Bearing maintenance

[Dan_ed]

Not that there is really much to this topic with the Galibier. If I recall correctly, Thom is somewhat ambivalent on the need to do any of this. But I thought I'd share my experience here. Maybe it will help someone and maybe someone else will think of something I've missed. Perhaps others will simply feel more at ease with how their bearing may be holding up.

After a couple of years I decided it was time to disturb my Gavia in order to change the oil and inspect the bearing. I'm usually not one to put off this kind of thing but as my 'table has never given me any indication of a need to go through this process I don't feel the least bit guilty about the length of time that has passed. Since it was time to break down my system for cleaning, rearranging, etc., I decided to perform the extra steps to pull and inspect the bearing.

It really is a simple, straightforward task. Since I was going to break things down anyway I removed the armpod/arm/cart all in one unit. No sense in taking a chance on having an accident. I also removed the motor pod and belt so there was only the table itself on the stand. From here it is a simple matter of lifting the platter and then unscrewing the bearing housing from the plinth. The only slight complication with this is watching the ground wire while you unscrew the bearing housing. You can either just let the wire twist up or take the trouble as I did to untwist the wire every few turns. Once I had the bearing unscrewed I disconnected the ground wire from the bearing housing so that it was still threaded through the hole in the plinth. This to me makes handling the bearing easier without that wire hanging on, and the bearing housing will stand up straight on its own with that allen screw removed.

Pulling the bearing from the housing takes a bit of tugging due to the tight tolerances but it really wasn't too difficult. Perhaps because my Gavia had not been run for a couple of days so the oil was settled for the most part. I then laid the bearing on a couple of paper towels on the bench so I could free up a hand and concentrate on the housing. I used some more paper towels as a filter and poured the old oil into the towels. No signs of debris there.

At this point I could look into the housing and see the thrust plate, along with the cute little dimple that had formed. Super! Everything exactly as expected. But that worn away Delrin had to be somewhere and it did show up when I began wiping out the old oil. This is when I began to see the light residue left behind from the normal bearing breakin. I used a wooden dowel to push some paper towel down to the thrust plate and then spun the towel to wipe thing up. After doing this with a few fresh towels I could see no more residue (kind of a greyish-black residue) on the towel and almost no oil on the thrust plate. I didn't see the need to attempt removing the thrust plate and considered the job done at this point. I then refilled the lower cavity with fresh Mystery Air Tool oil and put the housing aside for the moment.

Getting back to the bearing itself, I did nothing more that wipe away the old oil as much as possible. The bearing looked bright and shiny. I could not detect any wear on the ball, even with 20X magnification. To be honest I would have been very worried if I had found any signs of wear here.

There are several ways to go to put things back together. I chose to reassemble the bearing and then screw it all back into the plinth after reattaching the ground wire. One could screw the housing back in to place, then add the oil. Whatever works best for each person. I do suggest that before reinserting the bearing in the housing to make sure there is no oil on the shaft above where the ball bearing seats, and no oil on the upper bushing of the bearing housing. This will help get the bearing to seat a little faster because the air can escape easier than if there is an oil residue in these areas.

That's pretty much it. As I mentioned before I'm not really sure if there is any need to do this, but I'm a bit anal retentive about things like this. It is really no different than setting up the table for the first time for those who did that themselves. I would also suggest not listening immediately after putting things back together. As Thom has told us, it does take several hours for the oil to relax and the bearing to fully seat. I did listen after letting the table sit overnight but things sounded really, really thin. I started up the motor and left the platter spinning for another 24 hours. Now it sounds more like the Gavia I know and love.

[palasr]

Dan,

You read my mind on this - in fact, I started an oil change thread at the end of last week, and decided against posting it, feeling that I was being premature in my desire to fiddle around.

With most turntables, you perform a bearing cleaning/oil change every two or three years as a matter of routine maintenance. I figured that since I have never touched the bearing since assembling the deck a bit over two years ago, perhaps it would be a good idea to do this.

So bottom line it --- For all the trouble and effort, was it worth it sonically??

Cheers,

-Richard

[Salectric]

I went through a similar exercise a couple years ago. I had used the table for about two years at that point and really had no idea what I'd find suspended in the oil. I found nothing whatsoever. The oil seemed as pure as when I had first set up the table. I didn't notice any gunk on the inside surface as Dan described nor any sign of wear except the little dimple in the Delrin. I don't know what this means as far as routine maintenance after the initial breakin. Perhaps something more on the order of 3 to 5 years for an oil change?

By the way, I also noticed that the sound was thin and lightweight when I first reassembled the table. I just left it spinning overnight and everything was back to normal the next day.

Dave

[Dan_ed]

Probably not, Richard. It doesn't hurt, but having to wait for things to settle back to normal is a PITA. I'll know more about the possible sonic downside by this weekend.

Dave, that is pretty much what I heard immediately after setting things back up. It almost sounded like a old transistor radio compared to my ceedee player. I'm exaggerating, of course. But that was the thought that immediately came to mind. It is sounding much better now.

[galibier_numero_un]

I've often wondered what occurs during oil break-in. Does the viscosity thin out?

It raises the question of finding even thinner oil to use.

As I write this, I thought of a means of measuring viscosity. It wouldn't give you a standard number, but would tell you whether the oil is thinning out. Basically, you'd measure the time it took a certain volume of oil to pass through an orfice. Perhaps something so simple as a pipette would work. Of course, you'd need to keep the temperature constant. Thinkin' out loud here ...

Cheers,
Thom

[Dan_ed]

It has been two weeks now. I do think the noise floor of my analog source has dropped. Pretty much every component and cable was moved so it is hard to say for sure what may have caused this. However, maybe there is something to changing out the bearing oil. Especially after that first breakin period. Again, it's pretty hard to say exactly what lead to this. It sure seems to me that surface noises are much lower on a few records I know very well.

[berndt]

http://en.wikipedia.org/wiki/Viscometer