Atlas GP20? Vaporidium?

[u18b]

Been running mine for about a week now and no motor tab problems yet, so I opened up the chassis and poked them to see if they exhibited any brittleness. And they didn't, so I guess that particular issue has been resolved.

But back to my noisy drivetrain, check this out - each worm only has a single bearing block holding it in place (despite the fact that the chassis has mounts for four). I wonder what noted locomotive guru Rob Bearden @u18b would have to say about that? I'm no guru, but it seems like it's just asking for trouble....



Also, I'm thoroughly unimpressed with the sound and I wonder if the problem may be that the speaker cavity in the chassis is not as airtight as it should be. I mean, what's the story on the pointless openings in the sides of the cavity that don't line up with the equally pointless ribs inside the fuel tank?



-Mark

I just saw this.
I think it is GREAT---- however....

If you are getting noise, the most likely culprit is the positioning of the hex nut.

When two bearings are used, the hex nut only needs to engage the hole- that's it, no big deal.    The two bearing do the job of restricting the lateral movement of the worms.

However, when you remove the inner bearing, the entire worm can rattle by moving into and out of the flywheel.
I always fine tune the hex nut so that there is only a a LITTLE play in a worm when I am finished Beardenizing.

Do a test right now a use a little screw driver and see how much you can wiggle the worm.    If it is a lot- then you are hearing it rattle.

If it doesn't move at all, then the hex nut is too deep into the flywheel and is causing a bind- which can also make noise.

You are looking for a Goldilocks spot that is just right.

[u18b]

Oh.
And Mark   @spookshow  , on the other frame half that does not have the bearings.....
Make sure the the fingers of the little brass plate are not compressed and are actually pressing on the bearing.

I've see the finger compressed and thus the whole bearing rattles.

[spookshow]

Ron, the worms are free to slide back and forth about a millimeter or so. And if I understand your comments re the "fingers", they don't appear to be compressed -



If that's all OK, where is the noise coming from?

Thanks,
-Mark

[spookshow]

I put some lube on the bearing blocks and gave the fingers more of a bend and that does seemed to have helped a little. But at full throttle it's still considerably louder than, say, a Life-Like E7.

I wonder if those weirdo new wiper strips might be causing trouble? Didn't there used to be a problem with the old Life-Like SW9/1200 where if the wipers weren't bent "just so" it would cause noise problems?

-Mark

[u18b]

About a 1mm wiggle is good.

And yeah.... the "fingers" are correct.   The inner one is not used and so can be compressed.   You bent the outer one a bit outward.. and that's good.

As to the SW1200..... I don't recall anything about the pickups on the side.

However, the first run used plastic worms which were not perfectly concentric.   Replacing them with brass helped.

[spookshow]

OK, so if there's nothing that's in obvious need of tweaking I guess it's just never going to be Kato quiet. Not the end of the world as it's not hugely noisy on the lower half of the throttle. But the drivetrain noise certainly does drown out the barely audible speaker, and I don't know what the answer is there. Maybe this is why only a couple of stores are selling these things....

-Mark

[peteski]

What about the (hex?) coupling on the end of the worm shaft sitting inside the flywheel (assuming that they still use that coupling method) causing problems?  To me 1mm of fore and aft play in the worm would seem a bit too much.

[Mark5]

That is interesting - I seem to recall that the LL GP20 was Kato quiet.

[spookshow]

What about the (hex?) coupling on the end of the worm shaft sitting inside the flywheel (assuming that they still use that coupling method) causing problems?  To me 1mm of fore and aft play in the worm would seem a bit too much.

Yeah, I dunno. At this point I think I've gone way beyond what I need to be doing as a reviewer, so I think I'm just going to record my complaints and get on with my life. If someone else discovers reasons / fixes for any of this stuff I will happily record it for posterity.

-Mark

[spookshow]

Mine decided it didn't want to run this morning, so I had to adjust the motor contacts to get it going again. And yep, they both broke. What a piece of junk! 

-Mark

[tehachapifan]

This is not good news, especially since I just sprung for one. Guess I'll see what mine is like.

[pmpexpress]

Lombard Hobbies just listed their inventory of Atlas Master Gold Series N 40004522 DCC/ESU LokSound V5 Equipped EMD GP20 Locomotives.

[spookshow]

I foresee a lot of unhappy campers. It's hard to remember the last time I reviewed a new Atlas loco that had this many problems. I guess maybe their ill-fated 2-8-8-2 of '94?

-Mark

[tehachapifan]

The Lifelike version I have of this model, while not DCC friendly at all, runs silky smooth. Hard to imagine how it got so messed up since then, except it doesn't seem to take much to cause binding and/or noise (deep gear mesh between the worm and the top truck gear being a common growling noise source). I was able to completely quiet down the very first run of the VO-1000 (the one with the shiny frame) by basically shimming the underside of the worm blocks and motor. Did something similar with the first run of the Athearn F59PHI, although that had a totally different worm housing assembly I had to modify.

[Sokramiketes]

I wonder if those weirdo new wiper strips might be causing trouble? Didn't there used to be a problem with the old Life-Like SW9/1200 where if the wipers weren't bent "just so" it would cause noise problems?

-Mark

Yeah, I remember this.  If the strips were bent up, and the truck went too far up into the worm, it was noisy.  Part of why you can't hardwire the trucks and remove the pickups since they were part of the suspension.  Atleast that was my understanding at the time. 

The GP-20's used to be Atlas/Kato quality and I still have some from the $20 close out days.