CV Driveshaft Experience

[S/V Alchemy]

Originally Posted by stillbuilding

Thanks for that response. My gut feeling was to go for perfect alignment but many people seem to be suggesting that 1 - 2 degrees is necessary for the drive!!?? The thrust block component is one of the reasons I have considered this option. In fact, when funds permit I intend to move to a four blade Variprop also. Nice prop.

Well, I certainly hope so. As it's a steel motorsailer, I want very little resistance under sail, and experience with folders on my other, sportier boat supports this. But under power, I want stopping and maneuvering ability as I have no bow thruster and some windage.

Once I'm at five knots, I don't care. Four blades properly pitched provides economical cruise speeds, but not necessarily hull speed. I'm good with that.

My prop opened and feathered:

[delmarrey]

Originally Posted by stillbuilding

So does that mean 4 degrees minimum for all installations?

Yes! It aids in lubrication. The smaller ones are a sealed unite so the existing grease has to be manipulated.

Sounds encouraging re the noise issue. Had not considered changing shaft alignment issues when slipping but could be a bonus.

It doesn't have to be an exact science. No more feeler gauges, just fairly close.
With soft mounts the motor dances around pretty good but Yanmar says not to change. So until the warrantee is up thats the way I'll go. The rigid mounts are cheaper but do induce more noise, from what I've heard. Besides Yanny mounts are available anywhere in the world.


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[boden36]

We have had an aquadrive for 25 yrs. Have dismantled and greased it once in that time. Motor alignment is not all that critical.
So long as you get the right model for your application, and install it according to manufacturers directions I can't think of a better system.
Regards,
Richard.

[4HMainer]

There are now three double CV/thrust bearing drives as well as two new single CV joints which can take thrust loads. Hydradrive, Aquadrive and python drive and Marine Joint, there is another Italian CV that takes thrust I saw at a recent show but can't recall the name. I know the reason to offset Cardan shaft sis to cycle the bearings these are offset but coplaner by 2-3 deg. Not sure about CV's though.

[sdowney717]

http://www.michigan-europe.com/Trans...-Coupling.html

This looks to be the simplest easiest type to install as it simply fits between the current coupler and is very short compared to the others.
Made of rubbery stuff, so how is the life span?


When you load something like this next one to a big angle, they advertise up to 8 degrees, your pushing a lot of sideways thrust on the trans output bearing which is not good. So regardless, these need to line up anyway. I do like this design as the thrust is still taken by the engine. The others have a thrust plate in the hull that needs to be setup.
http://www.michigan-europe.com/Marin...-products.html

[sdowney717]

Q: Can an Isoflex flexible coupling take any form of mis-alignment.
A: NO - an Isoflex flexible coupling is designed as a vibration dampener only! Any angle / offset misalignment will damage the flexible coupling.

Isoflex Flexible Couplings FAQ

looks like that will fall apart if it is out of alignment.

[stillbuilding]

This Isoflex is a flexible coupling which is quite different from a cv shaft of course. It is precisely the thrust block component which many find attractive.

[S/V Alchemy]

Exactly. When you experience the sort of "clunk" shifting a feathering prop can produce, isolating that from the transmission is desirable in a steel boat. A thrust bearing does that. The rubber "drive-saver" coupler plate is a slightly different beast, in my view, but is still a good solution for many in that it does allow a bit of misalignment and does provide a bit of shock absorption.

[delmarrey]

Originally Posted by sdowney717

When you load something like this next one to a big angle, they advertise up to 8 degrees, your pushing a lot of sideways thrust on the trans output bearing which is not good. So regardless, these need to line up anyway. I do like this design as the thrust is still taken by the engine. The others have a thrust plate in the hull that needs to be setup.
http://www.michigan-europe.com/Marin...-products.html

I would imagine so with only one CV bearing. That's why the better unites have two CV's.