Motor mystery

[Joetrain59]

I bought a LL FA/FB-1 set, the early 2000's release, whose B unit was always a bit balky at working. I wrote on the jewel case, "not running well", and put it away for years.
 The other night I went at it, tore it down, cleaned all pick-ups, frame tabs where motor contacts fit. Wiped the windows, checked the oil, dollar gas!
 So last night, I says to meself, you haven't checked the motor out. Spun freely, by hand. I decided to check commutator. I pulled off a brush cap, things looked great.
 Put loco back together, still balked. Had to press on frame sometimes to get it to run, then it would stall here and there and test track. Disassembled it all, decided to check other         brush. Discovered there was no spring in cap to make brush firmly sit on commutator! Yes, I opened that brush cap very carefully, so as not to have spring fly away.
 I assume that would be a problem? Now to find another spring. Your thoughts?
 Thanks,
 Joe D

[peteski]

 I assume that would be a problem? Now to find another spring. Your thoughts?
 Thanks,
 Joe D

Yes, that is a problem.  I believe that either Kato or Atlas sells replacement brush sets, and they come with springs.  Or someone here (like me or other "motor-heads"), has some spares.  I'll look for them in the next few days.

[Joetrain59]

Pete, the spring looks similar to some used with factory installed couplers I've seen. I have some older Atlas motors that I can check for fit, too.
 Thanks,
 Joe D

[mmagliaro]

There are lots and lots of Kadee HO scale phosphor bronze coupler spring sizes, and one of those would probably work.  The trick is getting the correct size.  If you are able to measure the length and diameter of the other brush spring, I could go through my spring stash and see if I have one that matches.  (I have accumulated many of the Kadee coupler spring packages over the years for just these types of problems).

[Joetrain59]

Thanks Max. I also save all those little "flat" springs that come with a lot of locos these days, in that little plastic bag.
 Some came in handy last week.
 I have a digital caliper, but let me see what I have here.
 Just weird that this motor was assembled this way.
 Joe D

[Doug G.]

It probably wasn't assembled in the spring time.

Doug

[u18b]

Be sure and choose a spring that is similar in size.

If the spring is too strong for that application, it may wear down the brush prematurely.

[Joetrain59]

I used a brush spring from an old Atlas "fast" motor, a perfect match. (From a RS series ALCo loco.) Motor ran fine.
 I also found a LL FA motor in my stash! Put that motor in loco, too, just for sh*t^ and giggles. Ran just like the original
 motor. But I still have that wuh-wuh-wuh noise to it. Did pull the inner bearing blocks a few days ago, did not help that
 much. Put some white teflon grease on the worm, it was more quiet, but still that noise. Well, ALCo's made plenty of noise,
 do I live with it? I'm out of ideas.
 Thanks,
 Joe D

[Steveruger45]

But I still have that wuh-wuh-wuh noise to it. Did pull the inner bearing blocks a few days ago, did not help that
 much. Put some white teflon grease on the worm, it was more quiet, but still that noise. Well, ALCo's made plenty of noise,
 do I live with it? I'm out of ideas.
 Thanks,
 Joe D

From your description it sounds like a once per revolution sort of noise.
Have you checked The gears in the truck towers and wheel gauge ?
Make sure the gears here are not rubbing on the tower/frame.

[Joetrain59]

Thanks Steve. I did check wheel gauge, they were spot on.
 But I will look at the truck gears. Never thought of that.
   Joe D

[Doug G.]

That kind of noise usually has to do with worm/worm gear mesh. Usually too tight/close a mesh.

Doug

[mmagliaro]

Related to Peteski's comment... is the "wuh wuh wuh" noise once every time the worm goes around, or once every time the wheels go around?  The answer is critical to diagnosing this.

If you notice that the sound is once per WORM revolution, try shimming the motor up in the air with a .003" brass shim... K&S sells packages of really thin brass sheet in an assortment pack that has .001, .002, .003 and .005" in it.  .005" is probably to much.
Try .003"  You might just have a tight spot in the worm mesh.

[Joetrain59]

Well, I looked at gears on trucks, and the "middle"set of gears were right up against the truck frame. They seem to float on their axle. I used a small blade screwdriver to nudge them away. I'll be a suck egg mule! Loco is running much more quiet now. I'll see if the gears stay put.
 Thanks, learned something again here.
 Joe D

[Steveruger45]

Well, I looked at gears on trucks, and the "middle"set of gears were right up against the truck frame. They seem to float on their axle. I used a small blade screwdriver to nudge them away. I'll be a suck egg mule! Loco is running much more quiet now. I'll see if the gears stay put.
 Thanks, learned something again here.
 Joe D

Glad that helped.  You might have to renew the truck towers and the gear sets in them, but before you do there is one last trick to do if these gears go back as before and that’s reverse the trucks to try and put some of the forces working the opposite way.   It’s not a cure all but often works.

[Joetrain59]

Tonight , I shimmed the motor with a strip of.025" phosphor bronze. Loco runs very quiet now.
 Those middle gears I mentioned actually have a "spacer" as part of them.
 Thanks again Max!
 Joe D