How could this happen?

[zooma]

Third run on a new shaft. Twisted up at full throttle. The only thing I can think of is too much space between the collet and stuffing tube.

Twisted shaft.JPG

[koen]

Hi ron was there enuf space between the drive dog and the stinger/strut?it looks like the flexshaft/propshaft bind somewhere

[larryrose11]

You ARE CORRECT SIR!!
See thee flare on the end of the stuffing tube? The shaft went into a Jump Rope sort of harmonic, and that was the result.

[Fluid]

This is more common than many realize, I’ve seen it often. Ideally there should be no more than 3/8” to 1/2” between the collet and the end if the stuffing tube, especially with high power setups. The stuffing tube should be supported near its inboard end too, not hanging in the air. It’s FE 101.




.

[Johnc]

looks to me the stuffing tube support broke loose (wrong type of epoxy?) then went all to hell after that. And like Fluid said too much spacing between collet and stuffing tube.

[zooma]

Thanks, guys. I like the jump-rope analogy.

And, now for the rest of the story. Last month, at the Atlanta races, on the second heat the motor mount broke loose and snapped the shaft and buggered up the stuffing tube. Part of the repair included removing the damaged part of the tube with a Dremel cut-off wheel. So it lasted for two more heats, but eventually gave out back home at the club lake. Lesson learned.

[larryrose11]

On this, when you make the stuffing tube repair, install a nested tube.
that way, only a short section of outer tube gets glues to the hull.
The actual stuffing tube just slides in.
Makes repairs a snap.

[zooma]

On this, when you make the stuffing tube repair, install a nested tube.
that way, only a short section of outer tube gets glues to the hull.
The actual stuffing tube just slides in.
Makes repairs a snap.

I don't quite understand. The proper size tube is 1/4", to fit into the stinger and hold a .187 shaft without a Teflon liner. So one length goes from the stinger all the way up to the collet. How does the nested one work?

[tbonemcniel]

I don't quite understand. The proper size tube is 1/4", to fit into the stinger and hold a .187 shaft without a Teflon liner. So one length goes from the stinger all the way up to the collet. How does the nested one work?

Put like 1" of the next largest size tube. All the K&S sizes telescope within the next larger and smaller sizes.

[zooma]

Put like 1" of the next largest size tube. All the K&S sizes telescope within the next larger and smaller sizes.

I see