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  1. #1
    RC Qualifier
    Join Date
    Apr 2012
    Location
    Charleston SC
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    364

    Flex shaft to use with x447 prop

    I decided to give the x447 prop a try on my stock electronic spartan a few weeks ago. It runs like a champ and blows all of my other props out of the water. But after about the 5th time out I noticed what seemed to be a LVC at full throttle. It turned out to be the flex shaft spinning inside of the coupler as eventually it let loose. I have an aluminum motor cooling jacket, I have opened up the single water inlet (on rudder), added an additional cap on the ESC, and changed the connectors out to the EC5's. I also have only ran this prop on Thunder Power 65c/130c 5000mah 6s lipo's (dual 3s). I have zero problems with heat.

    I never got around to asking, but if I had issues with the Jeff Wohlt .150 flex shaft slipping in the Aquamarine 3 pc coupler with the x447 prop wouldn't have that been an issue even if I had a different motor/ESC? Or should I be running the .187" flex shaft with this prop?

    I'm also thinking due to the length of my run that I jammed into full throttle a bit too soon in which the prop just had a bit too much drag which led to the flex shaft slipping.
    E Revo brushless, XO-1, Nitro 4 tec 3.3, HPI RS4

  2. #2
    RC Qualifier
    Join Date
    Jun 2011
    Posts
    375
    I ran both boats all summer with the wholts .150 cable and aeromarine couplers with no problems.We ran various props all summer including the prather ss220 and many Octura props up to the x448. We had hundreds of runs on the boats without any problems. My son and I also love to do hole shots and this never hurt the set-up. If your aeromarine coupler started slipping I would suggest a new insert and cable.

  3. #3
    RC Qualifier
    Join Date
    Apr 2012
    Location
    Charleston SC
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    364
    Thanks for the feedback. I think I may have not had the coupler tightened enough. I was using a 15mm wrench to snug everything and I have been noticing it was slipping a bit. That's just me being too lazy to walk into the garage and get the correct size wrench.

    Luckily I ordered several inserts with my original order. I replaced the cable and insert a few weeks ago and haven't had any problems since.
    E Revo brushless, XO-1, Nitro 4 tec 3.3, HPI RS4

  4. #4
    RC Qualifier
    Join Date
    Jun 2011
    Posts
    962
    I was surprised to read your cable slipped in an aeromarine coupler.

    I would suggest that a .187 cable might be worthwhile considering with that prop. Not because of slipping in the coupler, but because that is a pretty large prop and is likely putting a considerable amount of stress on the .150 cable.

    I know SJS has run without problems on the .150, but my experience was different, I twisted up a couple of Jeff's .150's and a couple OEM .150's.

    Driving habits, water conditions, etc etc all factor in, so individual experience will differ.

    hog

  5. #5
    RC Enthusiast
    Join Date
    Nov 2012
    Location
    Sydney
    Posts
    22
    Hi Guys,

    I'm just in the process of upgrading shaft to a thicker one. We have a guy here in Sydney who makes them. He says I should get rid of the sleeve in the copper tubing. He recommends putting the stock copper tubing inside a slightly thicker one and pack them with grease when I put the shaft and prop back in.
    His justification for the two copper tubes is that the stock one is very thin.

    Anyone heard about this before I go ahead and do it? Or should I be the Guinea pig?

  6. #6
    RC Champion
    Join Date
    Aug 2011
    Location
    El Cajon Ca
    Posts
    1,804
    Has this guy actually done what he recommends and specifically to a Spartan?
    "enjoy your ride"

    Dennis

  7. #7
    RC Qualifier
    Join Date
    Feb 2012
    Location
    Montreal, Canada
    Posts
    547
    I still have my original brass tube, I don't see anything wrong with it, you should try that if you want, but you have to deal on bending the tube after. My 9/32 had the same thickness.
    Here are the images to compare

    Bend area compared with the straight flex cable.

    I seen on my old tubing there was a binding on the discoloured part, just that no issues at all.
    Sharing is the best thing to do on EARTH legally.

  8. #8
    RC Enthusiast
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    Nov 2012
    Location
    Sydney
    Posts
    22
    Quote Originally Posted by orca44 View Post
    Has this guy actually done what he recommends and specifically to a Spartan?
    Dennis,
    Yep. Apparently he builds for other people and has for his own high rpm nitro boats.
    I think I'm going to give it a go. Just after Christmas I'll do a post on it.
    I'm waiting on my parts to arrive from Offshore Electrics, I'll play and tune them first.

  9. #9
    RC poster
    Join Date
    Jan 2013
    Posts
    2
    Go to offshore electrical .com they make a nice upgrade .150 I run on my sparten killer

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