happy hours

I have 99 Volvo SX drive and have a very slight vibration while straight ahead and a fairly large one when the drive is turned right of left with power applied. The U joints are new and the gimble seems totally OK. When I did the Ujoints it actually seems to make it slightly worse. Yikes. I have tried 2 props and have Julie at Throttle up re-do one and I am sure it is not prop related. I checked the alignment and it seems OK too. ( I don't think alignment can cause vibration anyhow......just kills couplers...correct?) I am replacing the gimble bearing anyhow since it apart and while doing that I noticed the drive shaft that engages the coupler has some wear where it slides through the gimble bearing. It looks like a typical surface hardened thing that has the upper layer hurt, slight pitting and granular looking. It looks worse as you get farther away from the o-rings. Is that where it rides thru the gimble bearing while you turn since the axis is rotation is outward? I am going to mic it tonight and see if it is under sized as compared to my alignment tool. I think the alignment tool is supposed to be 1.375 exactly. Also both the little o-rings were quite beat up. I assume that are for grease retention only and have no effect on side clearance. Anyone have any clue what might have caused the shaft to wear? Think this is the cause of my vibration? I hate to throw a 200 dollar part at it and have same issue.

88Fount33

I had vibration similar with my antique Fountain with B/W trans, tail shaft, and TRS drives. I too replaced my U-joints to no effect, then had the shop pull the port engine and check out the trans and tail stock (where the gimbal bearing mounts) I did not have the shaft wear but all the bearings were bad in the tail shaft and the one in the front of the tail shaft had seized with the coupling extention turning inside the bearing race until the bearing freed up and started spinning again. Replaced all the bearings and seized shaft, but have not water tested as boat is still in shop.
I would replace the gimbal bearing right away and then water test. Are there any other bearings between the coupling and the drive supporting the drive shaft on Volvo? I was amazed that mine had three (one being what is referred to as the gimbal bearing)!!