[R-390] R-390 (Non-A) RF Gears Cleaning

[Jim Whartenby]

RossGreat!  Someone who is familiar with both R-390s and clocks!From what I have read concerning lubrication of clockworks, one does not lube gears, only pivot points.IIRC, the R-390/URR manual says that it is better to not lube then to over lube.Comments?Regards,Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy 

    On Friday, February 13, 2026 at 11:23:48 PM CST, ROSS HOCHSTRASSER <bavarianradio at comcast.net> wrote:   

 Hi all, My approach may be be a bit different as I have been in the clock repair business for over 40 years. I did this R-390 restoration over ten years ago.  when I see gears, I was taught to disassemble everything that can be disassembled and CLEAN it. I have  lots of pictures that I can send to anyone who wants to see them. Here are two showing the level of disassembly I was able to achieve.  The results are pretty and pretty successful mechanically.  As someone has already mentioned, WD-40 is NOT a lubricant, although  it can be useful de-gunking things before disassembly as long as it can be completely rinsed out. I use a heated ultrasonic cleaner  with an ammoniated solution, water rinse and heat drying. If there is any interest, I can be contacted via email  here or directly , my email address is good on QRZ  73 W1EKG
> On 02/12/2026 2:27 PM EST Jim Whartenby via R-390 <r-390 at mailman.qth.net> wrote:
> 
>  
> All of these comments seem to be about what works best for the individual who is responding.  It is all opinion based of which one is as valid as another.  I bought the WD-40 in a gallon container.  At the time, this was the cheapest all purpose solvent at Lowes some 15 years ago.  I still have half of that gallon remaining after cleaning three R-390A receiver gear trains.
> 
> I checked the gallon Naphtha back panel, it says to not use it as a general purpose cleaner.  As mentioned already, brake cleaner is quite harsh.  I am sure that none of these products are healthy but it seems that WD-40 is the most versatile.  Perhaps WD-40 does not do all things very well but it seems to be good enough for my purposes.  It along with a detergent gets the job done.
> 
> Enclosed is an analysis of what is in WD-40.  It seems to be mostly white spirits #1 aka mineral spirits #1 with other additives to act as light lubricants such as mineral oil.  Since I use several solvents in my cleaning process, I don't feel that I am leaving any one as a residue that may harm the geartrain.  The smell does not bother me as I use it only when I'm outside.  I am pleased with the results as I am sure that the other solvents already mentioned work as well for those who mentioned them.
> Regards,
> Jim
> Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy 
> 
>    On Wednesday, February 11, 2026 at 08:44:22 PM CST, Spence Barton via R-390 <r-390 at mailman.qth.net> wrote:  
> 
>  I totally agree with this. First I can't stand the smell of WD-40. Some 
> say it's got kerosene in it and some other stuff. Kerosene isn't my 
> first choice for a cleaning solvent anyway. I definitely don't need or 
> want the other stuff in it. Naphtha (white gas) is fabulous. It's a 
> great solvent for grease. Won't affect most paints or decals. Cleans up 
> great. Doesn't cost much.
> 
> On 2/11/2026 2:43 PM, Barry wrote:
> > I'm not a fan of WD-40 for cleaning.  It really wasn't it's purpose.  I like naphtha for a grease and oil cleaner followed by synthetic oil judiciously where needed.
> >
> > Barry - N4BUQ
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