Straighten Prop Shaft in the boat v drive

[kcpilotpat]

I have a vibration on a 2001 sunsetter 21.  I put a dial indicator on the prop shaft. in front of the strut I had .003 runout.  Just in front of the prop I have .035 runout. It looks like it's a b**** to pull the shaft.  It's hard to get to the coupling under the Walters V drive.  I'm considering trying to straighten the shaft using a hydraulic jack to push up on the shaft. I would do it slowly using the dial indicator to measure the deflection and sneak up on it. Has anyone in the group tried this? Is the shaft easier to get out than it appears to replace the shaft or have it professionally straightened? All input is appreciated.  I'll post photos and experiences either way. 

Pat

[formulaben]

My 2 cents: yes, it's absolutely not fun removing the shaft, BUT if you do, it's an EXCELLENT opportunity to upgrade to a dripless shaft seal (zero maintenance), new Cutless bearing (probably needs to be done anyway), and rudder bushing (if needed; mine was smooth like butter afterwards and definitely needed it.) 

Keep in mind that you'll also need to do a shaft alignment regardless of which option you take after the "fix."

[oldjeep]

8 hours ago, kcpilotpat said:

I have a vibration on a 2001 sunsetter 21.  I put a dial indicator on the prop shaft. in front of the strut I had .003 runout.  Just in front of the prop I have .035 runout. It looks like it's a b**** to pull the shaft.  It's hard to get to the coupling under the Walters V drive.  I'm considering trying to straighten the shaft using a hydraulic jack to push up on the shaft. I would do it slowly using the dial indicator to measure the deflection and sneak up on it. Has anyone in the group tried this? Is the shaft easier to get out than it appears to replace the shaft or have it professionally straightened? All input is appreciated.  I'll post photos and experiences either way. 

Pat

Seems like a good way to break something.  Not sure that you should actually be able to straighten the shaft even out of the boat.  Bent = replace.

[justgary]

Check the strut to make sure it isn't bent as well.  I suspect it would bend before the shaft does, and may be a large part of the problem.

After straightening a whole lot of aluminum arrows back in my archery days, I would say that you could certainly straighten a prop shaft.  You could make a roller stand with some ball bearings and use a dial indicator to test for straightness. 

As an alternative, you could turn it between centers if you have a big enough lathe.  Turn it relatively slowly and use a marker to find the high point.

Find the high point and gently bend it on a press stand.  Rinse and repeat.  It goes pretty quickly once you figure out what you are doing.

I suspect you could do it on the boat by lifting vertically against the strut, but that assumes that the strut is where the bend is.  Your dial indicator in a variety of locations along the shaft will help you know if that is true.

[BlindSquirrel]

It's not that hard to remove, especially for a Kansan. Below is when I removed mine, and how I did it. +1 for the dripless shaft seal upgrade.

 

[Woodski]

Not only do you risk breaking / bending non related parts (strut, cutlass bearings, V drive output brg, seal), the ability to actually hold the boat solidly enough to bend a solid 1.125" steel shaft is remote at best.  You could probably lift the back of the boat and not bend the shaft.  As others suggested, remove it.  Good luck.

[kcpilotpat]

Thanks for the input.  The photos of removing the shaft are helpful.  If I pull the shaft I will replace the cutlass bearing and install a dripless shaft seal. The strut appears to be straight.  I have watched several videos on aligning the coupling and it looks tedious.  The access is poor to the coupling.  It's in just the wrong place between the rear seat and the engine compartment. I'll post photos of the set up and progress. 

[formulaben]

9 minutes ago, kcpilotpat said:

I have watched several videos on aligning the coupling and it looks tedious.

No doubt, it's not a lot of fun, but when you're done you will have eliminated a fair amount of future maintenance.  Just get a nice Class D life preserver (or 2) and use that as a firm pillow to lay your chest onto against the seat rail and get comfy while you do it.  Absolutely have a helper handy since it's a bit of a pain to get in and out of position and grab tools, nuts/bolts, etc.  IIRC I had to buy a specific socket for the shaft nut. 

My only other firm advice is to use the socket trick to remove the coupler.  I bought a fairly expensive (non-refundable) coupler remover (as in this video) and due to the design of the v-drive it wouldn't fit in the area of the coupler, so that became a nice paperweight.  The alternative socket method that he mentions worked great and only cost the amount of a few bolts and nuts.  You simply put in the largest socket that will fit into the coupler and using your new longer bolts tight it up to push the shaft out.  Below is a short video to demonstrate it.

