stuffing tube with or without teflon liner?

[Jeff Wohlt]

I also use bar chain with a few drops of oil... Very slick.

For sport running I can say running teflon is more forgiving for me...even just getting water in the tube still has less resistance and wear compared to brass and metal when "lacking" lube. Also, teflon, generally takes less lube to work well. Again, we also sanded our flex cables a bit to reduce resistance and not be so rough on the teflon. Of course, in the past we did everything to reduce weight and resistance. Those skills just don't seem to be watched as much these days with big cells and plenty of power...but if you do you will have a faster boat...it all helps in one fashion or another.

As far as Bradley...he holds the fastest record in our state so I tend to side with people that put their money where their mouth is....he does.

[DeltaForceMan]

Awesome, thanks

[keithbradley]

Thanks Jeff, I appreciate it!

[don ferrette]

I think you have it backward. There are always exceptions, but when it comes to 100mph+ boats, I think the majority are running Teflon.

I have been attending record trials for years, been over 100mph more times than I care to count and hold or have held over 2 dozen IMPBA records, have yet to see any of the speed demons at any of the record trials I have attended run teflon shaft liners. No offense meant in any way but this is one statement I can't agree with.

[keithbradley]

I have been attending record trials for years, been over 100mph more times than I care to count and hold or have held over 2 dozen IMPBA records, have yet to see any of the speed demons at any of the record trials I have attended run teflon shaft liners. No offense meant in any way but this is one statement I can't agree with.

No offense taken. I believe you. However, I've never seen someone else run over 100mph in an FE boat WITHOUT TEFLON at any of the IMPBA events I have attended...of course that doesn't mean they don't exist, they just don't run at those events. I guess if I travel south or you travel north we could really upset the balance of things.

[RaceMechaniX]

I will try to add my 2 cents here without ruffling feathers.

I have run with and without Teflon in numerous boats including most of my SAW boats. When I consider running Teflon it has a lot to do with the type of cable I will be running and in what installation. Hopefully we can all agree a short shaft mono or cat will have different characteristics than a sport hydro or rigger with a long cable. Other factors come into play such as collet vs. square drive, cable vs. wire, .150 vs .187 vs. .25 size cable. There is no right or wrong answer and if properly done either method can be reliable.

From my own preferences I run Teflon on almost all .150 cable applications whether it is SAW or an oval boat. Partly because I can use 1/4" tube with a liner or if I need to step up to .187" I can remove the liner and run without. Also because the .150 cable I run is very soft and the Teflon seems to dampen it a little better. On .187" and .25" cable I usually do not run Teflon liners. All my heat racing boats whether gas, nitro or FE run without liners. The one exception is one variant of my SAW Q hydro where I do have a Teflon liner. I have three Q saw hydro's, one with .187 cable and a liner, one with .187 cable and no liner and one with a wire drive. I did not see any measurable difference between with or without Teflon on that boat and I was turning plenty of RPM. There was a significant difference going to a wire drive but that is another story.

Teflon does need to be carefully checked and I prefer to only use oil with Teflon and never grease. Grease tends to make the Teflon liner spin even when scuffed and CA'ed in place. When using just a brass stuffing tube the choice between oil and grease is dependent on the application and length of race. My preference is typically grease for heat racing boats and oil for SAW boats.

Some general hints regardless of whether the stuffing tube has Teflon or not. Sanding the cable. I will chuck up the cable in a hand drill and using a 1" belt sander with a fine grit belt and sand the cable down to remove the high points formed by the twisted wires. I will tend take some 600 grit sand paper and some oil and spin the shaft again using the drill till the cable is almost polished. I avoid sanding the ends where the collet or square drive are and the output side whether soldered into a ferrule or onto a stub shaft. I just sand the middle section down. The diameter change is around .015". There is the argument that having the stock rounded wires in the cable has less contact area with the stuffing tube as it should only be a line contact. However in all my testing the sanded cable is always smoother and results in higher speeds.

I prefer single bends over S-bends with the argument that S bends tend to have more change in direction. Sometimes they are unavoidable so just try to increase the bend radius as large as possible.

Cables and collets must be aligned. The same goes for the strut and cable. Having jogs and abrupt angle changes are never helpful for reducing friction.

Run the correct size stuffing tube. Too small and the cable will see lots of friction from the inner wall, too large and the cable will tend to whip. The table below is copied from the OSE shop and I agree with the recommendations for the majority of applications:

Suggested stuffing tube sizes when used "WITH" Teflon tubing:
3/16" brass for Octura .098 Teflon tubing.
7/32" brass for Octura .130 Teflon tubing.
1/4" brass for Octura .150 Teflon tubing.
9/32 brass for Octura .187 Teflon tubing.
11/32 brass for Octura .250 Teflon tubing.

