# Aristo GP40 drive wheel pitting



## eheading (Jan 5, 2008)

I recently purchased an Aristo GP40 that was manufactured 8 months after the original production run. First of all, the new motors run very smoothly and draw significantly less current than the original motors did, so I have elected to keep the stock motorblocks in this engine rather than replace them with FA motorblocks like I did with my first GP40.

I have noticed that the wheels are wearing smoothly just like other motorblocks I have and have had over the years. I don't see any pitting at all of the wheels like I thought I heard about on this forum. As some of you know, I am totally battery powered. Therefore I conclude that the pitting, if it is occurring is due to the current passing from the track, and perhaps arcing against the wheels. Is this the general consensus on the cause of any pitting? I am not trying to start a war between battery power and track power, but rather just trying to understand the mechanism here that might be causing the pitting.

Ed


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## Greg Elmassian (Jan 3, 2008)

Yep, pitting is almost always from current... the problems with the first run was poor plating quality, many people had plating that just flaked off. 

That combined with motors that drew more current, and quite a few defective ones that drew a lot more current, pitting was common. 


2nd run was better. 

Pitting is also different on SS track vs. brass track. See the link below for a detailed explanation and investigation:


*http://www.elmassian.com/trains-mai...estigation* 


Greg


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## eheading (Jan 5, 2008)

Thanks for the interesting and informative link, Greg. I thought I recalled a discussion on here a couple of years ago, but I couldn't locate it.

Ed


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## Greg Elmassian (Jan 3, 2008)

The history is I believe that the GP-40 was the first loco built in the new Sanda Kan factory... this is just before Kader bought Sanda Kan.... 

So, the problems are kind of to be expected... the poor plating, the wires for the mu misrouted, and the problems with the motors. 

Too bad, because all of that seems to be corrected in later runs, but it's hard to tell if you have a 2nd run loco or the updated motors. 

(don't let that stop anyone from buying one, Aristo will send you the new motors free, or replace the motor blocks free, you are just out shipping) 

Regards, Greg


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## eheading (Jan 5, 2008)

Actually, if you can look at an engine before buying it is possible to see if it is a second generation model. The most obvious thing to note is that the mu connectors now do come out their own hole rather than coming out with the coupler. Second, if you turn the engine over and look at the motors, the original motors had an opening where you could actually see a fan on the main shaft. The newer motors you cannot see the fan, and there are just slots in the housing. At least these were differences I noticed between my original model and my later one. I think I might have mentioned too, that the average current draw on my new GP40 appears to be around 1.4 amps, while my oiriginal engine drew an average 2.0 amps.


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## Paul Burch (Jan 2, 2008)

I will probably contact Aristo about this but before I do does anyone know what the current policy is at Aristo on the old motors? I have two first run units that I would like to do a motor replacement. Will I need to send the motor blocks to them or will they send me the motors? Just curious if anyone has dealt with this lately.


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## eheading (Jan 5, 2008)

Paul, I would do as you said, contact Aristo. I do know they will replace the early motors on request. I suspect you'll have to send in the old motorblocks, but I do not know that for a fact.

Ed


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## Greg Elmassian (Jan 3, 2008)

Paul, call Navin, he sent just the motors to Ted Doskaris, at his request. 

Ted also has a vignette on the things you need to tweak to replace them. 

Ed, I know you reported the differences on your loco, I'm hoping for a second person to corroborate your findings, then I will list this on my site, good info. 

Regards, Greg


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## Paul Burch (Jan 2, 2008)

I e-mailed Navin at Aristo. He should be sending me four new motors. I'll print Teds info on changing them out.


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## Greg Elmassian (Jan 3, 2008)

Paul, when you go to change out your motors, can you take pictures and we can see if Ed's observations (version spotting guide if you will) can be corroborated? 

That info should help others, since there's so many questions about this. 

Regards, Greg


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## Paul Burch (Jan 2, 2008)

Greg,
Both my GP40's have been kitbashed. One is in fact now a GP38-2. The mu leads have been removed but I do remember them not coming out the holes like they should have. I can see the fan in the old as yet unremoved motors. The wheel plating has all but disappeared. I run battery power so this is not a concern except to note that the plating will come off even if you don't run track power.


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## Greg Elmassian (Jan 3, 2008)

Sure sounds like first run. 

If we can get pix of your original motors and of the new motors it would be great. 

Regards, Greg


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## JackM (Jul 29, 2008)

I e-mailed Navin at Aristo. 
I tried to call him, with no success. Could you let me know his email address, or is it the obvious "[email protected]" the website shown in their catalog website? My GP40's plating gave out after only one summer of moderate use. 

Right wheel after a light brushing:










JackM


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## Greg Elmassian (Jan 3, 2008)

please email me privately Jack. 

Greg


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## Paul Burch (Jan 2, 2008)

A little more on the GP40's. While changing the motors in my GP40's I also did a little work on the wheels which had serious wheel plating issues. After changing the motors and before reinstalling the blocks I clip corded the power leads to my workbench power supply and while running them put a small file to the treads and smoothed them out. After the file they were polished with some emery paper. I think they will be fine now for my battery operation. Back to the motors. I changed them out using Ted Doskaris's method which is available on Greg's website. Navin was very good about getting them to me. One of the blocks had a little growling in one of the gear boxes. Took it apart and found one of the bearings felt a little grindy when hand rotating it. I replaced it with one from a spare and all is well now. I don't know how common this is but I have read complaints about noisy Aristo motor blocks in the past. Could be one of the causes. Got a chance to give them a good test today plowing a little snow. Great fun.


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## Greg Elmassian (Jan 3, 2008)

Thanks for sharing the info Paul. Which bearing was "grindy"? The worm, or the worm gear/axle? 

Thanks, Greg


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## Paul Burch (Jan 2, 2008)

Greg,
The worm or drive shaft assembly, not the axle.


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## eheading (Jan 5, 2008)

What about the motors themselves, Paul? Do the look different from the original motors in your locomotive? My "first run" GP40 motors were open at one end so you could see that there was a squirell cage type fan inside. The motors in my "second run" GP40 just had slits in the housing to let, I presume, the cooling air in and out. Did you notice this same thing with your replacement motors? 

Thanks, 
Ed


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## Paul Burch (Jan 2, 2008)

Ed,
My observations on the motors are the same as yours. The new motors are slightly longer thus requiring the removal of the two small tabs that held the old motors in place. After the tabs are removed the new motors drop right into place.


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## eheading (Jan 5, 2008)

Yeah, I didn't replace my motors so I wasn't aware of the length issue. That is interesting, Paul. I just was going by my observations of the motors and how they looked already mounted in the trucks. I hope you have good luck with the new motors. I am very happy with the performance of my GP40 that is equipped with these newer motors. You know, I converted my original GP40 to FA trucks. I have been very happy with that. The new motors still use more power than the old FA type trucks, but I think they operate smoother an nicer than the other GP40 with the FA type trucks. 

Ed


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## Paul Burch (Jan 2, 2008)

Ed,
Mine got a test two days ago plowing snow. They ran fine. Not a hard job to change the motors out. The only modification is removing the two plastic tabs at one end of the craddle where the motor sits. I used a chisel tip exacto blade to slice them off.


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