Shaft wobblealignment

[firepiper]

"Hello, question on shaft alig

"Hello, question on shaft alignment. I have a vibration and small wobble at the stufing box of my strboard engine. Been there for as long as i have had boat. I've replaced the coupler, and cutlass bearing, still there. Then i had the props checked, still there. With boat on the hard now, I was going to send the shaft out and have it checked for straightness. So, today, when I disconnected the coupler, i found that it wanted to sit lower than it was when mated up. It turns much easier if i lift it up a hair and turn it. This would make me think alignment, ( which I've done sevral times). Do you think I would get a visable wobble at the stuffing box from bad alignment? It is more noticable at slower speeds. I go 20-30 miles across the bay to fish, at cruising speed, I really can't feel it. Any thoughts?"

 

[linesix]

"Sure, even more if you have a

"Sure, even more if you have an intermediate strut or a bearing in the shaft log. Have you checked the transmission output flange for trueness?"

 

[capemaydiamond]

i think it will do that becaus

i think it will do that because when you are on dry dock the fiberglass flexes from the weight and the shaft will not line up properly because of that. i had that problem with my boat. the alignment won't be correct unless the boat is in the water at least that's what i was told when it comes to the larger boats

 

[makomark]

"Its normal for the alignment

"Its normal for the alignment to change after a haulout. The hull isn't floating, it is blocked.

You may want to check the position of the shaft in the log, with the couplers mated (not bolted). If it is more than that "hair" off center, in the corresponding direction, that will cause a wobbling stuffing box."

 

[fastjeff]

"A word on coupler alignment:

"A word on coupler alignment: If that sucker goes on the shaft crooked--which is not hard--then the best alignment in the world is useless.

Learned this the hard way. I too had a wobble, so I pulled everything out. The tradintional "roll the shaft on the garage floor" test said it was straight, so I started looking elsewhwer. My machinist cleaned up both ends of the shaft, then faced off the coupling flange as well. Now I had a flat, straight and true surface to work with.

Also, as capemaydiamond said, alignment on the hard is inaccurate--especially for a fiberglass boat. I suggest you pull the shaft and go through my excercise (as described above). Then, after aligning her in the weater, you'll be all set.

Jeff"