Aqua Drive and Shaft Alignment

[wingover]

Hi,

I have an Aquadrive bearing system and I notice that I have some vibrations. When I looked at the shaft while underway I noticed that my shaft is going a bit up and down(or left and right) where the PSS shaft seal is. My shaft is not bent as this was looked at.

Does this indicate a problem with my cutlass bearing? I don't think you can align the shaft when you have an aquadrive flex drive??

Thanks

[boden36]

Possibly the cutlass bearing, but I would first check the rubber bushes each side of the two bolts which locate the thrust bearing on the inboard end of the shaft. The bolts should be tight enough to be squashing the rubber a bit.
Regards, Richard.

[wingover]

Hi Richard,

Thanks for the reply. I looked at them and they are ok (and fairly new). Also the shaft looks fine in that area (no wobbling).

Is there a way to know if it is the cutlass without diving?

[boden36]

I suppose you could grasp the shaft inside the boat and try to pull it up and down or arrange a short bit of 2x1 timber to lever it up and down or maybe lever the prop with the end of an oar or boathook whilst someone observes from inside. Is it possible your shaft may have started to crack and is flexing?
If it is wobbling lots due to a worn bearing, you would think it would be noisy.
Regards,
Richard.

[Steve Pope]

they are supposed to be missaligned, (the allowable ammount depends on the gearbox reduction) this allows the grease to do its job.
If there is nothing loose or obviously wrong at the inboard end I would suspect a dirty prop (barnacles) of failing cutlass bearing

[S/V Alchemy]

There is a thrust bearing in the AquaDrive installation. If this is bolted to stringers/frames, there could be play from that.

[s/v Jedi]

With engine off, put gearbox in neutral. Tape a pencil to the hull so that it's tip touches the propshaft between thrust bearing and PSS seal. Now, turn shaft by hand while checking the pencil tip.

Bend shaft will show up this way. If this test shows straight shaft, there are 3 possible causes:

1. thrust bearing
2. cutless bearing
3. propeller

My 1st guess is a fouled prop.

ciao!
Nick.

[James S]

I'm also thinking the fouled prop...its the most common cause...and thankfully the easyist to correct.

[wingover]

I had a diver cleaning the prop a few weeks ago but didn't check the cutlass. So I am thinking its not the prop. I'll do the pencil test

[Mark Johnson]

I also have an Aqua Drive AND PSS shaft seal. Since the double U joint "flexible" part of the Aqua Drive is only the part between the thrust bearing mounts and the engine, the other half, that clamps to the shaft, should spin ONLY, and not move around AT ALL. If it does you could have a misaligned thrust bearing. This half has to be very accurately aligned on installation, and should then stay that way. (Ours has for 15 years). If it is not that, and the shaft is not bent, Then I'd next check the play in the cutlass bearing. (1/32" - 1/16" MAX)

If it is not that either, then perhaps the bearings on the Aqua Drive are worn??? See if you can manually move the shaft up and down...

Good luck!
Mark

[S/V Alchemy]

That's a nice installation, there. Almost identical to the one my friend's done, and very close to the one I will be doing shortly.

[wingover]

Hi Mark,

Thanks for the picture. My setup looks the same too. the end of the shaft where it connects to the aquadrive spins fine with no vibration. I can only see the PSS area going out of round.

Should the cutlass bearing be the problem, do you put a new one in and than align the shaft to it? once this is okay do you than move the thrust bearing up or down to meet the shaft?

[Steve Pope]

The PSS can appear out of round without being a problem, it depends on the way the clamps holding it onto the shaft are tightened as to whether it runs true or not. Obviously the truer the better, It doesn't necessarily mean that the shaft is out of line or bent etc.