For most FE boats I would say don't use the teflon liner at all, remove it and get an OSE upgrade cable for your particular boat and use that with no liner. Just grease it well with a thick marine grease and you shouldn't have any problems
Grease the teflon tube
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I run teflon liners in all of my boats, most of which are setup for SAW racing and well north of 50K RPM. I have never had a liner melt as a result of RPM. Alignment and mechanical failure are the chief culprits.Originally posted by photohoward1 View Post6s under load is at least 20v. So more like 40k rpm. That?s a lot for Teflon. It gets twisted up.Vac-U-Tug Jr (13mph)
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I have had others say the same thing. It may be a matter of each particular install. In this case after having a consult with a Navy A&E buddy, he thought the problem was the burr in the drive end as it only burned the back half of the teflon. upon scoping the stinger... scratched all to heck on the outboard bushing... I am ready to test again but will use the factory set up, new stinger, new teflon, new flex,dog,prop.
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I just had a liner melt. greased shaft day before with lucas marine grease and had 3 runs of 2-3 minutes each. 4th run 15 seconds in it melted. 4s with 2280kv motor....30k RPM under load.Originally posted by fweasel View PostI run teflon liners in all of my boats, most of which are setup for SAW racing and well north of 50K RPM. I have never had a liner melt as a result of RPM. Alignment and mechanical failure are the chief culprits.
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- Was the liner actually good-quality Teflon, or cheap nylon? Sometimes it?s hard to tell them apart.I just had a liner melt. greased shaft day before with lucas marine grease and had 3 runs of 2-3 minutes each. 4th run 15 seconds in it melted. 4s with 2280kv motor....30k RPM under load.
- Was there evidence that the liner was spinning inside the stuffing tube? There?s a lot more friction between the liner and the tube than the cable and the liner.
- Was the cable removed and the greased prior to each run?
- Any evidence of cable fraying or swelling?
- How much of a gap between the drive dog and the end of the strut?
- Was a stop watch used to time the runs? It?s sometimes easy to be way off on time estimates.
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1. it was from offshore electrics
2. no
3. no it was greased before the day. greasing after each 2 minute run is ridiculous and speaks volumes about liners
4. no
5. 3/16 gap with TFL stinger that allows gap setting quick and easy
6. yes. a count down timer on the controller is used and started by the trigger to time battery run time. set to 2:30 with 4500mah batteries. time between runs is 2c charge rate/30 minutes.
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I use for flexible shaft Mobil 222 + WD40 50/50%. It won't be a very thick grease. Thick grease gives a strong load on the motor, liquid quickly flows out.
It is important to fix the teflon tube inside the brass one. You need to expand the teflon a little and insert it with force. Or fix the protruding teflon with adhesive tape or heat shrink with glue.
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Melting a Teflon liner is actually pretty rare, so those experiencing issues must be doing something different than most other users. Not all lube is the same, lube meant for full-scale boats may not be the best choice for something it was never designed for. The higher the rpm and the longer the run time the more heat is generated. Cable with a rougher surface will also generate heat. Stuffing tubes not exposed to cooling water will get hotter than those which are exposed. Sharp bends in the tube will increase friction. All of these can contribute to melting the liner.
I haven’t run a Teflon liner in any of my oval or SAW race boats - other than a few stock RTRs - for decades. I run 3/16” cable in 1/4” brass tubing, using 70W synthetic gear oil as a lube. It’s been good to over 40,000 rpm in my record SAW boats and I’ve never worn out a brass stuffing tube even after years of use in the same race boats. This has worked well for me, but I caution others not to just remove the Teflon liner and run the cable in the existing brass stuffing tube. That is really too large in diameter and allows the cable to shorten too much due to windup. The cable should be somewhat smaller than the brass tube ID, but not too much smaller.
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got back from the lake a few hours ago after replacing the teflon setup with 1/4 brass tube. This time I ran 6s for the first time at about 45k RPM. checked flex shaft halfway through the outting and it was smothered in grease and good to go. There's just so much more grease without the liner. What I bet happened to me is I ran low on lube. There's very little of it available with a liner. Im now firmly in the no liner camp.Originally posted by Fluid View PostMelting a Teflon liner is actually pretty rare, so those experiencing issues must be doing something different than most other users. Not all lube is the same, lube meant for full-scale boats may not be the best choice for something it was never designed for. The higher the rpm and the longer the run time the more heat is generated. Cable with a rougher surface will also generate heat. Stuffing tubes not exposed to cooling water will get hotter than those which are exposed. Sharp bends in the tube will increase friction. All of these can contribute to melting the liner.
I haven’t run a Teflon liner in any of my oval or SAW race boats - other than a few stock RTRs - for decades. I run 3/16” cable in 1/4” brass tubing, using 70W synthetic gear oil as a lube. It’s been good to over 40,000 rpm in my record SAW boats and I’ve never worn out a brass stuffing tube even after years of use in the same race boats. This has worked well for me, but I caution others not to just remove the Teflon liner and run the cable in the existing brass stuffing tube. That is really too large in diameter and allows the cable to shorten too much due to windup. The cable should be somewhat smaller than the brass tube ID, but not too much smaller.
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Agreed, liners can be made to work with proper care, but they are really not needed and are a carryover from many years ago before high RPM FE boats were even a thing and a 50-60 MPH boat was considered very fast. There is a reason brass bushings are used in conjunction with steel shafts in many different applications, even high RPM uses like brushed electric motors. It acts like a bearing against steel, and will run for years without wearing out with the proper lubrication
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OoooK! Summary from another newbie. I did RC planes, but that a different problem set. Here?s what I get from the discussion: no liner, flex shaft a close but not tight fit, well greased with a proper marine grease (I got the blue stuff with the pump), stop for a quick check reasonably often. Sounds like a plan.
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