kawjs550sx

I am still relatively new to boating, but have just finished my first scratch built 3.5 mono. I started the engine up out of the water today to see how the flex drive would respond, because I know that I have a good distance between the engine and the stuffing tube. Just as I expected, there was some deflection of the flex shaft as it ran. At the midpoint of the exposed section of the shaft, there was maybe about a half inch deflection. Is this something I should be concerned about?

racer504

My Feedback: (2)

Yes! You should be concerned. The flex shaft should be totally enclosed in a stuffing tube with a liner of brass or teflon. Only a very minimal amount of the flex shaft should be exposed near the collet.

advanced builder

An old school proverb , No more than the width of your starting belt, between your flex hex & Brass stuffing tube. I have forgotten to put my belt on, more than once.

toyotatruckin

The gap at motor end I usually make sure I can remove the collet end with the motor still in the hull (not the entire collet just the end you tighten down) the belt also works and is close But not always does one run a belt the drive end kind of depends on the drive but should be minimal..

a slight "S" bend in the stuffing tube will smooth out the operation of the flexshaft and kill most all the cable whipping in the tube REMEMBER to much of an "S" bend can do more harm than good(worst case example, rip the drive line out of the hull) hope that helps and if you have any more questions please ask someone here will be glad to help you out!!

kawjs550sx

Excellent, thank you for the information... sounds like it is time for some grand tubing engineering. I was pretty sure that I should be concerned about these things.

Next question, bending the tube into an S... can this be done by gently working with hands. Or, do I need to build a whole jig to bend in properly? Thanks again

Darkseacret

depending on how exteme the curve is you can hand bend it or if its a tight curve or its wrapping a motor can you can fill brass rod or tube with fine sand or sugar ,tape ends shut and bend away

kawjs550sx

Awesome, thanks for the info. Will try that tomorrow

TCHedOff

I see no one has mentioned it: Heat the brass stuffing tube w/a propane torch if you have one. It will soften the metal some, so it is easier to bend by hand.

The brass will blacken some from the torch's propane residue, but you can clean that up.

Ron Olson

My Feedback: (1)

There is a certain brand of flex cable collet that is known to have a wobble in it so check that while you're in there. You'll see it when slowly turning the engine over. The funny thing that it only seems ot be a problem on .21's.

toyotatruckin

Follow what TC said heat the tube and bend by hand, again dont get to frisky with the bends

dicko

One thing to mention also, make sure you keep a gap between the front of the drive dog and the end of the stinger, otherwise the flex cable will shorten under load and cause the dog to bind on the stinger resulting in a snapped flex cable. Usually the width of the flex cable is about the gap you want to leave unless you are running a hydro with a long flex, then leave a bit more.

Blackout

You don't always have to use an "S" bend. In a surface drive mono, I find it better to just use a slight bend in the tube and tilt the motor a little.

Blackout

Here is a picture of the shaft tube on my Speedmaster. There is only a slight bend in the tube and the engine is tilted. With the shaft exiting the transom, an "S" bend would be tricky, and the tube would interefere with the radio box most likely.

kawjs550sx

Again, all excellent information and very helpful. Thank you to everyone here... It is good to know that a forum exists where people are actually helpful. I think I can come up with something that will work well.

Question for Blackout... What type of epoxy or glue is holding down those wooden strips? It doesn't quite look like epoxy that I am used to

Blackout

It's West System epoxy with their 404 adhesive filler added. The color is darker because my hardener is old, but it still works good.

Ron Olson

My Feedback: (1)

Off-topic I know but are you keeping that tuned pipe inside the hull like that?
Here's how I did mine.

Blackout

Yes I am, is heat a problem?

The thing that I hate about monos is when the pipe sticks way up in the air... Your pipe is not bad though.

advanced builder

Blackout, whats that pipe you got in that Speedmaster hull. nice job

Blackout

Thanks, It's a 7.5 Mac Muffled Marine. Here are more pictures.

advanced builder

OK GREAT JOB, can't wait to see her run. I sent some props out to Mark ,props4u.com He does a great job also .
PS Ron, how many hulls U got?? An are they all setup? Great job too WHOO DAT on the hull?? Dennis

toyotatruckin

Sorry it took me so long to get this video up I was in the process of getting my shop set up (again) lol hope this helps enplane whats going on inside your stuffing tube a bit

http://www.youtube.com/watch?v=pwq-3x0nLl8

kawjs550sx

Nice video, thanks... Question then could you run a cable exposed (stuffing tube only where cable exits transom) if the cable has an s-bend in it? For some reason, I think this may still be a bad idea

toyotatruckin

no no you still need the stuffing tube to support the cable!! If you didnt the cable would be all over the place and could actually tear your boat apart, also there is quite a bit of load on the cable when you put a prop on the end of it pushing water- the cable will actually shrink up under load thats why you see the gap between the drive dog and strut on boats..

kawjs550sx

gotcha... Thank for all the help. I remounted my engine and epoxied in the stuffing tube today. Hopefully it works because I am ready to get to the lake. Also, I switched from a collet connection to a universal ball coupler connection at my engine. I thought it would work better for my setup. Any thoughts on this, good or bad?

Ron Olson

My Feedback: (1)

Somehow I lost my subscription to this thread. I couldn't tell you how many that I have right now or how many I've had over the years. There's usually at least a new one every year but working on 3 of them this winter. I gotta hustle as the snow is thawing!
Let's see........
2 JAE ,12's, 1 JAE .21, 3 .12 mono's, a Sport .12 hydro (see a trend here yet?), an Easy-Vee, American RC Boats Vee-Rod, Lazer 45, PHM Pro Cat (Drag Cat clone), Falcon 41 and a Zig-Zag Racer. I sold the Super-Vee 27 Nitro last Saturday. I think that's it for the moment but am waiting for the JAE Gasser to come out. Yes, I'm always in deep doo-doo with the wife.
The Speedmaster .21 was my son's race boat and he did rather well with it. I built a Microburst .45 for myself the same winter.

I'm not crazy about the ball coupler setup myself as you shouldn't use it with a flex cable, only a straight shaft.