Suggested stuffing tube sizes when used "WITH NO" Teflon tubing:
5/32" brass for .098 Flex Cable.
3/16" brass for .130 Flex Cable.
7/32" brass for .150 Flex Cable.
1/4" brass for .187 Flex Cable.
5/16" brass for .250 Flex Cable

Here are some of my notable set-ups:
T-Hydro SAW: 3/16" flex cable with squared end on motor side and conventional 3/16" stub shaft and ferrule. Brass stuffing tube only.
S-Hydro SAW: 3/16" flex cable with welded stub shaft and collet on the motor side. Brass stuffing tube only.
Q-Hydro SAW: 2mm wire drive with thick Teflon liner and bonded 3/16" stub shaft. Brass stuffing tube with thick cross section Teflon. i.e. the wire had little clearance to the inner wall.
N2 and P mono SAW: 2mm wire drive with short brass stuffing tube and Teflon liner plus 3/16" stub shaft. Flooded well design.
N2 heat race mono: .150 cable with Teflon liner and bonded stub shaft.
P heat race mono: .187 cable directly in brass and welded stub shaft.
Q mono heat race: 3mm wire drive with flooded well. 1/4" Brass stuffing tube goes into strut. Short Teflon piece with tight diameter seals flooded well near the motor side.
P-Ltd Rigger: .150 cable with Teflon liner and bonded stub.
P-Ltd and P sport hydro: .150 cable with Teflon liner and bonded stub.
Q/T heat race rigger: .187 cable with squared motor end running directly in brass tubing.
T Offshore and Open cat: 1/4" cable with welded end running directly in brass tubing.
S/T mono SAW; 1/4" coarse wire cable with squared motor end running directly in brass tubing.

All my nitro and gas boats run without Teflon whether for heat racing or SAW.

There is no silver bullet to answer the debate. It's preference and set-up to make it work.

TG

[flraptor07]

Thank You Tyler, Awsome info!

[Jeff Wohlt]

Agreed....NO teflon with 187 cables.... Just too rough of a cable. This discussion is about as crazy as wire vs cables. A good discussion is always welcome and to see other racers options and opinions.

[kfxguy]

Agreed....NO teflon with 187 cables.... Just too rough of a cable. This discussion is about as crazy as wire vs cables. A good discussion is always welcome and to see other racers options and opinions.

too rough even if sanded and polished?

[keithbradley]

Good stuff as always Tyler.

Another thing that's important is the end of the flex. I round and smooth the ends of all my flexes, so when inserted there's not a sharp edge to catch and scuff up the Teflon. Of course this is obvious to many but important nonetheless.

I run thicker liners with 8mm tubing for .187" flexes and 10mm tubing for .250" flexes. While the thin liners used with 9/32" tubing have been known to get soft and wad up, I have never seen the thick liners do that. There is also a significant difference between the two when it comes to spinning inside the tube. I have run all types of flex cables and used (a reasonable amount of) marine grease with quality liners and never have a problem, even without scuffing and/or gluing the liner. However, I can't say the same for the thin stuff. If I only had the options of running either the cheap liner or nothing, I would probably run nothing.

[keithbradley]

Agreed....NO teflon with 187 cables.... Just too rough of a cable. This discussion is about as crazy as wire vs cables. A good discussion is always welcome and to see other racers options and opinions.

I run Teflon with ALL of my .187" cables Jeff. I've ran some with 1/4" brass/no liner as well but had noticeably better results using 8mm tubing/Teflon.

[Jeff Wohlt]

No...you could sand it and polish and it would be fine.

[Shooter]

Keith, what ID Teflon do you use with .187 cable?? Reason I ask is that I've run into two ID's that are very close. One is slightly smaller and creates a very tight clearance making it more susceptible to 'wad up'. I think this may have actually started the 'bad reputation' that Teflon liners have gotten around here.

[keithbradley]

Keith, what ID Teflon do you use with .187 cable?? Reason I ask is that I've run into two ID's that are very close. One is slightly smaller and creates a very tight clearance making it more susceptible to 'wad up'. I think this may have actually started the 'bad reputation' that Teflon liners have gotten around here.

5.5mm ID., so roughly .216".

Here's a comparison of the Teflon I use with .187" flexes vs. the stuff I typically see used (or sworn off). It's a pretty considerable difference.

[Shooter]

Thanks Keith. 0.21". That is EXACTLY what I am measuring on the 'good ones' that I have. The BAD ones that I received are measuring 0.19"!!! Way too tight.