I have a MTH HO Mikado 2-8-2 and the Front drivers climb the rails on 18" R curves. I read on a youtube video that if the front drivers derail, add a washer to the rear truck’s spring.
My questions are:
1.What is the rear truck spring?
3.What size washers and where to install them?
Does anyone have any pictures of what to do here?
Does anyone know what I’m talking about? 
Hi,
Check and make sure you have the front truck oriented properly.In almost all cases this is the culprit. Also,check over your track work very closely and make sure it is level with no abrupt changes(kinks),all the rail joints are snug and make sure your track is in gauge. MTH locomotives are very unforgiving on sloppy track work. I have over 40 MTH HO engines and I had to make several adjustments around the layout and I thought I had great track. It was my track-not the engines! Now I have NO problems with any of my engines(Genesis,Broadway,Atlas,Trix,Proto,Stewart,Intermountain).
Let us know how this works out.
Rick
Hi
I don’t have any MTH HO Mikes, but have had others and have read enough to know a few things.
1} Most Mikes WILL negotiate 18R" curves well and good enough enough, but some are picky. Many will even negotiate 15R" curves {my IHC did that just fine though it didn’t like it so much}, others not so much.
2} If the trackwork is not perfect, many engines will fail to negotiate the 18R" curves.
3}Yes, the trailing truck is the two wheels behind the drivers set and underneath the cab.
4}Adding weight to any part of a loco could be anything from sheet lead pieces to bee-bees to washers to anything that is small enough to add weight to the loco part needing weight to stay on the rails.
5} I am having a hard time and fail to see what adding weight to the rear trailing truck would have to do with keeping the front drivers on the track. I could be wrong. Perhaps if you saw a youtube video you could have provided us a link to that video???
6} No, not sure if I know what you are talking about.
7}If you used sectional track for your 18R" curves there should be little problems. But if you soldered flex track together, you may have an area that is “pinched” and the rails misalignment may cause the derailing.
8} for the price that MTH charges for it’s engines, if your trac
If all drive wheels are flanged, I can see that you would have this proplem. The 18" radius is really tight for a loco w/o blind center drivers. Another thing to check is the gauge of those drivers. If all are flanged, even if the center drive wheels are within gauge, they should be be to the min almost too narrow. If these are to the max of gauge they can force the front driver flange into the outer rail causing the climbing that you experience. Of course narrowing those center drivers is easier said than done. Any movement can throw them out of position and need requartering.
I have an MTH GS-4 (4-8-4) whose front drivers would pick certain frogs when diverging. I studied the engine and found that the front drivers were barely touching the rails. It was a weight imbalance problem. There was more weight on the rear drivers, and the driver axles being individually sprung, the engine was tending to squat backwards slightly. It was made worse by the pilot wheelframe spring lifting the front.
I did two things: 1. added as much lead weight as I could hide under the front; 2. removed the pilot spring and added lead weight to the wheelframe to give about the same downward pressure. With the improved balance, the front drivers are no longer almost floating. No more derailments. Seen these problems on other steamers as well.
Hal
Track work has to be flat in the curves
Any slight height variation will give problems especially on 8 wheel drivers
I had problems and had to take my track up ( ballast wasn’t down and was waiting till runs were OK ) and sand down the homesote base on one turn turn where there was a platform joint.
OK now