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  1. #1
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    Installing a 9/32 tube w/ teflon liner for a .187 flex cable

    Here is the procedure for installing a 9/32 brass tube with teflon liner for a .187 flex cable. First I purchased a new battery tray. Then I found a brass tube with teflon liner from Rocket City Racing that was perfect for this application. Their tube has a step down to .250 on one end so it will fit the stock grommet on the Spartan. I cut the tube the same length as the stock tube leaving the teflon liner stick out a little at the motor end. I then took the battery tray and bolted the the plastic u clamp together. Starting with a 1/4 inch drill bit I drilled out the clamp. I kept the bit straight by centering it in the motor hole. This first bit will remove a small amount of material and keeps the hole alignment perfect. Next use a 17/64 bit to remove the next small amount of material keeping the bit aligned to the motor hole. The final bit is the 9/32 which will remove the final amount of material. The clamp is now the correct size to grip the brass tube. On the other end of the tray you will need to open up the plastic guide. Some slight grinding with a dremmel or a rat tail file and the tube will seat all the way down in the u shaped guide. Bolt the brass tube in and test fit in the boat. Mine fit perfect. After installing put the .187 flex cable in and make sure the rear of the strut is aligned with the brass tube. Your flex cable should be centered in the brass tube and not rubbing on the tube. Whenever you adjust the strut height make sure the flex cable is centered. This was a fairly easy mod and now you can run a .187 flex cable with the teflon liner.







    Last edited by SJS; 02-27-2012 at 05:48 PM.

  2. #2
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    Great post SJS

    Good to know this mod is fairly straight forward and easy to do.

    Also an excellent score sourcing that tubing that steps down to 1/4 inch.

    hog

  3. #3
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    For those who are breaking flex cables I brought this post forward. You can install a .187 cable from Jeff Wohlt and have a great set up.

  4. #4
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    Good job on the postSJS, I have not had any issues with the stock set up yet, but I think I will try your set up on one of my three Spartans.
    "enjoy your ride"

    Dennis

  5. #5
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    Is the tube you bought from Rocket City, this one? -Aeromarine Stuffing Tube with Teflon - .187X18
    Part Number AER-1902-?
    I want to buy it today if it is the right one. Let me know. Thank You.

  6. #6
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    Yes that is the part no. of the one I purchased.

  7. #7
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    (For those who are breaking flex cables I brought this post forward. You can install a .187 cable from Jeff Wohlt and have a great set up. )

    I have my cable .187 now struggling with the coupler he sent me it will not fit right size 5mm to .187 but too long 35mm only got a space of about 40mm on the Spartan. So what coupler do i use.

  8. #8
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    New battery tray - why?
    The ERBE viking will never walk alone

  9. #9
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    What coupler do you use and where from for your .187 flexi.

  10. #10
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    .187 flex shaft from Jeff Wholt (rcraceboat.com), aeromarine 3 piece coupler, and the 9/32 step down aeromarine stuffing tube is all that iis needed. I have a post on this that has all the details.

    erland - you dont need a new battery tray, you can modify the stock one per the post above, that is exactly what I did and its a great setup.

  11. #11
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    Is the .150 the same size as stock so you can reuse stock tube?

    Is .150 enough or do you need .187 on 6s?
    The ERBE viking will never walk alone

  12. #12
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    .150 is same as stock.

    if you run close to stock props, don't run in rough water often, and don't get over aggressive with your driving technique, the .150 will be fine.

    If you start pushing the drive line by running larger props (not recommended on stock electrics), or jumping the boat out of the water a lot running in rough water, or aggressive driving like jamming from forward to reverse, then upgrading to a .187 cable or .078 wire drive is recommended.

    If you are changing out a flex cable due to worn or failure, upgrading at that time is worth consideration.

    You can run the .187 cable in the stock stuffing tube if you remove the teflon liner. This is how I run mine. Keep the cable well greased and it runs fine. If you do eventually wear through the stuffing tube, they are inexpensive, and easy to replace.

    SJS mod is also very good if you prefer.

    hog

  13. #13
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    Quote Originally Posted by Erland View Post
    New battery tray - why?
    The only reason I purchased a new tray is so I have a tray for the stock tube and one for the 9/32 tube. That way I can run either size flex shaft on my boat.

  14. #14
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    I'm new to this so pardon my stupid questions but if you do the upgrade why would you want to "downgrade" later?
    The ERBE viking will never walk alone

  15. #15
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    My guess is, IF something goes wrong. He can have the back up set of gear to fit straight back in?

    Sent from my GT-I9100T using Tapatalk 2

  16. #16
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    I have a pair of Jeff Wolts .150 flex cables that I still run. I actually keep the ..187 for back up and I am not going to use it till the .150 cables fail.

  17. #17
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    I might try the .150 first as well then as this seems to be stronger than stock and durable enough.... I'll get those as a spare waiting for the stock to fail...

    Can you then use the same coupler and do you need a special prop nut? If yes - any recommendations?

    Sorry for all the questions but nothing is more irritating than buying a spare and then lacking key parts - especially when you live in Norway and shipping is two weeks.....
    The ERBE viking will never walk alone

  18. #18
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    Quote Originally Posted by Erland View Post
    I might try the .150 first as well then as this seems to be stronger than stock and durable enough.... I'll get those as a spare waiting for the stock to fail...

    Can you then use the same coupler and do you need a special prop nut? If yes - any recommendations?

