Gear oil replacement?

I noticed that the cassette door on my TRC-920 is very fast when it starts to open but quickly slows to molasses. I figured the gear oil thickened up over the years but then I ran across this post on another forum saying it was god-awful slow when he bought it new in '83 and even earned his box a nickname because of it.
I'm wondering if molasses doors could be refreshed with something like an OTC grease.

Interesting. I had a deck door (I can't now remember which box it was) with 'lubricant' of some unknown description on the door plastic cogs that had solidified to an almost solid mass, akin to toffee, resulting in the door being unable to move freely. I applied a couple of drops of Servisol Super 10 and rubbed the gunk with a cotton bud/Q Tip and this thinned out the gunk enough to remove it. However, by working the deck door backwards & forwards I noticed that the gunk had thinned out enough and mixed with the Servisol Super 10 to a point whereby the door moved as freely as it was intended to do so. As the problem was now solved and the cogs were lubricated adequately I left it like that only checking after a couple of weeks to find all was still good.

Ooh that's interesting. I might have to try that, I've got one that's pretty dry. Perhaps over time the material "cakes" and just needs to be stirred. I might have to try that. I am uncertain what it's composed of, but it's not exactly grease.

On some boomboxes such as Sanyo's, they used a grease material that is not friendly to rubber. When replacing them, it's advisable to use non-petroleum based products for better plastic/rubber compatibility such as silicone based grease.

As for viscosity, lets just say that I've found that that lower viscosity products are easier to find than ultra high viscosity products. If you don't like how that door ejects, then just replace with a lower (slightly) viscosity product. Obviously, an extremely slow eject makes it more likely that someone will get impatient and try to "help" it along, which might could break something if done enough?

Kind of an interesting topic I've always been curious about. The how and why some open slow/fast, what's it supposed to be, and how do I get it there.

Personally speaking, even slower opening doors are preferable to the doors that jump out with nasty bit of the ol' aggression combined with a sense of urgency. A small pad of rubberised foam usually sorts this out.

trippy1313 said:

Kind of an interesting topic I've always been curious about. The how and why some open slow/fast, what's it supposed to be, and how do I get it there.

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Yes! Interesting topic!

I think two types of damping was used. One was just a friction wheel with a viscous grease and another with a damping piston cylinder arrangement.

They used air damping piston/cylinder arrangement for this mechanism in some high end decks and boxes. The piston had a rubber sleeve. The mechanism became slow only when the rubber degraded over the years. Once the rubber sleeve went bad, it was hard to find one to replace it. The tip of small syringe piston came to my rescue once. In some boxes it still look like new.

Silicon oil is the best for this application,and silicon grease to have more control on the damping. After cleaning the cylinder walls, apply a drop of silicone oil on the rubber.

Oh yeah! I noticed my Hitachi has an air piston, it works great, I haven't seen one of those before. I could see that going bad but oddly enough the sleeve is still good after almost 40 years.

Norm, do you know if belts just turn to goo on their own or is it always from interactions with oils/greases? It would make sense with all the lubrication on decks. Every time I get grease or oil on something rubber, it almost inevitably starts to disintegrate.