I had a vibration develop in the starboard drive over the past couple of runs - actually I'm not too sure it wasn't there all along, and just starting to recognize it. When I shift into forward or reverse, there is a clunk - the port side does not do this. Again, not too loud, but there is also a vibration when drive is engaged. No vibration when not engaged.

So, last night I went ahead and pulled the drive off thinking it was probably the u-joints, or the gimbal. You guys will have to excuse me - this is my first drive removal so I'm a virgin when it comes to drives. I got the drive off and, the u-joints are floppy, but no lateral play or any play for that matter. None the less, they're not stiff either. NO rust in here at all, and plenty of grease. I checked the gimbal - no galling or binding (as I've read).

Interestingly enough - on the output shaft, just ahead of where the gimball bearing mates the shaft, is polished - is this where the inner seal comes in contact with the shaft (it's on a taper)? I suppose this is normal???

I'm going to order the engine alignment tool to check the coupler next. At the moment, the rubber seems to be OK, but, who knows...

I also pulled the prop off and checked the run-out (visually). No indication of a bent prop shaft. Also, the gear oil is clean... No metal shavings or metal contamination in the oil at all, so it's probably not internal to the gears or bearings of the upper or lower drive???

Any ideas???

Polished sounds like maybe your gimble bearing binding possible due to misalignment. While you are in there check the right front motor mount, it is quite common for them to back down if the tab was was installed incorrectly. Also did you check prop run out, another likely source?

Any prop damage or prop re-work done? I've had props with pitch imbalance (not all blades of equal pitch) cause some pretty bad vibration. Something to consider.

I DID have the props rebalanced. The boat ran it's best - then I brought it in and bounced this prop off the bottom - there IS a little damage to one of the blades (not bent, but a little metal taken out). I cleaned the burrs off with a file and figured it'd be OK but maybe this is the problem???

I'll be picking up the alignment tool tonite so I'll know how out of wack the gimball housing is with the engine...

I didn't check specifically for prop run-out. I will say this - the plastic insert has a crack in it - could this thing be distorted and throwing the prop off balance (I guess for $20 its worth replacing)???

A prop can look fine and be way out causing a vibration.

I would look towards the prop. If you feel the vibration right away, you could swap props from side to side and run the shifters in rev to make it go fwd.. If the vibration swaps drives, then it is the prop. But I would replace that hub.. Check alignment.. Lets us know what you find..

Dick

how about u joints?

Will be putting the drive back on tonite and checking runout on the prop (im guessing tips and barrel)? I did install the new insert (cleaned up the shaft first), the old backing plate / thrust washer was off kilter when the prop came off, but I honestly dont know if it was from removing the prop, or this was my problem (again maybe the insert).

I need to fully diagnose the coupler (rotate 90 degrees around the clock and check alignment), but at the moment, the alignment tool slid right in place. Hopefully I'll know more by tonight.

How did you make out?

Engine alignment was ok. Rotated crank at 90 degree intervals, and obviously coupler is ok. Greased everything up, took two tries to get the drive on (shifter cable not engaging correctly).

Torqued everything down, replaced thrust washer and prop insert, and problem solved. I dont understand how something so simple could make such a clunk... Can understand the vibration. Now the shifting is butter smooth like the other...

Thanks for the support!