1/4" flex shaft breaking

[Alexgar]

Yeah i think its your gap everything looks a ok

[Gapilot]

Thanks guys. This place has been a treasure trove of knowledge as this is my first boat( in a long time anyway).
Thanks again.

[wayne middlemiss]

the rule is generally the width of the cable, for shorter cables, a shorter gap and vice versa.
that bend looks pretty reasonable.

actualy the stuffing tube bend appears to have an s bend in it which will give troubles, one bend is most prefered to minimise the binding in the shaft. also will hot spot your shaft too creating weak points.

[Boaterguy]

some (mostly gas guys) would disagree about the S bend.

[Gapilot]

It doesn't have an S bend. It looks like it does in the pic though. I think the first break was due to a bad flex since it broke so soon and the one today was more than likely due to no gap.

[keithbradley]

It doesn't have an S bend. It looks like it does in the pic though. I think the first break was due to a bad flex since it broke so soon and the one today was more than likely due to no gap.

Ryan knows his stuff...you'll probably be fine if you run a gap.

If there's not a stuffing tube support just out of site on that pic though, lyou may run into issues there. The stuffing tube needs to be supported near the coupler on the motor or it will vibrate and allow the cable to whip.

[Gapilot]

It has a 4" support glassed in just out of the pic.

Thanks

[drwayne]

Yes for the gap.
If the dog is too close the flex may bind and break free of strut, or worse damage.
Seen it on mine too !!
W

[NativePaul]

In picture 2 what is the ridge about half way down the heat shrink? Does the brass stuffing tube stop there and just the PTFE liner continue into the strut? The brass needs to locate inside the strut or being unsupported for so long it will be free to move and whip around putting high stress on the area where you are breaking them.

While I doubt it is excessive enough to be the cause of broken cables every few runs, it looks like your bend is all in the last 4 inches or so of the flex, starting maybe an inch before the heatshrink. I prefer to make the whole stuffing tube one long smooth bend (apart from the last inch or so before the strut which should be straight to ensure there is no bend right where the flex meets the stub shaft) which makes the radius of the bend as big as it can be.

[detox]

I assume your cable is breaking at the collet? I would check for binding then try to free up. Try lighter viscosity transmission fluid mixed in with your cable grease. Do not solder cable end. If the above does not work....remove Teflon liner.

[longballlumber]

Bend is not excessive. Shaft is 26" long. Brass tubing has Teflon liner in it and seams to be a fairly tight fit, not much bigger than the flex shaft. Cable is turning the correct way. What's the best way to know if the strut is worn?

That statement is a red flag for me. What diameter (OD) of brass tube are you using? I am willing to bet your liner and brass tube combo is too small. I don't think they even make Teflon liner for .25" shafts... Sorry, I stand corrected, I guess Octura does sell a liner for .25" flex.

If it were me I would lose the liner all together.

Good Luck,
Mike

[photohoward1]

It's Breaking at the STRUT guys! He has too much bend to early from the strut. Look at the photos. (Strut then quick Bend.) Gentle with the bends. No Teflon needed but you do have to put in another brass shaft liner to take it's place. Otherwise it will whip in the tube and rob power.

[RaceMechaniX]

I would agree that the bend in the stuffing tube just ahead of the strut is probbaly causing the probems assuming your cable breakage is occuring in the strut end. A simple check, place the shaft next to the strut and line up the drive dog in the correct position with a 1/4" gap. Now where is the joint between the stub shaft and flax cable? Probably somewhere in the bend before the strut.

TG

[JIM MARCUM]

RaceMechaniX knows his stuff. If you get rid of the teflon liner, set the drive dog gap to 1/4" and still have the flex drive seperate from the stub shaft - I suggest you bite the bullet and relocate the stuffing tube hull entry further away from the transom. That will give you the room to put in a stuffing tube with a more gentle bend. I prefer to use seamless stainless steel for my stuffing tubes - it's much thicker & stronger than brass. Here's what the 1/4" drive/stuffing tube looks like on one of my cats. JIM

[photohoward1]

What am I invisible. Looks Nice Jim.