Collins 390 gear lubrication

[iw5ci]

I found that the mhz control is stiffer that one year ago.. maybe becausa i seldomly use it...
which kind of oil i can use to lubricate the geartrain? is a light sewing machine oil good for the purpose or is better wd-40?

[kb3ouk]

i think the sewing machine oil would work, or some kind of spray  lubricant. WD-40 is not exactly a lubricant, it is  a water displacing spray, but it could work for what you need.

[WA3VJB]

One of the restoration experts, Chuck Rippel, has advised great caution in lubricating the gearset in both the R390A and the older R390.

If you insist on using something, it should be a synthetic lube rather than anything petroleum based. The reason is that the petroleum-based stuff will evaporate, especially with heat, leaving gunk and varnish that will make the gear set stiff.  

This may have been what happened as you notice the rise in your Megacycle tuning stiffness.  A version of that happens at the Kilocycle tuning too, but there's less to wank.

[kb3ouk]

i think its silicon spray that i used on one of my rigs, i forgot about that, that would be better.

[W7TFO]

I've had good luck with the slightest amount of synthetic 90-W gear lube, applied via small paintbrush.  It really stays in place.

73DG

[KA3EKH]

Specialized synthetic R-390 lube? Wow, isn't that what they had on the fancy chrome plated R-390? I worked on a lot of this stuff including more modern gear and items with mechanical drive trains that make the R-390 look simple. My ARC-38 has gears, cams, transmissions and things that I have no idea what they are and three in one oil has always worked for me. Also used it on very expensive video tape recorders when television stations use to use them with no issues, the key was always to use the smallest amount necessary for the job and not to go crazy with spray lubricants that coat everything. A small drop of oil goes a long way. I often like to use WD-40 on stuck items like frozen control shafts but will always use the red tube, spray the stuff into the trash can and then just use the last drop off the end of the tube to apply to the surface of the stuck joint unless I am working on the car or jeep, then I just paint the offending part with it!
Ray F

[W7TFO]

Nah, I mean use syn 90-weight gear lube for cars.  Sticks.  Won't evaporate.

73DG

[WB6NVH]

I have been using synthetic Dexron compatible automatic transmission fluid for awhile, it's thinner than the 90W although I am not sure whether that is important.  Both stay put and don't evaporate.

This will be way better than they were in original service.  I can remember some real "cement mixer" examples in the Vietnam era.

[flintstone mop]

i think its silicon spray that i used on one of my rigs, i forgot about that, that would be better.

Shelby has a good thought. I use silicone sparingly on the cams and any 'bearing' surfaces. I do not put any lubricant on the gears. I have all of the covers installed and there is no dust collecting inside my 390A. I have noticed a stiffness if the radio is off a few days during the Winter and the room is 65 degrees F. The radio might be off more during the Summer months to hide from MaNature. Basically it is mostly on 24/7.
Any lube on the gears and the covers off would bring more maintenance problems, I think
Fred

[DMOD]

Nah, I mean use syn 90-weight gear lube for cars.

A cautionary thingy here. The chemistry of gear lubes is such that they contain high levels of phosphorous and sulfur additives which is bad for copper or copper plated surfaces.

Try lubricating the bearings with Ford Type "F" atf and use sparingly.

Phil - AC0OB

[W7TFO]

Nah, I mean use syn 90-weight gear lube for cars.

A cautionary thingy here. The chemistry of gear lubes is such that they contain high levels of phosphorous and sulfur additives which is bad for copper or copper plated surfaces.

True enough for GL-5 type petro-sourced lubes. 

I've been told by my oil guru that the new syn lubes have no sulfur or such copper-eating things in them, as those high-pressure additives were not necessary in the formula.

Others may weigh in on this...

73DG

[W2VW]

It still smells nasty.

[DMOD]

I've been told by my oil guru that the new syn lubes have no sulfur or such copper-eating things in them, as those high-pressure additives were not necessary in the formula.

Current GL-5 synthetic gear lubes contain 900 ppm of phosphorous and 3,500 ppm of sulfur. Phosphorous and sulfur are the extreme pressure additives. I think your guru is misinformed.

[WA1KBQ]

Personal favorite lubricants are all over the map here and may or may not work; some may even have adverse affects. We need a mechanical engineering recommendation.

[flintstone mop]

Personal favorite lubricants are all over the map here and may or may not work; some may even have adverse affects. We need a mechanical engineering recommendation.

Definitely good advice. I cannot find anything in the 390A manual about maintenance and lubrication of the mechanical. Collins knew, I'm sure, what type of service these receivers would have in a tactical situation or comm center. I would still hang on to my original post of using a clock oil lube or silicone on the cams and attempt to get something in bearings. Nothing on the gears.

[WBear2GCR]

The hobby industry sells a wide variety of viscosity synthetic oils, from fairly thin to amazingly thick and slow - small containers (4oz.?) are commonly found in better hobby shops... I have used it for all sorts of damping and lube work... doubt it contains any sulfur or phosphorous additives...

                            _-_-bear

[AA4HA]

Easy answer, Mobil 1 synthetic automotive oil. One quart bottle will last you forever.