[R-390] Gear Cleaning OMG!!!!!!

[chuck.rippel at cox.net]

I read the gear cleaning procedure quoted below and found it very 
troubling.  Wanna clean the gear train, here's how:



Carburator cleaner has its place in the process when used properly and 
safely.  Buy a 1 gal pail of GUNK carburator cleaner.  There will be a 
small parts basket in the can.

1- Tear down the RF deck, remove all the gears.

2- Separate the stainless steel from the brass gears.

3- Put the stainless steel gears in the parts basket and put the basket 
in the carburator cleaner over night.  Orient the handle on the parts 
basket so you can get to it without putting you hand into the chemical. 
Put the lid back on the can.

4- Several times during the soak, remove the lid, grab the handle and 
move the basket up and down so that the parts cleaner can wash the gears 
and get in between the rotation stops on the KC Change and MC Change 
shafts.

5- After the soak, remove the parts basket, take it over to your out 
door hose and begin rinsing the parts in the basket.

6- When the water runs clear from the basket (its milky white when 
mixing with carburator cleaner) put a couple drops of Dawn dishwashing 
detergent in the basket, rinse again letting the soap foam up around the 
gears.  Continue to rinse until the soap foam is gone.

7- Let the gears drain a bit in the basket.  While you are waiting, warm 
up you oven to 250 degrees and let it sit there for 30 minutes of so.

8- Put the basket of gears into the oven, close the door and shut the 
oven off.  Let them sit in the oven 8-12 hours.  The object is to drive 
any moisture from between the split gears.

9- Repeat with the brass gears BUT, only soak them 4 hours.  The 
chemical MAY/will probably discolor the brass.

10- Perform steps 4 through 8 but modify the oven temperature much 
lower.  Say... 150 degrees (no split gears here)  Too hot and the brass 
WILL change color.

11- Lubricate the split gears (between the mating surfaces) with 70W 
synthetic gear oil.

12- Re-assemble, set the split gear spring tension, correctly time, and 
set the over-run on the gear train (If you cannot do this, do not 
proceed from step #1)


Not to step on anyones toes but.....   please do not do the below ! 
There are so many reasons to alter this procedure, I'm not going to list 
them.  Soak the gears in carb cleaner while they are still mounted on 
the radio and not able to be properly rinsed will net you a radio that 
will smell so bad, you'll be running it in your garage for a year. 
Especially when it gets hot.  There will be carburator cleaner in 
between the faces of the split gears.  Even synthetic oil will break 
down when it comes into contact with carb cleaner.  Carburator cleaner 
will eventually pit the brass gears; it HAS to be rinsed off !

WD-40 is not a lubricant, it was actually developed to be a Water 
Displacement..... "W - D" Fourty....  Its an ok cleaner.  After cleaning 
up a main chassis, I'll put some WD 40 on a rag and wipe down the whole 
thing.  Drives any water out and cleans up any last bits of krud.

Cleaning up the gear set = re-timing the rig.  That process makes up 80% 
of making your R390A play to its potential.  The timing can't be 
"close," "Ok for government work," "just a bit off," etc...   If its not 
right, the radio will not perform to its potential.

With the above sermon, I can understand and appreciate trying to clean 
one up without having to go through the timing trials.

Unfortunately, "there ain't no short cuts" that work.   I've tried 'em 
and am still looking.


Chuck Rippel



>>
>>> Bob,
>>>
>>> I found the following method best to clear the gear train without
>>> disassembly. I've completed two R-390a's with the following method.
>>>
>>> 1. Remove the RF deck from the receiver.
>>> 2. Take it outside and hang just the gear portion of the RF deck off 
>>> a
>>> table or other suitable object.
>>> 3. Use a FULL large can of WD-40 to spray all the gears until most 
>>> of the
>>> grease and gunk is removed. WD-40 is mostly Stoddard solvent. Keep 
>>> WD-40
>>> off painted surfaces as it will remove some paints/stamps.
>>> 4. I then use a full can of carburetor cleaner including scrubbing 
>>> with a
>>> brush or rag to clean stubborn spots.
>>> 5. Relubricate with Mobil One synthetic oil. Use a long spout oiler 
>>> to
>>> reach inside the gear train.
>>>
>>> I've previously posted pictures to this group but will send you a 
>>> picture
>>> if you'd like to see the results.
>>>
>>> It's not difficult and takes less than an hour. The gears turn 
>>> smoothly
>>> after this process.
>>>