the MRH Forum

Re-powering questions Locos and rolling stock
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Regular poster 154 posts Hamms Regular poster 154 posts
Hamms
I have some older custom BB locos that I want to repower. Goal is to have gentle starts/stops and smooth low rpms; loco's will not be going very fast around the layout (30smph tops). I've read lots of suggestions in the past about hobby motors from Sagami, Mabuchi, Mashima, Kato, Helix Humper, PPW, Canon but many seem to have disappeared from the market.
 
I've tried a few of these so far with mixed/unsatisfactory results. I have some nib factory models that have Canon motors, and despite the glowing reviews, they studder badly at low speeds. I tried a mashima that runs no better than a tuned BB gold motor with tuned trucks. I've tried genisis and kato motors but they didn't do any better.
 
How does the motor rpm rating relate to low rpm torque?
 
What RPM rating is best for slow speeds?
 
What couplings (ball/socket, hex drive, silicone tubing) is the smoothest?
 
What motors that fit in an HO hood unit have you had the best success with?
Reply 2
blindog10 Prolific poster 4,939 posts
blindog10
If you didn't get good slow speed performance from a Kato the first thing I would question is your power supply. What is it? You give us that and we can let Professor K tell us all about it.
 
I've used A-Line's Athearn repower kits with good results. I know several others who have replaced all the Blue Box drive parts (motor, trucks, shafts, universals) with Kato parts.
 
I have a couple Athearn RTR (yellow box, circa 2005-2010) that run very smooth and quiet. But they don't all do that.
 
And frankly, most of the Atlas Master and Classic drives (Chinese made) are damn good.
 
Scott Chatfield
Reply 4
Hamms Regular poster 154 posts
Hamms
My best running bb still has it's gold motor. The motor swaps all seem to suffer from jerking studdering at startup and crawling speeds. Most of my factory atlas/katos run very well. Just dissapointed that the motor swaps I've tried so far didn't improve the bb.
 
Power supply is a collection of DC throttles, MRC 3000, MRC 200, MRC 220, ITTC Innovator, GML Rover, and an adaptation of the Cooler Crawler.
Reply 1
Rodney Edington Rods UP 9000 Regular poster 463 posts
Rodney Edington Rods UP 9000
Just dissapointed that the motor swaps I've tried so far didn't improve the bb
 
 Now you know the problem isn't the motor. Look at replacing the trucks next
 Later
 
Rodney
 
Reply 1
Hamms Regular poster 154 posts
Hamms
Motor swaps was in the best bb runner (SD9 chassis). Electrically isolated. Sorted through all of my trucks, hand picked the best gears and worms. Shimmed the worm end play. Also tried some brand new trucks just in case. Swapped to thinner idler gears and NS wheelsets. Trucks roll very freely. No change in low speed performance with motor swap. Haven't put too much effort into the switchers yet. So now I'm asking for more details about motor rpm ratings and driveline couplings.
Reply 1
Graham Line Prolific poster 1,467 posts
Graham Line
The problem still could be in the continuity of the electrical pickup path, particularly if the loco stutters at low speeds. There could be oxidized metal-to-metal contacts, worn bronze wipers or just poor contact in general. In A-LIne's repowering heyday, their mechanisms got a lot of handwork and soldered wiring paths. My benchmark locomotive is a fairly old Atlas ALCo RS1 that has jumpers around all of the wiper contacts.
Reply 1
Andy Reichert Super User 2,589 posts
Andy Reichert
My approach would be to try and discover what is causing the symptoms with the problem loco you have, before you start swapping out motors, parts etc.  The earlier advice about bypassing any rubbing or wiping electric al contacts to see if it makes a difference is a very good idea, as is looking for stiffness or incorrect movement in any part of the transmission, from the axles, all the way to the motor shaft, and unevenness or rocking with the chassis sitting on a flat piece of glass.
 
Andy
Reply 1
Northof49 Regular poster 194 posts
Northof49
 Micromark is a good reliable source for motors, and NWSL sells driveline parts (shafts and universals). NWSL also sells excellent motors, but they are pricey.
 
