800k drives...finicky!

[LaPorta]

Hi guys,

ive torn down a few 800ks, and I seem to have some mixed results with the lubrication process. I’m using white lithium grease, and not only relibricaring the chassis/carriage, but also the eject motor gears. The auto eject on them seems sluggish. Do these eject motors slowly become crummy over time, or am I doing something wrong stopping them from making that nice, easy eject? Also, auto inject usually doesn’t seem the same as it always was and is a little sluggish. Is the lithium grease too heavy? By the same token, is it still a huge mystery as to what the heck the factory used? Where am I going wrong?

 

[Johnnya101]

You could try removing most all of the grease and see how well it ejects then.

Are you sure the gears were lubed? I don't think I remember seeing any when I opened mine up a while back .. Or maybe it's a small amount that I didn't notice.

 

[jgk]

Last time I did this (which admittedly was quite a few years ago), I used a clear silicone based grease, primarily because I felt lithium was going to be too heavy. And at that, I used it very sparingly. As for the inject mechanism, mine was failing to inject, as a spring had snapped. Once replaced, it was functioning good as new. I'd check yours to be sure they've not stretched over the years. 

 

[LaPorta]

I got the inject to work by removing the grease that I had put on the internal sliders...which it appears aren't supposed to have any. That's fine. I tore apart the entire eject motor, found somewhat gunked oil in there, cleaned it all, and used fine instrument oil to relubricate sparingly...and still there is an eject slowness. Perhaps there is too much grease somewhere...but where? I suppose pictures might help. Does anyone have a video of theirs at work for compare?

 

[LaPorta]

Looking more into it, this stuff looks like it could be a good substitute. It appears to be quite thin, used for cold applications so as not to gum up.

https://www.amazon.com/Corning-Molykote-Light-Grease-Lubricant-x/dp/B0141NIS8M/ref=sr_1_1?ie=UTF8&qid=1547420610&sr=8-1&keywords=light+grease

 

[jgk]

Dug up some of the pics that I took when I did mine (over 13 years ago!). Have you completely disassembled and cleaned the entire eject assembly (pictured)? As I recall, the grease there on mine was pretty gunked up. If that's all moving freely, and you can manually actuate the assembly to easily pop a disk, then I would think it points to your eject motor, or the signal driving it.

 

[LaPorta]

That's a 400k...but I see what you are saying.

It is very difficult to fully rip an 800k apart, but I did get all the stuff off. It does eject, it just sounds like the motor strains. I can also manually eject. I think it's probably the weight of the grease. No one seems to know what was originally used.

 

[LaPorta]

So I took off the lithium grease and substituted Molykote 33 grease...inject works like a charm, eject still "sounds" weak...but it sounded like that before I started working on it. Is there any way these electric motors can get weak over time?

 

[Blake]

Have you tried realigning the gears and replaceing the small plastic gear, that usualy causes the thing from ejecting correctly.

 

[LaPorta]

I did order a replacement gear set for the one the usually cracks. The teeth of the others seem to be in good repair.

 

[LaPorta]

View attachment F48639D0-2EC0-4A19-B428-12646C184EAC.MOV

 

[jgk]

Looks quite normal to me. The internal drives on all the older Macs I've ever used behaved just like yours does. They always had that "strained" sound, even back in the 80's.

 

[Crutch]

That sounds slightly less strained than the 800k ejects on most of my Pluses. I’m with you though, that energetic eject on the external 3.5 drive is much more satisfying...