Head rails should just be clean. And by that I don't mean simply not covered with layers of dust. Clean. Sometimes it requires removing the shafts and cleaning them, as well as the brass inserts in the head assembly, with IPA or some other degreaser that just evaporates.

Same goes for the motors, unless you need to unseize them. That being said light oil that penetrates inside the motor will at least not attract all the dust to it. But don't flood the motors, a drop is enough if required (again, unless it's properly stuck and requires extra attention).

Things that require lubrication for long-term operation: worm screws, if your head uses one for postioning. Sometimes small amount of grease is applied to rubbing metal parts. But both of these cases are more applicable to 3.5" drives than 5.25" ones. If you lubricate the drive it might seem to work better or quieter for some time, sure, but after the oil/grease attracts dust you'll have more problems, and possibly also faster wear on some parts. Only once I had to put any sort of lubricant on the head rails and it was precisely because somebody did that many times earlier and the drive saw a lot of usage. This caused the hardened polished surfaces to wear in some places (as well as the bushings) and tend to stick when dry. So rather than replace the parts I've opted to keep lubricating it.

I have applied lithium grease to the rail of the head movement motor. I have also put a little CRC 226 on the rotating shaft of the motor coupling that turns the disk. Does this seem ok to you? How much grease should be applied to the rail? What are the drawbacks? Thank you very much.

Linear bearings / rails are prone to having any lubricants applied react with the iron, forming "gunk" that is sticky, not at all lubricating, and which attracts and holds dust/dirt.
(iron, and salts of iron, catalyze the "drying" reaction of many oils. Not all oils are drying; most are only semi-drying, but that's bad enough. A commonly used oil is sadly, soybean oil. I wish I was kidding; it's what you'll find is inside say, oil meant to lubricate paper shredders. Soybean oil DOES semi-dry, and turns into said GUNK. Presence of iron catalyzes this reaction. Cheapskates that fail at chemistry selling stuff they shouldnt, for use in ways they shouldnt, because it's cheap, and nontoxic. To avoid being bamboozled this way, stay away from liquid oils for these surfaces entirely.)

If you DO apply a lubricant, consider using a dry teflon lubricant there, that wont react with the iron or steel of the linear bearing shaft. Such lubricants use a liquid carrier for application, but leave a very thin dry lubricating film. Avoid using conductive dry lubricants, like graphite.

For worm-gears, use white lithium grease. A little dab will do.

Is there anything wrong with using CRC 226 lubricant on the axle? Is the lithium grease on the rails correct? Regards

Lithium grease on the worm-gear, if it has one.

As others pointed out, most 5.25" drives DO NOT.

What happens when "gunk" forms on the linear bearing, is that it eventually causes a rough spalling type surface to appear on them, due to intermittant/improper rolling of the ball bearings in the linear bearing's counterpart, which is part of the head assembly, along with actual dust and dirt being mechanically erosive there as well.

Looks like this.

(Sorry for tiny image. Had to pull it out of google's cache, since my workplace stupidly blackholes anything not inside the USA, and tech sites are a GLOBAL thing, with many in europe.)

This is very bad juju.

If you positively MUST lubricate the linear bearing, consider a very thin application of teflon dry lube liquid. It dries in no-time, and leaves a thin coating less than a micron thick, that is chemically inert.
(example product.)
https://www.walmart.com/ip/DuPont-Non-Stick-D … Bottle/49235098

LESS than a single drop to the whole rail. VERY sparingly.

To better understand what is going on, it helps to know what is inside the other side of the assembly. While some more simplistic designs are just a brass sleeve bushing, more sophisticated ones actually have little bitty steel ball bearings, like this.

In the case of a simple bronze one (often for very small bearings of this type), there are no balls, but the tolerances for clearance is basically 0. Any dust in there basically becomes sandpaper, and a "wet" surface attracts/grabs and holds, dust/dirt, basically turning it into gritty sand paper, which then erodes the bearing.

In the case of a ball-bearing type linear bearing surface, if the balls dont "roll" (because friction is too low), then the contact becomes shearing instead of rolling, and it slowly erodes the linear rod.

These reasons are why it is suggested to NOT lubricate these.

Finally, I lubricated the rail with silicone lubricant, and the gear of the motor to move the head, with lithium grease. What do you think? The disk drive runs very smoothly. I also greased the rotating axis with CRC 226, and other moving parts with lithium grease as well.

There's a case to be had for dry lubricants like graphite powder, PTFE or molybdenum disulfide. Those will not attract dust and form "gunk"

stamasd wrote on 2024-09-27, 19:07:

There's a case to be had for dry lubricants like graphite powder, PTFE or molybdenum disulfide. Those will not attract dust and form "gunk"

The other two are likely to be ok but Graphite is conductive so you would have to be very careful using that near any electronic parts.

Agree Trashbytes, is like using silver based thermal paste, one must be very careful in useage because it can conduct.
I disagree with some others: do use white Lithium based grease in floppy drives on all metal contact/movable parts.
Better to lube than not lube, is not like we are going to run 1000's disks through some antique old drive. Just keep it off plastics.
We also know being vintage to check our parts once in a while (do you check the oil level in your old car/truck ??? 🤣 )
And IPO on a Q-Tip can easily dissolve and clean the old gunk...

Hi and thank you very much for your help. So, is it wrong that I put lithium grease and silicone lubricant on the moving parts? Should I clean it again and put PTFE lubricant on it for example? Regards

No, you are fine. Just remember that like anything else that is old, check it once in a while. How often do you check the cpu or PSU fan for dust build up and blow it out ? Do same on these old floppy drives. Is not rocket science though some try to make it so...