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Old Jul 23, 2015, 10:58 PM
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Question
Correct torque for drive cable collet

Hi Guys,

this is my first r/c gas boat. I am using a collet and round-end 1/4 inch flex drive. I sure don't want the cable to slip out of the tube, taking my brand new prop to the bottom of the lake. Of course, I don't want to over-torque and stretch the threads that hold the collet on, either. How much oomph do you guys put on the wrenches when you tighten the flex drive collet??

Thanks!
Kevin Savage
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Old Jul 24, 2015, 04:36 AM
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Make sure the flex is all the way through the collet, bottomed out is how I go, then use as much oomph as you can and then a little more. Not very scientific I know but you cannot get them too tight.....

You may wish to use a shaft saver as well on the flex in case it does let go. That way you don't loose the cable and prop.
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Old Jul 24, 2015, 05:11 AM
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Here's a nice setup for a round collet using a shaft saver and a grease block, unless you have a T bar with a grease fitting.
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Old Jul 24, 2015, 08:03 AM
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A severe clamping force can be applied to the "true split collets" shown in the photos because they are split from end to end. They can be used indefinitely because they are made of AISI O-1 hardened & tempered tool steel. Notice the hardened thrust washers, in the last photo, that ride between the back end of the split collet & the inside of the clamping nut. All pieces are interchangeable & give a total indicator runout of less than .0002". Severe tightening of the 5/8" hex nut does nothing to the cable or the collet mechanism! The loss of a cable, which could break at any point from the collet to the propeller shaft, is prevented with the simple system shown in the second photo.

Jim Allen
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Old Jul 25, 2015, 10:12 PM
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I don't know of any inch-pounds or foot-pounds of torque, I just tighten them down as much as I can with 6" wrenches.
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Old Jul 26, 2015, 11:18 PM
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Thanks to all who answered my question. I really appreciate the help.
Regards,
Kevin savage
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Old Jul 27, 2015, 03:18 PM
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Quote:
Originally Posted by lvlender View Post
Hi Guys,

this is my first r/c gas boat. I am using a collet and round-end 1/4 inch flex drive. I sure don't want the cable to slip out of the tube, taking my brand new prop to the bottom of the lake. Of course, I don't want to over-torque and stretch the threads that hold the collet on, either. How much oomph do you guys put on the wrenches when you tighten the flex drive collet??

Thanks!
Kevin Savage
Explain to me how a flex cable will slip out of the tube and you loose your prop?
If you have a one piece flex cable with a ferrule welded on where can your prop go? I don't even use a collet.
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Old Jul 27, 2015, 05:25 PM
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Quote:
Originally Posted by txt killer View Post
Explain to me how a flex cable will slip out of the tube and you loose your prop?
If you have a one piece flex cable with a ferrule welded on where can your prop go? I don't even use a collet.
round end cable drives do not have a ferrule welded/soldered on. They rely on the gripping power of a tightened collet to remain in the drive shaft tube.

Square end cable drives do have a ferrule as there is no collet gripping the cable. the cable on square type drives floats freely in the square hole collet. Your cable drive must be the square drive variety.
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Old Jul 27, 2015, 07:49 PM
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Then you should be using a shaft saver(shaft collar) before the strut to hold the prop shaft on from falling off. Just like I use a ferrule. That's what I use on my other boat. I have both types of flex cables (square end and round end). I make my own flex cables now as buying them is expensive (especially the one piece cable with the prop shaft) and switched to using a ferrule on both of my boats.
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Last edited by txt killer; Jul 28, 2015 at 08:45 AM.
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