Speedmaster Sport 20 hydro strut

[Old School]

You have no adjustment with the brass entering the strut. If you want to be able to adjust your strut, and I think most of you do, then you can't have the brass going through the strut. .......Mark

I would have thought that the flex over the exposed length of the stuffing tube would allow the degree or two of adjustment needed. The stuffing tube is held captive where it passes through the hull giving a few inches of exposed stuffing tubing before entering the strut tube. On my hull I think that about six or seven inches of tube will be exposed. Would not the flex in the brass tubing be sufficient for any needed adjustment? One cat hull my son had the stuffing tube was bonded internally with several layers of glasscloth, however where it passed through the hull the sealing was done with a rubber mastic material. This gave quite a bit of flex but also sealed the hull.

[rol243]

You don,t want any flex where the stuffing tube exits the hull as any adjustments done on the strut end will put the opposite end slightly out of motor collet alignment.

[Old School]

A stinger requires "pivot" adjustment but with a strut the movement I assume is vertical (either up or down). The stuffing tubing is held rigidly where it passes through the hull so any flex/adjustment is impacted between the hull through fitting and the strut mount. If the stuffing tube is flexibly mounted through the hull then, yes, any flex at the strut will have an impact on motor/flexshaft alignment.

[785boats]

The strut requires adjustment for both up & down, and positive & negative angle in a hydro.
The small nib of tubing into the front of the strut (about 3/16") still allows the negative & positive adjustment as well as holding the end of the stuffing tube firmly at the strut. So when the strut is moved up & down the stuffing tube moves with it. In my experience, if the stuffing tube stops short of the strut, the teflon & flex cable develop a slight s bend when you raise or lower the strut ,unless you rebend the stuffing tube a bit more.

I wouldn't trust a free floating stuffing tube in one of my 1/8 hydros with a 1/4" flex cable.

Each to their own I guess.

[bob horowitz]

I see some people using a larger diameter tube epoxied inside the hull so you can move the stuffing tube. It seems to be called a flooded stuffing tube. You might be able to find it if you do a search. I don't remember who had a thread about it.
Bob

[CraigP]

For clarification, I run the setup mentioned where there is about 1/4” of stuffing tube penetration to the strut. I open this diameter up on the end of the strut, and use silicone sealant to take up the gap, giving me a stress free joint on the stuffing tube so as not to disturb the motor alignment. This joint is then covered with more silicone on the outside of the stuffing tube and strut, then finally covered with heat shrink tubing. I also never use the floating bushing. I use leaded Teflon bushings (3), pressed into place, and the back of the strut is sealed with a precision lip seal. This is tooling I perform here at home. I have no water contact with the grease and flex shaft at any time, it is sealed under the hull. The motor side of the stuffing tube I reduce with a short piece of 7/32” tubing to provide a somewhat better support for the flex shaft, running to the motor coupler.

Also, my adjustments are in the 1/8” range on the strut up and down. I have strut depth targets that I build the boat to...

Many may not realize, but the twist of the flex creates a scroll pumping action on the grease, moving grease to the strut. The only grease that would leak from the front of the stuffing tube is overfill and also grease expansion as heat is generated when the boat is running. Once this balance is achieved, I don’t mess with flex lubricants for about 20-25 runs.

[Old School]

Many thanks. This has turned into a very informative thread.

[MarkF]

Some of the gas guys are using the floating tube because they can and don't care about water get into the boat. It allows them to change the stuffing tube should it ever get damaged.
785 yes you have to bend the brass a little when you make changes but once you have your set up, your done. Technically your strut should stay straight but I know how we need a little angle to get our boat to run right sometimes.
Craig I would never drill my strut out bigger just so I can run the brass into it and then add silicone for adjustment. That's what we call Jerry rig. I can never get more than 4 runs before my grease is gone but it also depends on how fast your boat is and how long your cable is. The grease slowly goes out the back end and it doesn't matter how well your sealed up everywhere else. Good for you though if your getting over 20 runs. I still grease all my cables at the end of a days run just to make sure the water is out and my cable is greased till the next run. You never know if a cable is bad because they rust from the inside out. Then people wonder why there cable snapped and there prop is at the bottom of the lake. Always good to grease your shafts at the end of the day when you run. Sorry Craig this isn't all aimed at you. I know your boats run fine the way you set them up. I may not agree with some of your techniques is all.

Mark

[CraigP]

Mark, that’s what’s great about the sport! It’s about bringing a vision to life, and seeing it go. But just for info, I did fixture up my lip seal modification and tested it to 50psi. The scroll pump effect is way below that pressure. Many don’t believe me, but I don’t lose grease out the back. But I developed the seal because I do not like getting into the grease that often. And, I am concerned about pumping grease into the water and adding to pollution. I got kicked off some ponds in my early nitro days for leaving oil stains in the pond. Folks don’t really like that.... Can’t say that I blame them.

[rol243]

For my shaft lube i am very impressed in Chainsaw Bar Lube, this oil stays on the shaft very well and water doesn,t seem to displace it atall. after 4 race runs when i remove the shaft it is still quite oily . i have tried grease but its not as good.

[CraigP]

I’ve heard good things about that chainsaw lube...

[rol243]

Just thinking about these floating brass bushings for the struts, i have always used the lead teflon bushings but only now getting into electric i have started to try the floating type by speed master. now what is the reason to have the rear of strut drilled out larger in diameter to accommodate the nail head part of bushing ? why can,t the bushing but up to the end of the 1/4 inch brass log which goes through the strut ? there is zero contact made via the prop drive dog to strut end thanks to the 3/16 inch gap between both. This floating bush will float from the strut end to the drive dog end freely when in motion and is not subject to any drag atall. ???

[785boats]

Roland.
They certainly can be set up the way you describe. I actually have a few like that. But I just prefer to have the bush recessed into the strut. Keeps the prop closer to the rear of the strut.

[rol243]

Thanks Paul, i just modified a cheap Hobby King strut that had cheap lead teflon bushings by tapping out those bushes and just sliding in some 1/4 inch shaft log , the speedmaster floating bush is a perfect fit . i am going to leave about 1/8 inch of the log protruding out from the strut as theres not enough meat to drill a recess in the rear for the new bushing head.

[Old School]

Thankyou all for your guidance. Like 785boats I do not like an unsupported stuffing tube so I intend soldering a short length of 1/4" tubing protruding approximately 3/16" outside the 9/32" stuffing tube. The slightly protruding tubing will fit inside the strut tube and hopefully still allow a little angle adjustment. A short length of 7/32" tubing (maybe 1/2" long) will be soldered inside the 1/4" tube to support the flexshaft where it is not supported by the teflon liner. Where the stuffing tube enters the strut tube I will seal off with shrinkwrap tubing.

Of cause all this may change once I actually have the strut in my hands (still enroute from the States).