck). got another and its good as new. I hope this isnt a common problem this is going to suck if it becomes one of those never ending things.

[Davy Crockett]

Thanks fellas...

Jerry....checked grub screws, definately OWB

new 20T ordered

[tgwolfwood1981]

Glad you figured it out. From what I have read there are a couple of things you can do to help prevent OWB failures. Use a very slight amount of white lithium grease on our gears every 5-10 flights. Also find a a lubricate (i prefer automotive belt dressing) for your tail belt. Those will help keep the drivetrain rum smooth and run a bit cooler. Another is to gear it so that you aren't running an excessively high headspeed. Heat buildup in the drivetrain can damage the "locking fingers" in the OWB causing the failures. I have mine setup for about 2500 headspeed and I also grease my gears and belt, since I started doing that everything runs smooth as silk and all of my temps have dropped as well. I.e. Motor, esc, and battery. Good luck!

[Jerrymac]

I am not really sure what causes the OWB failures. I have read about quite a few of them on here but I haven't had that problem.
I have been flying my 550 for 3 years and it still has the original OWB, as does my 425 that I have been flying for 2 years now, with a head speed of around 2900 to 3000. I just built my medium boomed, HeadHunter framed '500' this year and it only has a few dozen flights on it, but no OWB failures yet.

Jerry