Teflon tubing or not?

[dannyual767]

When I started in rc boating in the late 70's, everyone used teflon tubing with their flex cables. Now it seems like most people don't. I've got to plan the drivelines for both my Dumas SK Daddle and 1/8 scale Miller American.

If I don't use a teflon tube, then what size brass tubing will I use for both 3/16" and 1/4" flex cables?

BTW, my "built in 1979" Dumas Quickie 40 has a short brass tube that ends just after it exits the bottom of the hull. The cable is supported by the teflon tube only to the strut. People look at it and think I'm crazy but that's the way I remember it being done back then :unsure: . It seems to work and the up and down adjusting of the strut and prop are, of course, super easy. If the brass tube goes all the way to the strut, you'll have to do a little bending each time you make a strut adjustment, right?

 

[Chris Attebery]

In short, NO!

Long version: Run brass only. 1/16 larger than the shaft. Run the brass all the way through the strut and use a 1/32" smaller piece of brass as a bearing for the stub shaft. You can flare the end to keep it from crawling up the stuffing tube. Use 90wt Mercury marine gear oil or similar.

No need to bend the brass for each strut change. Let it flex. If it's solid through the strut it won't bind.

Chris

 

[dannyual767]

Okay, I'll move into the 21st century and do away with the teflon tubing. Brass tubing 1/16" larger than my flex shaft and for the bearing,, 1/32" larger than the stub shaft. Does that 90 wt oil stay in that brass tube bearing in the strut? It seems that it would wash out due to the rush of water and the spinning stub shaft.

 

[Ken Hildreth]

Lets see if I can describe this right, you can also put that brass tube in a a short tube that makes it just thru the hull and clamp it in place, this will allow you easy replacement of the stuffing tube if it is damaged. Ken

 

[dannyual767]

Ken, that sounds like a good idea. How do you clamp it, though?

 

[Eric Perez]

You can use CA to glue them together. When you are ready to replace the inner tube, just heat it with a propane torch or soldering iron, the CA will give and you can then procced to replace the inner tube and re-install with a new one.

 

[dannyual767]

Thanks, Eric. I'm learning a lot from this forum!

 

[Preston_Hall]

Ken, that sounds like a good idea. How do you clamp it, though?

You don't need to clamp it and you certainly don't want to glue it. If you glue it in you defeated the purpose of the the thru-hull tube. Also, as you make strut changes the stuffing tube will need to slide in or out of the thru-hull tube.

So what holds the stuffing tube in place? The strut. Before inserting the stuffing tube into the strut apply a little solder to the stuffing tube. Then heat the strut and insert the stuffing tube. The solder won't adhere to the aluminum strut but it will conform to the interior and make it impossible to come out until reheated.

 

[dannyual767]

Preston-more good info for me to file away for my driveline installation! I need to make another trip down to south FL so I can pick up my hardware of choice.

 

[dave roach]

Teflon is"nt a good Choice for a drive line system this will do you more harm then good

my 0o.02 cents

 

[dannyual767]

Yeah, I'm not going to use it. I'm just going to run my flex shaft inside of a brass tube inserted into the larger brass tube exiting the bottom of my boat. I'm moving into the 21st century !

 

[Mike Hughes]

I use a ferrel system for my sport 40. The brass can't go into the strut with a ferrel, so you need to have a clamp. I just use a stainless steel pipe clamp up in the engine well. It clamps down on the the stuffing box. The stuffing tube is one size smaller brass than the stuffing tube. It has no problem keeping it from spinning.

Mike

PS This is a good idea even if your not going to use it. Maybe someone else will.