Driveshaft alignment

I've always had a slight vibration in my boat whenever I had lots of people or ballast in it, so this weekend I thought I'd investigate further. I wetted down the cutlass bearing and slowly spun my prop. I found that 3/4 of the rotation is very smooth, but at a certain point there's a little bit of friction. Not a lot, but it is noticeable. I loosened my dripless packing seal and removed the 4 bolts holding the shaft coupling on to the transmission, but I could not get them to separate at all. I even went so far as to bang on the back of my prop to see if I could pop them apart, but no luck. There's no other attachment point that I can see for the transmission-to-driveshaft.

Anyone have any ideas on this?

Thanks

Trash

Hey Trash, what year and make of boat do you have? Why are you pulling your driveshaft? There should be a connection between the drive shaft and the hub, and then the hub to transmission. If you must pull the shaft, loosen the set screws on the hub(2) and your drive shaft should slide out. You may need to use a slide hammer to pull the shaft out of the hub, they tend to pull out with great difficulty. I still don't understand why you are pulling the drive shaft. Is it bent? That would be the only reason to pull it. To adjust the alignment of the shaft out the back of the boat, you need to move the entire engine. Or, measure the pilot bore on the output shaft to the hub. They should be concentric within about .002 to .004 inches. I would place a dial indicator onto the cutlass bushing and measure the runout of the drive shaft before replacing it. I would recommend you measure the runout at the very end out by the prop, halfway up the shaft, and at the hub. If it's out more the .005 to .008", I would contact your dealer to verify the spec. Then,if it's warped, change it out. Your vibration could be coming directly from the prop. Those would be my first diagnosis of the problem.