hello i’m in the prcess of building a small L shaped layout. i glued and ballasted the track directly on the 1/2 foam which is glued to a hollow door. when i tested my atlas gp7 it ran great at low speeds but if it went a lil faster the track makes a crunching sound like it is crunching he ballast under the track and more so on the 22 radius curve, any ideas how to correct this also the athearn cars with the metal wheels also makes a louder sound, and i forgot to mention this is HO scale.
I suspect that the 1/2" which is not that thick really is transmitting the sound to the hollow door where it is being amplified. The ties could be rubbing the ballast causing the crunching sound, just an idea. Maybe try pushing with various speeds and hardness on the track at different places to see if you can make some sort of sound. If it makes a sound you don’t like you may want to replace that hollow door and add some more foam along with plywood.
What your hearing is normal when using a hollow door. Your going to have to either live with it or fill it up with some sort of sound deadener. Expanding foam works great. Drill a few holes in the bottom and start spraying. There is the possibility of it coming out the other side if there is any type of hole or crack and of course the door will be heavier.
Also take a look at the inside of the rails to make sure ballast isn’t stuck to them. Also take a piece of rolling stock and run it around the areas you hear the sound with your hand. You’ll feel if the flanges are hitting something.
I work in the residential replacement window business (as well as other products) so I have had some experience with foam. If you put too much foam in the space beside the window you will bend the frame and might even crack the glass.
First, some foams are classified as 'low expansion". They have a more controlled rate of expansion. The cheaper foams will generally expand more quickly but if you provide enough space for excess foam to escape the door should not swell. I would suggest maybe 1 1/2" or so for the overflow holes to allow the foam to escape. The injection holes should be the same size as the nozzle so the foam won’t come back out at you. Make sure you shake the can thoroughly and follow the recommendations regarding ambient temperature.
You should be aware that most hollow core doors have some sort of spacer inside to keep the skins from flexing. I would cut a couple of larger holes at one end and then use a wire probe to see if you can figure out the position of the spacers. Some are just a simple zig-zag of cardboard, others may be in a diamond pattern. Your supplier or manufacturer may be able to tell you what shape they are. You will need to inject into each separate void and you will want an exhaust hole for each as well. Try to have the injection hole at one end of the void and the exhaust hole at the other. As soon as you see the foam at the ehaust hole stop pumping. If you have a diamond pattern spacer this will mean a lot of holes and could be a PITA! I would not worry about filling each void perfectly. If you fill most of the space it will work. The holes will not affect the structural integrity of the door. Once the foam sets you will probably be able to put it across saw horses and jump up and down on it without doing any harm.
Hope this helps. Sorry if it seems like too much information
Have recently tried low expansion foam; advertised on can as being better for filling window/door gaps. Noticed that, after it has cured, it remains a bit pliable. THIS type foam may be a better choice for sound-deadening on h/c layout doors. My 2 cents. Good Luck…Old Tom aka papasmurf in NH
It appear that the track nails are transmitting the sound to the hollow core door. I removed the track nails after I ballasted(10 years after I laid the track). Right now I have Atlas flex held down with Arizona Rock & Mineral ballast/matte medium) on Homabed roadbed that is glued to 1/2" plywood with wood glue. It is quite quiet and my sound engines can be heard!
i have a bunch of atlas gp-7’s on my layout, most of which is still bare plywood or cork. nothing is ballasted yet. the atlas engines always make kind of a “munching” or grinding sound when working. it is directly related to speed. they are in good order gear wise and i keep them lubricated. i think it is just the nature of the beast. actually, it doesn’t sound all that bad. no doubt your layout base and trackwork can amplify the noise.
ok most of the annoying sound is gone so next step is to wipe the track down with that rubbing alcohol stuff then a few drops of wahl clipper oil and let the engine run on the tracks