Tech Tip: IJ POA gearbox
Cliffy
I mean, so... :)
Whilst (whilst?) *reconditioning* - I learned that one from Jack G.
today- an IJ for a friend I had all the problems everyone else has with
the path of adventure. I figured while I had it all torn down I may as
well have a look at the gearbox, especially since it seemed to rotate
freely one way but would bind to a stop the other way. This tip is for
Revell modelers skill level 3. Not too advanced but you need to be good
with power tools :)
You need to remove the POA and the opto trigger arm from the gearbox
shaft. You'll need to unplug the motor and opto board from the bottom.
Next, remove the motor from the back, it's only 2 screws. Now you can
remove the gearbox and it's bracket from the front of the backboard.
Remove the 4 screws holding the gearbox to the bracket and opto board
and it's bracket.
You should now have a bare gearbox. You'll see it is held together with
4 long rivets. Use a power drill with a 3/16" bit and drill out the
rivet mushrooms on the back. Now support the gearbox over something
solid and tap out the rivets with a 1/16" to 3/32" pin punch. They will
be tight but you shouldn't have to pound on them very hard at all. Once
removed you can easily separate the two halves but be careful not to let
the gears fall out. They can only go in one way but there is a spacer or
two in there and you don't want to lose them or have to figure out where
they go.
Now you can remove the gears and spacers one at a time to clean them.
Why remove the old green grease? Well, because it will be contaminated
with years of tiny metal particles, that's why. When I removed mine I
expected to find worn gear teeth or even missing teeth causing the
binding. Such was not the case. The binding was due to ZERO lubrication
in the case bushings! After all gears and case halves are clean you can
re-lubricate everything. Start by using Teflon grease. Scot Bogart
carries Super Lube with Teflon on his site at http://www.pinrestore.com
and it's what I use. Use your fingertip to push some into the blind
bushings in the case halves and pin axle holes. Don't stuff the blind
bushings completely, just about half full is enough and will let the air
escape when you reassemble. Smear some lube around the teeth and bearing
surface of each gear and reassemble. Make sure you get some lube on the
spacers too and and bearing thrust faces. Do NOT overfill the case. In
fact the grease on the gears themselves is more than enough.
Carefully snap the case halves back together being careful for the small
transfer gears pin axles. If they don't snap together easily then one of
those little axles isn't lining up properly. Ok, now you can push the
rivets back in. They will not hold it together but will help in
alignment. No need for new rivets since the 4 screws that hold the
gearbox to the bracket also hold the case together! Lucky us! :)
You should now be able to twist the output shaft with your fingers and
it should move smoothly in both directions without binding. If it does
still bind then the gearbox bushings or axle holes are too far worn and
it will need to be replaced.
Hope this is useful to someone!
--
Cliffy - CARGPB2
A passion for pinball!
http://www.passionforpinball.com
beaver
Edward Cheung CARGPB26
> carries Super Lube with Teflon on his site athttp://www.pinrestore.com
Cliffy
beaver wrote:
> Nice job Cliffy. I hope I won't have to do this any time soon.
>
> Edward Cheung CARGPB26
>
> On Feb 11, 5:48 pm, Cliffy <crin...@comcast.net> wrote:
>> Sorry for the abbreviations but if you have an IJ you already know what
>> I mean, so... :)
martin
One more tip - take photos of the gearbox as you disassemble it so
that you can get all the small parts. Helps to have assistance, as
your hands will be filthy!
marc_b
motor years ago. It typically screams like a banshee! Took it apart
and repacked it with grease. Was going to do it again with my new
motor- but your White Lithium grease is a much better idea for a
lubricant. I'll give that a try on my WCS.
marc b