Also, while you're down there it's not a bad idea to put a wrench onto the nuts that secure the shaft log.  It's a long blind reach with very low clearance, so a ratcheting closed end wrench with a pivoting head is the ticket here; I can't recall the size.  I just happened to think to do this when I did this mod and mine were ridiculously loose. 

 

 

[justgary]

4 hours ago, Woodski said:

You could probably lift the back of the boat and not bend the shaft.

Good intuition, Woodski.  I just calculated the deflection of a 1.25" stainless shaft held 9" away from a 3,000 pound load.  The deflection would be about 0.22 inches or so, which is no doubt way under the amount needed to induce plastic deformation (i.e. create a permanent bend in the rod after the load is released).

[kcpilotpat]

 I ran the calcs and I got a different number.  The shaft is 1.125 I assumed a yield strength of 100,000 psi.  moment=yeild(I)/r  moment = 14,000 in lbs. at 9" 1500 lbs will yield the shaft.  did I do it wrong?

[justgary]

11 minutes ago, kcpilotpat said:

 I ran the calcs and I got a different number.  The shaft is 1.125 I assumed a yield strength of 100,000 psi.  moment=yeild(I)/r  moment = 14,000 in lbs. at 9" 1500 lbs will yield the shaft.  did I do it wrong?

I did use a 1.25" shaft for some reason.  Never do math in public!

[kcpilotpat]

Well, you were right about not being able to straighten the shaft in the boat. It only sticks out of the strut 4 " or so.  It lifted the whole boat and trailer.  I didn't like that it was lifting the boat and trailer with just the strut. So, out with the shaft, just getting started on that task.  I will install the dripless seal.  Where can I get the shaft and cutlass bearing?  I key word search pops up Bakes, but then it is no longer available. 

https://drive.google.com/file/d/12UR3xjINwFJLl2FX5RyMCzxf73VZbJw7/view?usp=drive_link

[Nick55]

Www.Skidim.com for the plastic cutlass bearings (way better than the rubber), and goretex packing unless you just have to have a dripless seal.  

Could try taking measurements of the shaft and contacting Great Lakes Skipper or Bakes. But most of the time the shafts can be straightened (as well as struts).  To be honest, the strut and prop usually bend way before the shaft does.  

Here’s some videos, the first is on a direct drive shaft removal, but it’s good to see how it works because you are limited in access on a V-drive. 

https://youtu.be/_qBaSVx7tcg?si=qV1owjqOoOdnj98q

https://youtu.be/NkzStf_91fs?si=0hfo3Xy_cPA7yNix 

https://youtu.be/wruAOHYFN1s?si=WaZ74t0k8oOc6XIS

[kcpilotpat]

I watched the videos, thanks.  The vee drive is much more difficult to get to.  

The strut looks ok.  should I remove it also?  If it's bent it will really mess with the alignment of the drive coupling.  I was going to pull the shaft just a bit and if the alignment was good or close I was going to assume the strut was not bent. 

Once pulled i was going to check the price of new shaft compared to straightening it.  I work with machine shops frequently.  The shaft is defiantly bent, about .050 runout aft of the strut.  Forward about .003 runout.

Pat

[justgary]

It should be pretty easy to sight past the rudder and see if the shaft and strut are aligned with the tracking fins.  The strut would most likely bend to the port side, which would make the shaft end jut distinctly toward port.

This thread has a few photos that might help:

 

[Nick55]

My opinion, straighten the shaft, then use that as a guide for determining how to address the strut as you slide it in and out of the strut into the bottom of the boat.  (I’ve always thought a laser would be awesome for this). It should move in with minimal “knocking” into center of the packing base.  You can usually use a flashlight and see how it slides into the base (left, right, up, or down contact) and the. You can actually use the shaft to make small adjustments (use it as a lever, LIGHTLY). Get that to be 95%, then slide the coupler on the end and push it up to the transmission output flange.  That will tell you how far off the engine alignment is. 

[Steve B.]

You'll get it right. Not sure if it was mentioned, but the strut should be verified straight and square too.

[williemon]

What caused it to get bent? 

[kcpilotpat]

No idea how it got bent.  It was a rescue boat from Boat Angle. It sat for 2.5 years. It was inside so the interior is nice.