Alignment Blues

Im having issue aligning my engine/prop. I called evolution marine to ask about their flex coupling, but was told their product is not for correcting misalignment. strange..

Does anyone know about other flex couplings rated for marine use?

 

You really want to align your shaft properly, flex couplings allow a little room, but only a few thousanths. They're more for peace of mind, I think. If you have a unique installation (offset engine.....) and if you have enough room, you could fabricate an automotive style driveshaft, best done with CV joints, which will take a lot more misalignment. Even driveshafts have to be somewhat aligned, if both universal joints are offset, it will rattle your fillings out.

 

IMHO, flex coupling are more torsional vibration avoidance than for allowing misalignements.

You can find others that will allow engine move on silentblocks with a fixed propshaft. But even in that case, the average engine position will have to be aligned with the shaft.

I absolutely do not stand behind what I wrote. Feel free to correct me.

François.

 

It is possible to install an engine with the drive shaft out of linear alignment with the prop. First it requires the thrust load be transfered to the hull via a thrust bearing and bracket before it gets to the engine output. Properly rated CV joints can do the job. There are thrust bearings made specifically for this purpose. This is not an inexpensive under taking. Properly done this, method and the use of vibration dampening devices (like the Federal or Evolution coupling) can reduce structure born noise considerably. As Corpus said vibration dampening couplings can only take care of a few thousanths of misalighnment and are primarily meant to take care of the slight misalignment that is a result of the movement of the engine on its soft mounts when torque is applied and to reduce noise.

 

Why is it that you're having trouble aligning the engine/shaft? Is the engine too high or too low or is it a side to side issure? All of these problems can be solved at a much lower cost than some jury rigged "flexible shaft" arrangement!

 

Flexible joints-CV, u-joints, rubber, etc- are designed for the intersection of the axis of both shaft to coincide with their center. In other words, if one shaft is higher that the other and their axis don't intersect, the joint would have a lot of side thrust and the shafts would bend. Have you changed the engine or transmission and they don't align any more?

 

Alignment blues II

I recently had to remove the transmission and found the alignment issue. The engine and its adjustment mechanism are pushed as far as possible to one side. No more room exists. The shaft is coming out of the deadwood mounting piece (dont know the name of the piece, the bulkhead side of the stuffing box) pushed far to one side. Behind deadwood is a stainless sleeve, maybe called the stern tube, about a foot long. The shaft seems to be entering the tube from aft, crooked. But the bearing looks fine and is not worn. The other bearing, within the strut is also fine and not worn funny. I would think if the shaft were bent I would have wear marks on the cutlass. I would also think it the shaft were straight, but angled wrong the bearings would wear. Im kind of lost here as to what is happenning. So.. I figured best bet would be a self aligning coupling. Ideas would be appreciated..

 

Borrow a dial micrometer and see if the shaft or coupling is bent.

FAST FRED

 

I agree, before doing anything else verify that the shaft is straight.

 

alignment

If the shaft were not straight, the cutlass would be worn? When I align using feeler gauge, it shows me the shaft is not crooked...

 

Aquadrive..a Swedish firm builds a marine drive which will permit mis-alignment by up to half an inch or 13 mm.C/Vs thrust bearings supplied.no web site i know of though.

 

The cutlass bearing, because it is made of rubber, will allow a lot of misalignment.

 

I have one GMC Ammarine turbo diesel V8 from Grand Banks Laguna in exelent condition (200 hours) but have no informations about RPM,PS......
if anyone have some informations about it .............................
thanks

 

Gonzo, look Vetus or Motomarine web site (.it or .com I am not sure)

 

Aquadrive website is http://www.aquadrive.com