Shaft Alignment Anxiety Attack!

[Derek Hewson]

Just installed brand new (yet built five years ago) unit that Don built! All has gone well until it came to shaft alignment that sent me into a panic.

1979 Catalina 30
New Stainless Shaft Installed two years ago
Prior setup had shaft running perfectly true
Boat is in the water through all of this

I did not remove coupler myself (I have a cast on my arm) but was told that when it disconnected there was a noticed "drop" of the prop shaft as they separated.

Aimed/aligned engine to shaft coupler with shaft in a static (at rest) position. (No good?!)

Here's my question:

We mated the coupler's together with feeler gauges and had what seemed to be a perfect .022" all the way around between couplers before bolting together. After putting the boat in gear, I have a very distinct "wobble" at the stuffing box. Does this mean a "bent" shaft?!!? Because thats what it looks like...

PLEASE PLEASE PLEASE, anyone that can shed light!!?? The old motor was only slightly hung up on the output shaft center nut as we puller her out. Would that "bend" anything!?!?!

Can you have a wobble just from misalignment?? (please say yes)

[Dave Neptune]

Yep

Derek, if it wobbles it's not straight. If it is misaligned it should still turn but not wobble as the shaft would flex. How thick is your shaft? They can be straightened by "peen straightening" a common practice. Just note the area where the packing and strut ride and don't peen in that area.

I have done this leaving the boat in the water by just plugging the log hole when sliding the shaft out to a diver/friend.

How much of a wobble? If you can stick her in neutral and rotate by hand. You can use a good ruler and measure from a "fixed point" the wobble at the hi and low then post what you see. It can be done more accurately with a caliper depth gage or an indicator. The ruler should work fine if you have good visability.

Dave Neptune

[Loki9]

I'm going to disagree with Dave, a misalignment can cause a wobble.

It's also unlikely that you bent the shaft during the engine removal.

When aligning the motor you may need to support the shaft so that it is centered in the shaft log and not flexed at all. I think aligning the motor with the shaft hanging freely (after a noticeable drop on disconnect) may be your problem. Try the alignment again.

[Derek Hewson]

Getting closer?

Getting much closer, ( I think ) in that after glossiness the couple bolts I have minimal wobble. Tighten it up, more wobble....

(Shoot me!)

[Derek Hewson]

Thats "loosening" the bolts ( doing all this with a cast up to my shoulder!!)

[Derek Hewson]

Dave,

Shaft is standard 1" but Stainless steel

[Dave Neptune]

1" is tough to bend!! Are you sure the shaft is "centered" in the coupling?

How much wobble and does it cause a lot of vibration?

Between the strut and the coupling things should be "straight". Do you need to hold the coupling up or down when inserting the bolts? Or if you are sliding the shaft into the coupling same question are you needing to hold it in any direction?

With that shoulder don't get the cast wedged in somehow.

Dave Neptune

[hanleyclifford]

IIRC the Cat 30 has a fairly long shaft. When disconnected from the engine the shaft will drop and then not be true in the cutless bearing. The first step is to get the shaft back true in the cutless. Disconect completely from the engine. Grasp the coupler on the shaft and swing it around observing how high, low, port and starboard you can swing it. Now intuitively find the center of the circle you have just defined. Prop up and support the shaft in this centered position. Only now start moving the engine to the shaft - not the other way around. In other words, bring the dog to the tail. The allowable deviation is .003". Your .022" is way off.

[edwardc]

...We mated the coupler's together with feeler gauges and had what seemed to be a perfect .022" all the way around between couplers before bolting together. ...

???? This shouldn't be possible. At some point on the circle, the coupler faces should be touching. It almost sounds like your shaft is protruding beyond the coupler face, peventing the faces from coming together.

[Loki9]

???? This shouldn't be possible. At some point on the circle, the coupler faces should be touching. It almost sounds like your shaft is protruding beyond the coupler face, peventing the faces from coming together.

I think Derek is saying that he aligned the coupler faces when they were 0.022" apart (that much space all the way around) and then brought them together.

The more typical alignment method is to bring the coupler halves together until they make contact. If they are not aligned perfectly, there will be a single point of contact and a gap on the other side. Measure the gap and adjust the engine's position. Measure again and repeat until the gap it 0.003" or less.

[Derek Hewson]

[QUOTE=Loki9;83532]I think Derek is saying that he aligned the coupler faces when they were 0.022" apart (that much space all the way around) and then brought them together.



Thank you Jeff. That is exactly what I was wanting to explain. Reason being is that with the surfaces together it seemed as thou there would be no gap whatsoever.

[romantic comedy]

I dont follow. If the gap was the same all the way around, that means that it is in perfect alignment, which equals no gap at all.

[Derek Hewson]

A thought that struck me?

There is much discussion about finding the center point of the shaft in the log. I am wondering if using a feeler gauge at he log might be the way to go?

i.e. find the exact center point for the shaft in the log with feeler gauges with a live center, then align "the dog to the tail"?

Thoughts?

[Derek Hewson]

Correction...

Actually, the correct tool would be a "V-block"....

[Derek Hewson]

I dont follow. If the gap was the same all the way around, that means that it is in perfect alignment, which equals no gap at all.

And there lies my original quandary! Had "separation" of a perfect .022" all the way around with bolts loose, which geometry would suggest, perfect alignment once tight.

Starting to wonder if there might be paint or debris between mating surfaces, thus causing run-out. Today I go down there with my Starrett dial indicator and mag base. The only iron is on the engine, so not sure what I can attach to back near the log...?