Improvements for a Bachmann Spectrum 4-8-2 Mountain
#1
Hi All,

It's been a while since I've posted here but i've not been idle. Aside from redesigning part of my layout , redoing the track work etc. I've also finally given in to my weakness and taken my first careful steps in owning steam locomotive models. The first commercial plastic one I've bought is a Bachmann Spectrum 4-8-2 light Mountain. While I've already learned these were released a few times, with some technical differences/improvements in each. I think I might have one from the first or second release, and the PCB in the original tender almost appears as a non DCC version, but it does have a plug. In any case, I've swapped the tender for a long Vanderbilt type with two 3 axle trucks to more accurately represent the way they would have looked in service with the SP prior to them receiving the skyline casings.

I still have work to do on the detailing to make it a little more SP. Yes I know I could have tried to get an Athearn Genesis, but part of the fun for me is kit bashing/detailing, and it being my first steamer, I decided to go careful with the expenses and buying a loco for 50 USD is a lot better than 200+ USD. I've already rewired the tender and replaced the original bulbs for warm white LED's, and installed a Loksound V4 decoder with speaker in the tender.

However, to make a long story short. The loco isn't the smoothest runner I've seen. This may be because the engine has been sat in a box for years (allegedly it was brand new, but discovered during a clearcut) and all grease has dried up. So the first thing I did is to open up the cover for the axles and removed old grease and re lubricated it. This hasn't really made an improvement and I'm getting the impression that the drive is binding a little bit. Not enough to stall it, but just enough to make it move in a somewhat jerking/ irregular fashion at low speeds. I've also checked pickup wipers are free and not jamming in the spokes etc..

So anyone with experience with these engines (DCC or DC), what have you done to improve running characteristics?

Many thanks for your further tips and tricks in taming this otherwise nice model.

Koos
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#2
I have one of the early USRA Light Mountains, too, and had some issues with it early on. My maintenance records show that I fabricated a new connecting rod for the right-side valve gear (no date given), and in May of 2005, fabricated a new eccentric crank, also on the right side. At the same time, I found the drivers to be out-of-quarter, and after re-quartering them by-eye, applied ca to the engineer's (right) side drivers on axles 1 and 2, and to the Fireman's (left) side on axles 3 and 4.

I did have some issues with Bachmann's plug system, both with electrical continuity, and with the stiff wires often causing the front truck of the tender to derail. Since I run DC (and no headlights), in January of 2010, I removed the Bachmann circuit board from the tender and re-wired the loco so that it will run without its tender (useful for workbench operation using jumpers from a separate power source). I also installed new wiring between the loco and tender using mini-plugs.
The following month, I began re-wiring all Bachmann and Athearn steam locomotives in the same manner, and performance has generally been very reliable.

I re-detailed all of my locos to some degree, and I can't recall when the Mountain (it's a Mohawk on my layout) got modified, but in addition to the obvious changes, I replaced the air tanks under the walkways with lead-filled brass tubing. There's probably added weight internally, too, but it's been some time since it was done, and I can't recall for certain. The locomotive is a fairly smooth runner, if a bit noisy, and also a good puller.

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If you feel that there's some binding, and can't find any interference in the side rods or valve gear, check the drivers for proper "quarter". The easiest way to do this is to run the loco and then stop it with the driver counterweights on one side all at the bottom. If they all line up in pretty-much the same position, then that side is okay. Next, without moving the locomotive, look at the drivers on the opposite side: they should have the counterweights all in the same vertical position, towards either the front or rear of the locomotive.
There's usually enough "slop" in the mechanism that one or two counterweights a little out of step with the others shouldn't cause a problem, but if any are grossly out-of-step, they'll need to be re-aligned, then have some ca applied to the interface between driver and axle. The ca won't bond to the engineering plastic, but it usually turns the axle-into-wheel joint into an interference fit. When wheels get too far out-of-quarter, the locomotive won't run, and it may also damage some of the valve gear linkages, as was the case with mine.

While I do have a NWSL "Quarterer", I usually have good luck quartering "by eye", although it often still requires that the wheelsets be removed from the locomotive. In that case, clean oil and grease from the areas where you'll need to apply ca, and make sure, once the glue has set, that the wheelsets go back into the frame with the wheels on the proper sides.


