Just how much play should there be in a gimble bearing?

[NoWorries]

I have had a slight rattle in the drive when turning sharp or at high trim angles on my Bravo III Merc. So, I replaced the gimble bearing with a new sierra bearing, with everthing done by the book. Took the boat back out, and at first the problem was fixed, but the more I ran, the more the rattle came back to the point that it is now actually worse than before.

While working to replace the bearing, I slid the old bearing onto the drive shaft and twisted the bearing back and forth noticing slight movement. (about 1/16" at most) I then took the new bearing out and did the same test, with the same results. You can't really see this play by just moving the bearing in your hands. It has to be slid onto the drive shaft or alignment tool to really see the play.

Is this normal? Or did I buy a crap bearing? I'm currently planning to order new u joints, as this is the only next step I know. But, my u joints looks and feel perfect. No play in any direction. Only clean grease comes out when greasing them, no water or rust color. No water in my bellows either.

 

[Don S]

Re: Just how much play should there be in a gimble bearing?

I'm not sure where you are seeing this play, but sounds like it's between the shaft and the bearing, if that is the case, there should only be a few thousands gap between the two (they do NOT fit tight on the shaft) but not 1/16"
Your sound is probably the ujoints. When you take them apart you will find groves from the needle bearings worn into the cross piece, and when they first start making noise, they do sometimes still feel good.

 

[Kevin70]

Re: Just how much play should there be in a gimble bearing?

Don, I think he is talking about play between the inner race and outer race of the bearing, and he can only feel the play when the inner race is "anchored" by a shaft.

 

[NoWorries]

Re: Just how much play should there be in a gimble bearing?

Yes, Kevin that is what I'm talking about. It's almost impossible to see this movement by holding the bearing in your hands, but it's plainly visible with the inner race on the shaft or alignment tool.

I had the same rattle from my previous boat with a pre Alpha drive. I replaced the gimble bearing and it was silent once again. Now this boat has the same rattle, but the gimble bearing didn't fix it. The old gimble bearing from the pre Alhpa drive, the old bearing from my B III, and the new bearing I just put in all has this small amount of play when rocking the outer race back and forth. That's why I have suspected the bearing to be bad. I am going to replace the u joints no matter what, at least for peace of mind. I just don't know if I should go on and order another gimble bearing and replace the "almost" new one.

 

[DHPMARINE]

Re: Just how much play should there be in a gimble bearing?

Just a point or two .... when you removed the first bearing,you damaged it,just by the nature of the way it has to be removed.

So comparing it to another bearing should be a moot point (apples/oranges).

Mercruiser has one bearing for Alpha drives and another for Bravo drives.They look the same,but have different part #'s and prices.I trust they are different inside,but don't know.

Sierra site won't work for me right now,so I don't know how they handle this.

I like Sierra products,but maybe you need to compare with a New Mercruiser part at this point.

DHP