Just would like to know what you guys think, happend to this shaft .
15497796908661491639874473153148.jpg
15497798591884438401098957338604.jpg
Screenshot_20190210-192131_Gallery.jpg
Just would like to know what you guys think, happend to this shaft .
15497796908661491639874473153148.jpg
15497798591884438401098957338604.jpg
Screenshot_20190210-192131_Gallery.jpg
Last edited by Speedfreek; 02-10-2019 at 03:53 AM.
My guess is you ran an out of balance prop and/or prop nut and a crack propagated from the bottom left in picture 3 which allowed the shaft to bend and threw it further out of balance and quickly snapped the end off.
Why are the step downs in shaft diameter there? Deleting them would make for a stronger shaft, or if they have to be there putting a raduis on there inside edges would spread out the stress load a little and make it a bit less failure prone.
Paul Upton-Taylor, Greased Weasel Racing.
What is the diameter of the step down & prop size on that shaft ? is it a 3/16" bore prop. As you are running very large powerfull TP 5850 motors on 12s, also as said a step down with no radius will also break easier. It also looked like there was not enough gap between the drive dog & the stinger to allow for flex wind up.
Yea 3/16 , I have gone up to the next size now and I machined it so I can have more of a gap too.IMG-20190210-WA0007.jpg
to me looks like of scarring on that shaft (maybe more grease or more frequent greasing)
although after thinking about it, it would effect the flex shaft not where it broke, but still in all looks like it should have some grease in there
That is from the bearing. BTW Speedfreak I run two bearings at each end to carry the load and last longer. Once they wear they could cause a wobble and that may happen quickly with only one bearing. Something I’ve been doing on the step down shafts is run a 1/4” drive dog which locks the prop. Just a theory but I haven’t had a stepdown shaft fail.
So how much would you say a 1/4 drive flex approx 8 in long would contract on eceleration ?
whats it out of probably not balanced prop could be a bad bearing too
I think I did the same thing on my 10s mono, 1/4” shaft stepped for 3/16” props, I had a 3/16” drive dog and that’s where it snapped. I’ve gone to a 1/4” dog now.
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Namba District 16
1/8 Miss U.S., 1/8 59 Maverick, 1/8 Executone, 1/8 Smokin Joe, 1/8 Bud, MLGSX380, AC Pro40II Q Sport, AC Pro40II nitro,Twincraft mono 10s, Vision AOPC, VS1 FE, M34.
The ones that I ordered have graphite dots in it to lube the shaft .s-l400.jpg
Last edited by Speedfreek; 02-18-2019 at 04:26 PM.
Way to go for now.
Going to centre drill on the lathe and press the prop shaft in that way it has no week point.....20190212_145641.jpg
Last edited by Speedfreek; 02-18-2019 at 02:39 AM.
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