Wayne
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#3
Thanks very much Wayne,

to be fair, I had a feeling you would be the one replying as I had spotted something resembling a Bachmann Mountain from you before and lo and behold, that was correct.
Anyway I will carefully check over the mechanisms and make sure everything is in quarter. I run DCC with Sound , so I do have to rely on the additional wires running between tender and loco so that the wires from the motor lead to the decoder.
I've also already identified issues with the pickups on the loco, some don't touch drivers very well, and others had moved a bit such that they interfered with the spokes on one of the wheels, that was quicly adjusted, but aside from that I'll check over the rest of the engine carefully and will share my findings here for everyone who may have one of these too.

Cheers!

Koos
Be sure to visit my model railroad blog at <!-- m --><a class="postlink" href="http://www.namrr.blogspot.com">http://www.namrr.blogspot.com</a><!-- m -->
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#4
This great thread inspired me to resume my kit-bashes on the 3 that I have.

I'm converting them to CNR U1s, beginning with #6047 which pulled the 1939 royal train from Jasper to Ontario.

Now for the reason behind this post, a word of caution.

I placed one of these on my test track to see if it still ran and noted the right ecctentric crank was about 90 degrees too far advanced, so I carefully tried to rotate it back, only to have it break in two!

On closer examination it proved to be pot-metal.

Excercise caution, these aren't as forgiving as the usual brass or nickel-silver types.

Dan M.
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#5
Eccentric-Crank Wrote:... noted the right eccentric crank was about 90 degrees too far advanced, so I carefully tried to rotate it back, only to have it break in two!

On closer examination it proved to be pot-metal.

Excercise caution, these aren't as forgiving as the usual brass or nickei-silver types.

Dan M.

Yeah, that's the same thing that happened to mine. I fabricated a new one, but I don't recall how or from what, though, as it was 12 years ago. I can take a look and see if it comes back to me. Crazy

Wayne
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#6
Yeah, that's the same thing that happened to mine. I fabricated a new one, but I don't recall how or from what, though, as it was 12 years ago. I can take a look and see if it comes back to me. Crazy

Wayne[/quote]

Thanks, please do.

Dan M.
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#7
It appears to be a piece of .040" thick sheet brass. It's shaped more-or-less to match the original, and that would have been done with a cut-off disc in my Dremel. There's another piece of .040" brass soldered to its rear face, to space it out from the drive rods - it's round, and may have also been shaped using a cut-off disc, or simply punched from sheet stock. The part was then drilled to accept the mounting screw, and probably countersunk, too, as the screwhead is flush with the outer face of the crank. There's no visible key to keep it from slipping out of position, though, and I hesitate to dismantle it in order to see what was done, as it's not caused any further problems.

I have a bunch of other stuff to do today, but I'll try to have a closer look at it tomorrow, and perhaps include some photos to provide more detail.

Wayne
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#8
Good luck with the mods,, I have three of the USRA heavy mountains, and all I can say about them is that they are solid, strong, runners. I am very pleased with them. I didn't have to do any modifications to the drives , but some of the tender trucks had to have the wheels re-gauged. The only detail changes that I did was to add feedwater heaters to the smokebox, a PRR style train phone to the tender deck, and some weathering. They are the only soft coal burners in the SH&D fleet.
 My other car is a locomotive, ARHS restoration crew  
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#9
In my case it appears that the contact wiper pressure was a little bit on the stiff side, some slight adjustments have improved that greatly.
I will however add a bit more of 'keep alive' capacity to this locomotive so bridge even larger power gaps but all in all the running qualities have improved reasonably well.

I'm now going to focus on changing some details to turn it into a better rendition of an SP Mountain pre skyline casing.

Cheers, Koos
Be sure to visit my model railroad blog at <!-- m --><a class="postlink" href="http://www.namrr.blogspot.com">http://www.namrr.blogspot.com</a><!-- m -->
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#10
Koos, what tender does yours have?

I've got a Roundhouse Atlantic kit with a Southern Pacific lettered Vanderbilt tender, and the Southern Railway prototype I want to build with it never had a Vandy.

If the Vandy tender is any use to you, I'd be happy to swap, if you are interested?
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#11
sorry, Daniel, life took over, and I've had little time for the hobby until now..

I don't need the tender, but thanks for the hobby. I have a 6 axle vanderbilt tender (by Bachmann) to go with my Mountain, so all good here.

Thanks!

Koos
Be sure to visit my model railroad blog at <!-- m --><a class="postlink" href="http://www.namrr.blogspot.com">http://www.namrr.blogspot.com</a><!-- m -->
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