CV Joint / Drive Shaft

[stillbuilding]

Well, it is said that there are no stupid questions so here goes.
I have a Perkins 135HP pushing a 2.43:1 reduction gear to a 26" prop.
I would like thrust block and cv joint/flexible shaft connection. Looks like Python Drive, Aquadrive or Orion units. Which are fine but seems outrageously expensive for what is a very simple and old technology.

Is there any reason why I could not use a heavy duty auto CV joint/shaft which are sold for peanuts in comparison? I imagine there are autos which have torque and wear solutions far greater than needed for my little diesel.

[atoll]

no reason not to,but make sure you have a high quality thrust bearing on the prop coupling side.

we used a landrover fwd drive universal joint and a skf bearing mounted on a cross bearer glassed to the hull.

also make sure to leave plenty of room to repack the stuffing box.

[stillbuilding]

Originally Posted by atoll

no reason not to,but make sure you have a high quality thrust bearing on the prop coupling side.

we used a landrover fwd drive universal joint and a skf bearing mounted on a cross bearer glassed to the hull.

also make sure to leave plenty of room to repack the stuffing box.

This sounds practicable - easier for me to do in steel than glass I reckon. Thanks.

[atoll]

steel or glass depending on hull material.

just remember the bearing has to take all the thrust when in fwd and reverse so bearing and cross bearer must be robust as 135 hp engine creats a lot of force.

you might also think about incorporating a shaft generator into the design if the boat is a sailing vessel.

like this;

[stillbuilding]

Originally Posted by atoll

steel or glass depending on hull material.

just remember the bearing has to take all the thrust when in fwd and reverse so bearing and cross bearer must be robust as 135 hp engine creats a lot of force.

you might also think about incorporating a shaft generator into the design if the boat is a sailing vessel.

like this;

Hmmm, nice. Thnks

[Mark Johnson]

Originally Posted by stillbuilding

Well, it is said that there are no stupid questions so here goes.
I have a Perkins 135HP pushing a 2.43:1 reduction gear to a 26" prop.
I would like thrust block and cv joint/flexible shaft connection. Looks like Python Drive, Aquadrive or Orion units. Which are fine but seems outrageously expensive for what is a very simple and old technology.

Is there any reason why I could not use a heavy duty auto CV joint/shaft which are sold for peanuts in comparison? I imagine there are autos which have torque and wear solutions far greater than needed for my little diesel.

I chose the Aqua Drive unit. It is more than a "U" joint. First off it has a thrust bearing that delivers the propulsion thrust, as well as the stresses from snagging a crab pot, to the engine bed, RATHER than the engine, it's rubber feet, or it's bearings.

Then it has TWO "U" joints, connected together by a short TELESCOPING shaft, all inside a rubber bellows. This allows the engine to be way out of alignment, and move all around, even for and aft shaking, without moving the prop shaft at all! The shaft just spins... This feature makes a dripless shaft seal, like my PSS, work infinitely better.

Together, these features make the engine's feet, bearings, and the shaft seal last much longer. It also makes it where engine to shaft alignment need not be constantly monitored or adjusted. Original alignment is much easier two.

We installed our engine within 5 degrees, 16 years and thousands of engine hours ago, and have never touched the alignment since. Although I may change the soft Yanmar rubber feet soon anyway, they have no sign of wear.

At the time, we paid $700 something for the small Aquadrive CV joint. While I could have cobbled together "something" cheaper, I could not even come close to creating something as utilitarian and long lived as this unit, for that price.

If you want one, buy it... IMO, it's a good deal!

M.

[S/V Alchemy]

While I agree with the above and will be installing an Aquadrive unit shortly for precisely the same reasons (it's a steel boat and the reduction in vibration makes a HUGE difference), the OP can't use the "small" CV joint, because that's limited to 75 HP, if I recall. I have no idea what the "next one up" costs.

Nice installation, by the way.

[stillbuilding]

I do understand the benefits of the system. Just checking out options before committing to the substantial outlay.

[atoll]

check out these guys for shaft bearings etc,also have pss aquadrive etc thogh not on the web catalogue
HostWeavers server - Lake Engineering manufacturer stern gear and marine propellers for yachts and boats.

also Welcome to Lancing Marine

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[stillbuilding]

I am considering a change in transmissions with a resulting 7 degree misalignment. Anyone know if this is acceptable in real life situation?

[goboatingnow]

Halyards Aquadrive will handle that


Dave

[DeepFrz]

Aqua Drive give a life expectation for the different units at 3 deg. misalignment. You would have to check with the company to see what 7 deg. would do.

[S/V Alchemy]

The point of an AquaDrive, to my understanding, is not to facilitate a permanent and intentional misalignment, but to allow transitory misalignments due to vibration-reducing "soft" motor mounts in a seaway.

A second feature is the isolation of the drive train from the prop shaft via the thrust bearing and the "cushioning" effect of the CV coupler.

Yeah, I have a steel boat. Seeing a soft mount/AquaDrive on a friend's boat and "not hearing it much", I was convinced. I'm doing the install over this winter.

I intend to labour a fair bit to get "zero degrees" dialled in. In other words, the engine at rest will be mated to the AquaDrive coupler as if it were a solid coupler. Then, when I get smacked by a wave while motoring off a lee shore and I'm heeled 30 degrees, I won't worry about alignment! That's how the CV joint should be, to my mind, employed.

Of course, I still have to watch my oil temperature running the engine at heel angles, but at least I won't bend the transmission linkages.