    Sorry for all the questions but nothing is more irritating than buying a spare and then lacking key parts - especially when you live in Norway and shipping is two weeks.....
    If I was you, I would order everything for the upgraded .187 setup. I imagine Jeff will get busy this summer with boating season and your wait to have a cable made could be a couple of weeks or more.

    I am really happy with my .187 setup which I completed using this post as a guide. If you go with a .150 cable it will eventually fail again if you run 6s. The stock nimh setup is fine on .150, but anything more is asking for failure in my opinion.

  19. #19
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    I would recommend the aeromarine coupler. You can get an insert that fits the .150 flex shaft and another insert that fits the .187 flex cable. That way you only need one coupler and you simply change inserts to fit the flex shaft you are using. Plus this is a very strong coupler.

  20. #20
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    x2 on the aeromarine coupler recommendation.

    The prop nut on Jeff's shaft have a 10/32 machine thread. The stock shaft is a 4mm nut.

    hog

  21. #21
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    I placed my order from Jeff for the .183 cable on the 4th of June, got an email pretty quick and said it will be a couple of days before it gets send out. got another dispatched email on the 12th.. I don't really care it takes longer anymore, as I live in Australia.
    Not too happy with Rocket City Racing atm. I ordered the stuffing tube and collect on the 6th, only received the order confirmation email, haven't heard from them since. sent a email to them yesterday... hoping they will respond soon.

    Now seeing what the stuffing tube and step down looks like.. it doesn't look too hard to make. just cut a bit of original and glue/solder on the end of bigger tube.
    Last edited by LeoRX; 06-21-2012 at 03:46 AM.

  22. #22
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    Quote Originally Posted by LeoRX View Post
    I

    Now seeing what the stuffing tube and step down looks like.. it doesn't look too hard to make. just cut a bit of original and glue/solder on the end of bigger tube.
    That is correct. You can make your own very easily. Use solder.

  23. #23
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    woohoo! got the cable today.
    Since I've received no response from Rocket City Racing, I've log a dispute through paypal. can't believe it!!!
    It doesn't seem too hard to make, but you will also somehow source the teflon liner. As I have no idea where else to get the stuffing tube or liner. I'm thinking of using the stock tube without liner and build a water cooling system for the tube. nothing fancy, just a bigger tube over stock tube, and seal up both end, mount water in and outlet. this should stop the tube over heat and melt the plastic. Thought it will be something interesting to do, since I've not seeing anyone else build it this way.

  24. #24
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    Forget the middle men, go to the manufacturers. Aeromarine and Kintec have it.

  25. #25
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    Not trying to discourage your experiment with water cooling the stuffing tube, but water cooling won't solve the problem. If you are over heating the tube, twisting up the cable, and melting plastic, the heating problem is caused by friction.

    A properly operating stuffing tube system should run fine without the need for cooling.

    Hog

  26. #26
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    Too true. but, I was thinking of making the cooling with stock tube, therefore no liner. Also, metal weakens and increase wear when heated. Brass do distribute heat quite well. Shouldn't a bit of cool water running around it reduce the heat of friction of metal on metal contact?

  27. #27
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    It is always fun to play around with new ideas, so by all means give it a go if you want to experiment. That is a big part of rc modeling.

    Adding cooling won't reduce the amount of heat caused by friction, it will simply help remove the heat that is created. If two pieces of metal are contacting each other with enough force, and lack of lubrication, excessive friction will occur and create extra heat. So the excess friction is the problem that needs to be corrected, not the removal of the heat.

    Under the right circumstances additional cooling could mask an underlying problem resulting in a failed component. Without cooling, the symptom may be noticed and remedied.

    I have been running one Spartan with the stock size stuffing tube and a .187 cable since mid summer last year. I keep it well lubed (every couple runs) and have had no issues to date. If the stuffing tube does eventually wear through it is simple and inexpensive to replace.

    I have also knotted up a couple .150 cables and heat stressed the stuffing tube and melted the tray. My opinion is that the cable started to fail, which created additional friction and drag, and the situation then compounded on itself until there was a complete, and distasterous failure.

    I encourage you to try the cooling mod, I for one will follow your project with interest, I am just pointing out, that in my opinion, the water cooling will only help keep a properly functioning stuffing tube and flex shaft a bit cooler, but it won't prevent a failure from happening if something is out of sorts and causing excess friction.

    Hog
    Last edited by hog; 06-24-2012 at 09:26 PM.

  28. #28
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    Bump for benefit of member considering this upgrade
    Hog

  29. #29
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    Guys, the Octura coupler is really too big for the set up. the 187 Flex hex is a monster. I also prefer the set screw style anyway. Lighter, balanced better and good grip... but be sure and sold the end of the cable. This makes it last much longer. Sorry if I have been behind on some orders but seems I am the only one making these for the factory fit. I make mine with 5mm SS and then turn the end down to 3/16 with 10/32 threads. Tis make it much better when running Octura props, drive dogs and normal threads we all use.

  30. #30
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    I am bringing this post forward for reference

  31. #31
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    what bout the 3/16 shaft upgrade would that be something as comparable ?

  32. #32
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    I am pretty sure a .187 is considered the same size as a 3/16'' flex shaft...

  33. #33
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    yes that is correct the .197 is the same as the 3/16 cable.i bought jeffs about 3 weeks ago and still haven't seen it yet but i got the aeromarines 3/16 cable and i just measured it and it's .187

  34. #34
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    .187 not .197, I think you have a typo in there...

  35. #35
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    yes you are correct i need to learn to proof read before i hit post i ment .187 is the same as 3/16

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