vibration from leg

[174ben]

Hi all, took my boat out on the weekend and developed a minor vibration coming from the drive unit.

Vibratrion is there when cruising slowly off plane and turning slightly left or right. Its also noticable when trimmed all the way down and slow speed.Once moving on a plane at speed there is no vibration at all.

Im hoping someone could tell me is it gimbal bearing? or perhaps U joint? and or how to diagnose...

upon inspection ive now noticed excessive movement, around 1.5 inches left and right of the alpha one leg. Now im very concerned....

Thanks

[mmwjr]

The side play is most likely a worn swivel shaft and gimbal ring. This may also be the source of the vibration. What is the condition of the prop?

[174ben]

Prop has couple small marks that have been there for a few years. Vibration only started on the last trip.

Gimbal ring big expensive job? I’ve started researching and it looks challenging!

[mmwjr]

If the swivel shaft and gimbal ring are bad this would be the time to replace all 3 bellows, gimbal bearing and lower shift cable, yes expensive but common maintenance.

[174ben]

Thankyou. I removed drive, gimbal bearing had a very slight notch when spinning by hand. replaced and greased all good, no sign of any water intrusion. u joints felt perfect, looked clean, all good. Used brass shims and tensioned gimbal ring bolts to take up slack, all good. (temporary fix to get through season), Prob was also sent for full repair.

once re assemblled and tested at home on muffs, vibration still there. only when tilt all the way down and in gear, tested at idle.

[mmwjr]

Hopefully that’s gets you through the rest of the season.