Shaft saver slipped, shredded the stuffing tube.

[Sean Janne]

Here is a pic of the stuffing tube in my boat after a 30 second first run with the new motor:

By the looks of it, the shaft saver walked it's way down and shred the stuffing tube. It was on tight, I could barely slip it into place and I tightened up the set screw very tight. You can even see where the shaft saver wore away the bronze color on the shaft.

My question is, how did this happen and how can I prevent this from happening again?

 

[Jim Caldwell]

Are you sure the motor collet did not slip?

 

[Rick Doane]

Sean..................Anything you put on the shaft has to be balanced.

 

[jeff baham]

plus the shaft will shrink when under power, did you solder the end of shaft that goes into the coupler, plus you don't need the shaft saver if the coupler is good.

 

[SayMikey]

More pics,how far is the collet from the stuffing tube? Looks like it whipped to me

 

[Brad Christy]

Sean,

I'm with Rick. The shaft saver is not balanced. It's aluminum with one steel screw on one side. This thing vibrated its way down to the stuffing tube and kept going. I'm also with Jeff. Toss the shaft saver over your shoulder, invest in a good collet and forget about it. If you've just GOTTA have the shaft saver, use one that has two screws, one on either side, tapped in opposite directions.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

Model Machine And Precision LLC

 

[Jerry T]

Use a piece of fuel tubing and ditch the shaft saver.

 

[Mike Starrett]

More pics,how far is the collet from the stuffing tube? Looks like it whipped to me

Yep...I agree Look at the marks on the inside of the tubing and the way it's rolled back. Also the stuffing tube is unsupported near the end. There appears to be a lot of exposed shaft up to the collett

 

[Matt Minassian]

I had the exact same problem with that exact same shaft saver. I've always ran the ones gizmo sells that has the set screw screwing into the shaft as opposed to this one how the set screw screws into the collet and tightens around the shaft. I've never had a slipping problem with the gizmo one, switch over to that and rid yourself of those. Everyone speaks highly of the ones you posted a picture of, but I used one once and threw it in the garbage.

 

[Blackout]

I never use shaft savers. Even my gas mono. Never lost a shaft. You do need to know how to properly tighten the shaft and that depends on which collet you have. On my gas collet you need to make sure the shaft goes 1/8" past the collet end as that is where it bites the hardest. If you can't get it 1/8" past on the gas engines, you have to use a low profile bolt to attach the collet to the engine. On my nitro engines, the Octura collets seem to be very reliable. With those, don't bottom the shaft all the way in. Push all the way in and then back out 1/8". The Octura collets grip the hardest at the front of the collet. (Toward the back of the boat).

 

[brad nichols]

I would agree with imbalance, a Durbo wheel collar would of been better or one with the 2 bolts. At 28 to 40 thousand RPM it will vibrate tremendously!!!

Brad

 

[Sean Janne]

Thanks for all of your replies!

The shaft did not slip from the collet, it's still where I set it. I do think that it whipped like someone said, probably from not being balanced, and I did have the collet a bit far away. There's probably an inch from where the picture ends to the collet. Being fairly new, I have seen others run the shaft savers and figured they were what you need to use. The fuel tubing idea is a great one, I will try that on my new stuffing tube.

Since I have to rip this mess out now, I'm going to convert it to surface drive, and will definitely take all of your advice on how to avoid this mess again!

 

[namba276]

DOUBLE SQUARE!!! thats the only way to go...

Bob

 

[Sean Janne]

DOUBLE SQUARE!!! thats the only way to go...

Bob

Sorry, what is that?

 

[bsmtboy2]

Take the previous advise and use Dubro wheel collars. They work well, I also use a Ty-wrap pulled tight around the shaft. Either one works pretty well.

 

[brad nichols]

If you are going to use Durbo wheel collars, it would help to have solder where the setscrew goes on the shaft!

 

[dschigoda]

DOUBLE SQUARE!!! thats the only way to go...

Bob

I can picture the square drive on the engine end of the flex shaft, but how would you do the square drive on the strut end?

 

[brad nichols]

With a square drive, there is no thrust load on the engine bearings. I don't know who makes them but there must be someone who makes the square end ferrel for the prop shaft? The thing about this is you don't lose the prop when you break the cable.

Brad

 

[Mike Cathey]

I think I would be wondering what kind of metal debris my motor inhaled.

 

[namba276]

My buddy Jeff Alvey makes square/square in .150 .187 and .250 He has square drive engine nuts and square drive ferrels. set screw in a stub shaft and you will never lose a prop again. saves bearings too! I run .150 in all 3.5 cc boats...why sling the extra cable with .187? overkill

Bob