Stuffing tube

[CraigP]

Sounds like Schedule 80 stuff... I think OSE's is Schedule 40

[Prodrvr]

My bad...it's .010 wall thickness, 304 stainless.

[CraigP]

I wish I could have got that... I think SS will match the metal properties of the steel flex cable better. Should have less friction between the two and it should hold up better. But I got copper back in there now, and those stuffing tubes ain't easy to change out! Let me know how that worked out for you, if you don't mind.

[Prodrvr]

Here's what I have. I popped the stock brass tube out of my Motley Crew. I bought the K&S 1/4" OD ,028" wall stainless tube. There is really no gap between it and the flex shaft. I ran it twice now, but I wanted some more wiggle room inside the tube. Looked around and found 1/4" OD, .010" wall stainless tube from an ebay seller (Zoro Tools) and bought a length of 6 feet for $10.57 shipped. At the same time, I ordered a shaft bushing from OSE for a Speedmaster strut. The bushing fits the tube perfect. The flex has some play now in the tube. I have a spring bending tool on the way so I can shape it. Now on the K&S tube, the tolerance was so close that I was able to bend it by installing the flex all the way in and then hand bending on the 10" radius wood that I have here. Being the new tube has some play between it and the flex is why I bought the bending tool. What I did see with the K&S stainless compared to the brass is a 2 amp gain in available power. Not much at all, but it was cool nonetheless. Now after I get the new tube installed, I'll take another measurement with the watt meter.

[CraigP]

That makes sense, there is less friction on the SS compared to brass, which has a fairly high stiction value. May not me a big mph gain, but I think it will make the driveline more reliable and be able to turn a higher rpm. I started with the SS before my data logger, so no amp numbers. But I did shoot the temp on some bench run ups, and the SS was lower, by 15 degrees compared to the copper tube. Brass is slightly harder than copper, so I think I'll be re-visiting this stuffing tube. John, any chance you would sell me a foot of the eBay SS? I would like to go back to that. Let me know about that. I guess you need to PM me, they get upset about transactions on general threads. I gotta find me the right Tree to bend the next tube!

[Prodrvr]

Pm sent

[CraigP]

Thanks! Just joking about the tree...

[Panther6834]

I know this is an old thread, and there haven't been any new posts for almost three years, but I'm still hopefully to get a reply...plus, it's three super-quick questions with what I'm hoping will be an equally quick & (fairly) simple answers.

1) Whether straight, or with a slight bend, which material is better to use as a stuffing tube - brass, or stainless steel?
2) Does using a Teflon liner make a difference as to which metal is better as a stuffing tube?
3) Does brass, or Teflon, tubing make a better bushing? This would be a separate, shorter piece of Teflon tubing than the tubing mentioned in question 2. The OD of the Teflon liner & bushing would be the same, but the wall thicknesses would be different (obviously, the "bushing" would have a larger ID, for the prop shaft - 1/8"flex cable, 3/16" prop shaft)

For all 3 questions, assume the exact same IDs & ODs for the stuffing tube, the Teflon liner, and the bushing (with the ID exception mentioned in question 3).


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[klloyd67]

I think brass is better because it's lighter weight, if using teflon either works, I would say if set on using stainless then use teflon for added protection with stainless being so much stronger, I think bushings are a wash, brass probably last longer than teflon assuming properly lubricated....hope this helps

[Panther6834]

I think brass is better because it's lighter weight, if using teflon either works, I would say if set on using stainless then use teflon for added protection with stainless being so much stronger, I think bushings are a wash, brass probably last longer than teflon assuming properly lubricated....hope this helps

I completed the tennis a few weeks ago. On the plus side, although your "advise" came after I finished, you could say I followed it.


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[Grimlock]

"Stiction" is not an issue as long as a good lube is used. Anti-seize is not one of those, it is designed for non-moving parts. Plus 0.005" is far too small a clearance between the cable and the tube. When it is spinning under load the cable winds up somewhat, and restricting that too much will add considerable drag. Whether one "likes" more clearance or not, it works well and has been used on hundreds of boats successfully. Most of my SAW records were set running cable in brass tubing, the fastest with 3/16" cable in 1/4" tube. I have never replaced a stuffing tube due to wear, even on boats which have been raced six heats a month of years.

Lubes which are designed for high speed rotation should be used. There is a plethora of marine greases and automotive oils available - use something which is designed for spinning parts. Hundreds of boaters are not wrong on this, and re-inventing the wheel is not required.


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Im planning to run a similar set up. 1/4" ss tube but the cable I have has a 3/16 prop shaft section with a .150 flex cable (SS inner diam is 4.8mm with the flex cable section at 3.7mm) Is this too much slop?PXL_20210410_011746867.jpg

[Nick1979]

you need .187 flex cable, same as the shaft (3/16, aka .187) Then things should be perfect.

[RMac]

I have a Pro Boat UL-19 with the same problem the tube heating up and melting the mount by the motor. I was going to try a oiler with a tank. Would this work to keep the flex cable and tube cooler? If so what kind of oil do you use? it looks like a gravity feed system and the oil just slowly runs from the tank into the tube? Another question i have is i got an upgraded .187 flex cable that states not to use a teflon liner? Can you run a flex cable without a liner??? Right now im re greasing the cable every 3rd run and possibly going to every other run. Second question, is Lucas Oil Marine grease (like you buy at auto zone) ok to use on these cables or does it have to be the dynamite marine grease. Is there something special about the dynamite marine grease?

[BOATGANG]

First boat, going into my second season with it. I know this is an older thread but it just seemed like the right place for my question. Does anyone glue/secure thier teflon liner in the stuffing tube? Im running the PB BJ24 w/ose cable and strut. @RMac - I run Lucas marine grease in my boat and so far so good .
Thanks