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knocking vibration from alpha 1

sharkin95

Regular Contributor
I'm getting a knocking and vibration noise from the alpha 1 O/D only when turning left or right. what I have done so far is replace the u joints I checked the gimball bearing and it rotates with no drag the only thing left is the coupler any suggestions or another opinion?
 
3 years ago, no water intrusion everything points to the gimbal so I removed the bearing from the race by turning it into the notches the bearing itself seems ok but the race looks a little rough where the notch is. I had a mechanics stethoscope when the outdrive was in and running on the hose and the loudest knock was when I rotated left to right no noise or knocking when the engine was running in gear staying straight the loudest was coming from the bell housing and gimbal area.The splines on the coupler are ok I checked it with my alignment tool. I don't know if it is cocked but I think if it was cocked I would get a knocking even when it was in gear with the outdrive turned straight ahead. this is tough one because the u joints were replaced and I still had the same problem afterwards now the gimbal bearing itself is fine with no drag or bind when I spin it by hand.
 
Your Gimbal bearing can turn freely and feels fine by touch doesn't mean it's not bad, a good bearing will have some resistance when you try to turn it by hand, NOT freely.
 
So I would have to buy a new gasket anyway maybe 12 bucks, to check my gimbal, another 45-50 i have a new one and install it now theres no question as to it being good or not.

U - joints is where i would be looking for knocking in the drive. So you did the right thing with them.

Maybe being ran to high the drive, that's the quickest way to kill the u-joints.

All the pivot point tight ? Grab the drive shake it back and forth like a cheating wife. The holes getting egged shaped maybe ?

All that's left is in the drive.

Quickest way is to drain the oil. Metal pieces are bad.

Then i would think a tooth or 2 went on a gear.

If the engine were overheating or running at high temp and the noise i would consider the impeller.

Alpha 2 there is a bearing in the top cap.

When running even in the water the top cap gets hot.
 
I checked my sterndrive manual and it is possible the race could be causing the problem it is rough on the bottom near the notch. u joints are new, pulled back and forth up down sideways no play. if I had the knocking while the outdrive was straight I would think alignment or upper gears but it only knocks when the outdrive is turned L or R which by right points to the gimbal bearing.I opened the top cover and the gears are good checked alignment with my alignment tool and it shows tooth marks all around. I'm going to try one more thing which is to turn the coupler shaft which I can get to with a pipe wrench if the engine doesn't turn the rubber on the coupler is gone or going.
 
update... I changed the gimbal bearing took all of 45 min. easy job when you have the right tools. started her up on the hose at idle and in gear Same problem hard right or left turn knocking so I took her out in the bay to check if it was the coupler, 3400 rpms 25mi per hr. no smell no slip. made I few turns not all the way over on the turns NO Knocking hmm now I'm really baffled. stopped at the dock turned left and right.. knocking. well I read in a thread of 2 possibilities power steering assist cyl. or the driveshaft that goes in the coupler that holds the u joint carrier is egg shaped. any ideas
 
Inspect the yoke area of the input shaft. look for rubbing at the yoke. Sometimes if a gimbal bearing is not seated all the way it will cause the input shaft front yoke to hit the bearing
when hard over.
 
I agree, there is literally 3 parts that would make that problem first guess u-joints second gimbal bearing third a cocked coupler. I used my gimbal tool to install the bearing so I heard the solid stop sound when installing the bearing, but the yoke might be worn enough to cause movement in the u joint. would you dismiss the power assist cyl as the problem?
 
I agree, there is literally 3 parts that would make that problem first guess u-joints second gimbal bearing third a cocked coupler. I used my gimbal tool to install the bearing so I heard the solid stop sound when installing the bearing, but the yoke might be worn enough to cause movement in the u joint. would you dismiss the power assist cyl as the problem?

Did you ever find the solution to this? I’ve changed gimbal 4 times u joints 2 times checked alignment, it’s spot on, checked drive bearings on upper gears. Gears and bearings look great! Noise is only trimmed all the way down at full lock L&R
trim it up a little and it barely makes the noise.
looking for some help here before I give up
 
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