07-27-2010, 10:23 AM #1
Intteresting point on the Through-Hull Bearing
Being new to the components of the drive system and having to replace my pump and drive shaft recently I noticed something in the Clymer Manual that may be confusing to some new to these things also so I thought I would post it.
The Clymer Manual states the following:
Turn the inner race of the bearing housing with your fingers, feeling for roughness and/or looseness.
With this component being referred to as a bearing housing one might be led to believe that they are going to find roller bearings inside of this housing such as the bearings that are installed in the stator. That is not the case. The inner race of this component is actually pressed in permanently and does not roll. The drive shaft spins on the race while it is heavily lubricated with grease. You are actually turning the entire bearing housing in one hand while checking the race with your fingers on your other hand when inspecting it.
To me, and correct me if I am wrong, the through-hull bearing is a counter balance for the drive shaft to stop excessive vibration and run-out of the drive shaft inside the hull.
I thought it was something that should be up for informational purposes so that someone new to it such as I am wouldn't think that they have a seized bearing if they tried to spin the race inside the housing and noticed that it didn't move.
07-27-2010, 10:51 AM #2
It's a screw-up in the book.
Almost every other "Conventional" drive shaft seal I've seen, uses a roller bearing in them. Polaris uses a couple bushings inside the seal pack. I guess their thoughts were that the bushing will have a very low chance of seizing/rusting on the the drive shaft since there is a gap filled with grease.
Back in the day (pre-1995) Seadoo's uses a seal pack with a roller bearing, mounted onto a rubber coupler. People would neglect to grease them, and then they would seize up while you were driving around. When that hapens... it would rip the rubber mounting boot, and leave you with a 2" hole in the bottom of your ski. And, as you can imagine... that will cause it to sink very quick.
The bushing that Polaris uses will wear quicker... even with proper maintanance... but there is a lower chance of a catastrophic failure.
FYI... Seadoo now uses a carbon seal that is almost impossible to get a failure on... but they leak air, and cause bad cavitation if not looked after. (very safe, but has a short life)
07-27-2010, 01:12 PM #3
It turned out to be a very expensive learning experience. I just figured I would post this information because those that are new to it as am I, will see the word bearing in there and think that they have a problem when they take the thing out and find that there are just two pressed bushings in there. (I thought I had a problem when I first stuck my finger in there but realized quickly that the thing is manufactured that way.) Hey....that's pretty funny.
The other thing that stood out in the Clymer Manual that made me sure it was supposed to be that way was the mention of a metallic color to the grease. That would be a sure sign that the bushings had worn away onto the shaft.
I wonder how many people don't grease that thing after every single ride? If you don't it certainly will not last very long and the thing is about $90.00 to replace without the seals.
07-27-2010, 01:33 PM #4
I grease if I know they are going to sit for more than 2 weeks (to push out any water that may have gotten into it) or every other tank of fuel. So... on average... I grease every 2 to 4 trips. BUT... unlike most people... I have my seal pack off as part of my winterizing. (clean, dry, and replace parts as needed)
And just an FYI... you can get a seal and bushing kit for about $24 to rebuild your carrier.
07-27-2010, 01:48 PM #5
07-27-2010, 06:42 PM #6
Yeah... I too was half expecting some sort of bearings in my seal carrier and was surprised to find pressed in bushings. Well actually, in my carrier the bushings had come loose and were floating in the grease void in the middle. Boy did it leak! Haha. After I realized how this simple carrier was designed... I was able to reseat the bushings and replace the seals. No more leaks.
I don't believe this seal carrier (through hull bearing holder) is any sort of counter balance to the driveshaft. The driveshaft is supposed to be perfectly straight and as such there really shouldn't be any vibrations from it just spinning. Now if it's bent or if the shaft is misaligned from engine-to-jetpump...then yeah... that will likely cause some vibes.
The seal carrier is just designed with it's two bushings to stay as centered/aligned with the driveshaft as possible. This gives the two seals on either end the best possible seal against the driveshaft as one holds back the water and the other holds in the grease. Then the tube/big-hose connects the seal carrier to the hull. Simple yet effective.
07-27-2010, 06:47 PM #7
07-27-2010, 06:49 PM #8
Yep the seal carrier is only there to prevent water intrusion. Steel bearings and salt water = sink. Brass bushings are the way to go.
07-27-2010, 07:51 PM #9
If brass is the way to go, let me know where to get them and the exact size and I will give it a whirl.
Note: I thought that the bearing was used as a counter balance because I also read in that same manual that it is used to stabilize the drive shaft. I am finding out that a lot of information printed about these machines is inaccurate. It also occurred to me that to keep water out of the hull a seal could have been inserted and mounted right in the hull that would work in the same manner and principal. I guess there is a good reason why it was not manufactured that way.
07-27-2010, 08:05 PM #10
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