I successfully remotored an SD40. Changed the wheels as well. The BB gear noise is still there, but motor control is good.
 
Simon
Reply 1
Mark Pruitt Pruitt Prolific poster 2,008 posts
Mark Pruitt Pruitt
You might ask the folks on the repower and regear IO group. This kind of thing is what they do, and they're always ready to give advice.

Mark P.

http://www.thecbandqinwyoming.com
https://www.youtube.com/user/mabrunton

Reply 2
Distracted Perfectionist Regular poster 214 posts
Distracted Perfectionist
I’ve tried this sort of thing with Kato, Atlas, Mashima and motors off of eBay. As long as the mechanism is good, and the electrics are solid, you can get excellent control from BB mechanisms. That said I like to replace the lot, but it doesn’t have to be a total replacement.
Distracted Perfectionist
Failing miserably but (mostly) enjoying the process - modelling the D&H in HO scale
Reply 1
Nelsonb111563 Moderator 2,588 posts
Nelsonb111563
No matter the age, a complete teardown of the entire drive system, thorough cleaning of ALL grease and reassembly using only very light oil will improve your performance drastically! The gold can motors especially those with a skewed armature run very well and draw little power so it's not usually the motor. Exactly which BB models are we talking about? What vintage? Ring magnet motor? Silver side? Gold? Or gold side with skewed armature?  The particular model should not matter as the same criteria applies across the board. The older they are the more finicky they will be but all can be made to run well with some basic tuneup tricks!  

Nelson Beaudry,  Principle/CEO

Kennebec, Penobscot and Northern RR Co.
Reply 2
Mark Pruitt Pruitt Prolific poster 2,008 posts
Mark Pruitt Pruitt
The only difference between what Nelson said and what I do when I lube / tune a mechanism is that I put a dab (emphasis on DAB) of Labelle teflon-impregnated grease on the gear teeth and the worm, rather than oil. Grease is a bit thicker and tends to stay in the teeth better than oil does, though in our lightly loaded gear trains it probably doesn't make much difference. I use oil on all bearings and crosshead guides (in the case of a steamer).

Mark P.

http://www.thecbandqinwyoming.com
https://www.youtube.com/user/mabrunton

Reply 2
Hamms Regular poster 154 posts
Hamms
SD9, it's a later production with gold case, brass flywheels, plastic truck side frames. After a tune up and upgraded trucks it actually runs really smooth, and I was hoping that a motor swap would make it even better, but surprisingly with Kato and Genesis motors it actually got worse at very low rpm, which makes me wonder if it's a case of matching the motor speed rating with the gear ratios. Maybe I'll just leave it as good enough.
 
The rest are the SW switchers. I'm in the process of test fitting concor/kato drives into the athearn shells, but the truck towers are a tight clearance.
 
I will check out the repower group and see what they can tell me about motor rpm ratings and low rpm torque.
Reply 2
Distracted Perfectionist Regular poster 214 posts
Distracted Perfectionist
Keep us posted on your progress, it’d be good to see if you find any different solutions.
Distracted Perfectionist
Failing miserably but (mostly) enjoying the process - modelling the D&H in HO scale
Reply 0
Rasselmag Frequent poster 729 posts
Rasselmag
Hamms,
 
the key for smooth running at low speeds is cogging. Turn your motors by hand and pay attention to cogging torque. Those motors with tactile cogging are never useable smooth slow runners, they are cogging from one arrester ton another. This is causing a jerky start and stuttering running at low speeds.
These coggers are candidates for replacement.
 
As with Athearn motors the lot is so-so. Some motors are running like crap and on the other hand there are really excellent smooth running motors.
Keep the smooth running ones and replace the crappy runners.
 
If choosing replacement motors do the test by turning them by the means of your fingers and pay attention to cogging behavior.
 
 
Lutz
Reply 0
Nelsonb111563 Moderator 2,588 posts
Nelsonb111563
SD9, it's a later production with gold case, brass flywheels, plastic truck side frames. After a tune up and upgraded trucks it actually runs really smooth, and I was hoping that a motor swap would make it even better, but surprisingly with Kato and Genesis motors it actually got worse at very low rpm, which makes me wonder if it's a case of matching the motor speed rating with the gear ratios. Maybe I'll just leave it as good enough.
 
