Had six GP20's I scored recently out for a test run and some are noisier than others. One in particular was slower and noisier than the others so I stripped it down, removed the excess lube and checked the gears for burrs, etc., reassembled, and test run again with great improvement. Haing not run these on a layout as yet I can't comment on the noise transmitted through the track but as Pete points out they were quiet enough on my own Uni-Track test track.
Gats, Finally got to run mine this weekend and I saw the same thing with my units. They did get a little queiter as they ran. I will try and strip one of them down this week and give it a look through. Sharp looking thought I tell ya. Here's a picture:
I ordered one way back when the sale was announced and converted it to DCC. Runs great, quiet and slow.....until this weekend. After a week of non-use it started to jerk and lurch all over the layout. At first I thought is was the track but all my other locos were doing fine. Then I thought maybe there's a short as the light was flickering on/off. At the last resort I loosened the frame up and drop both trucks. Low and behold there was a dirt spot on the wipers. Took some rubbing alcohol and cleaned it up. Now runs like a champ, just like when it was new. Last week I received three more for bashing purposes. One sounded really loud and would drop 50% of speed going into a 9-3/4 turn. Not very smooth running either. Instead of wasting time to try to figure out what it is, I just sent it back to LL. I asked for a swap of a new one so I should receive it in a few days as UPS from Baltimore to NJ is next day. (BTW, I web ordered 12 noon on a Tuesday and UPS was ringing my bell on Thursday evening!)
I've converted six to run under Bachmann F-7 shells with DCC. I have good and bad news. I test ran all six on a test track prior to conversion. All were quiet on a Uni-Track loop on top of 1.5 inch MDF. After conversion and moving to my foam board layout, which amplifies running sounds, four of them are relatively quiet; two are grinders, but run at almost identical speeds to the quiet ones. I wondered whether the noisiness was just amplified by the foam board. But I took the two off and disassembled them. I found that, in one, I had misplaced the motor in its plastic cradle. It was perhaps two degrees off on axis. I put it back in place. That did not help the noise. On the second, there was nothing out of place, but I noticed something: the spot where the metal "U" of the motor housing meets the plastic piece that holds the brushes looked odd compared to the five others. My theory is that the metal U is a multi-stage stamped piece and there may be variations in its forming, trimming and later mating to the plastic brush holder. Many years ago, I worked in a GE clock factory. The $1.29 specials could be silent, quiet or noisy. So I'm thinking that the motor in the noisy ones has something a little oversized or misshapened, and thus transfers noise to the frame.
In almost all cases the noise can be eliminated by removing the bearing block on each side of the motor shaft. Ron Beardon gave this advice awhile ago, and I followed his example. I have yet to have any adverse reaction to the missing bearing block and the units are all silky smooth. I had a few that sounded like coffee grinders, and once the inner bearing blocks were removed they became whisper quite. You might want to try this on your worse offenders. I have done this on every GP-20 and Atlas GP-7/9 on my layout.
The Atlas GP7 shell fits pretty good. Are the trucks and fuel tank a good enough match? I really have no idea. Thanks, Loco1999
ok, just wanted to make sure i was clear on it. thanks for the clarification. i'll have to give it a try and see. but it might be a while before i can get back down to the club layout and give it a try though. oh well.... a person must work to pay for house and hobby! thanks guys ( &/or gals), would hate to discriminate!!!