The rest are the SW switchers. I'm in the process of test fitting concor/kato drives into the athearn shells, but the truck towers are a tight clearance.
 
I will check out the repower group and see what they can tell me about motor rpm ratings and low rpm torque.
I honestly never had good luck repowering the the Athearn drive system. I fully believe that they are matched as good as they can get.
As long as it will run well under DC power, it will run well under DCC power most times better because almost all high-end decoders have BEMF that senses the motor input/output/load ect. and can adjust the motor speed on the fly.   I have tried KATO motors, Mashima and various others all with mixed results.  
The big repowering craze was back in the 1970's through mid 1990's because there were a lot of models with the old JET 600 (I call these the ring magnet ) and the early silversides with the metal flywheels. These all had straight wound 5 pole motors. As the newer ones started coming out with the gold sides at some point Athearn switched over to 5 pole skew wound motors effectively eliminating the cogging issue.  The straight wound motors can still be made to run very well and this is where BEMF decoders really shine.

Nelson Beaudry,  Principle/CEO

Kennebec, Penobscot and Northern RR Co.
Reply 1
Hamms Regular poster 154 posts
Hamms
Good to know, maybe I'm chasing my tail trying to motor swap the BB. The full size frame motors run pretty good, but switcher motors are rough.
 
I tried DCC sound and didn't care for the drone from tiny speakers, so I'm back to DC for now and designing my own throttle. Probably one of very few to go "backwards".
 
I did figure out why the Stewart models with AJIN Canon drives were so noisy and visibly shuddering at low speeds. I was doing testing with an O-scope and the ITTC and GML throttles, both of which can select from flat or pulsed DC, and turns out the Canon motors really hate pulsed power. On flat DC they ran much better, but of course had really poor lurching from a stop typical of a pure DC throttle. I suspect that the Canon motors are more powerful and amplifying the pulses into the trucks and frame.
 
The comment about cogging sounds correct, and I would suspect that skewed armatures would perform better. The kato don't seem to have very much cogging effort even though they are a straight 5 pole, which would explain why they run so good in factory drives.
Reply 0
Distracted Perfectionist Regular poster 214 posts
Distracted Perfectionist
That’s an interesting observation about the switchers, although I’ve tended to lean almost exclusively towards the SW1500 (the proper one not the incorrectly marked up SW1200), and they have always had gold side motors, I find they have been the better runners.  I will add that almost all were bought second hand so I have no idea how they were treat before I purchased them.
 
With regards to chasing your tail, you could be right, but perhaps not how you think. It all depends on what your standard is and whether you can attain it with the desired effort. As mentioned I like to replace full drives, it’s as much for the joy of it than anything, but I much prefer the current pick-up through the phosphor bronze pick-up bars on Kato, Atlas, Stewart etc.  and the performance is always markedly better with much less effort using these parts.
 
I suspect that some blue box you will not be happy with and others will run just fine, as I have found, so it might be that some get replacement parts and others you are happy to leave alone. Certainly that has been my experience but if you’re fitting sound, sometimes it’s better to replace that large motor assembly with something more discrete so that you can get a decent sized speaker in there.
Distracted Perfectionist
Failing miserably but (mostly) enjoying the process - modelling the D&H in HO scale
Reply 0
peter-f Prolific poster 2,145 posts
peter-f
You might ask the folks on the repower and regear IO group. This kind of thing is what they do, and they're always ready to give advice.
Came here to refer this group ... I lurk over there and have learned a bit just reading.  
- regards

Peter
Reply 0
Kelly kregan Regular poster 329 posts
Kelly kregan
I have never had a Kato motor stutter if the electrical pickup was sufficient. To that end I mill my own frames to install Kato trucks and motors into my Proto 2000 GP7's, 9's, and and 30.

Kelly,

Modeling the Georgetown Branch in HO Scale
Reply 0
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