Filing Wheel Flanges Down for Code 55 Track....

Sumner Jul 29, 2021

  1. Sumner

    Sumner TrainBoard Member

    After converting a '70's Minitrix FM H-12-44 to DCC I decided that it was time to tackle turning the wheel flanges down so that the loco would run better on ME Code 55 track. I'd heard of doing this and had read some descriptions on doing it but nothing in detail. I decided that I would document what I did and post it here on my site.

    Take the following with a grain of salt since I did this with very little actual knowledge of the exact steps others have followed. You might want to research this more and see what steps/procedures others have used to accomplish this and decide the best route for you.

    The day I did this I looked for NMRA standards for the height of the flange for N scale but only found what I believe to be the original standard of .035” as that is what this loco had when I measured the wheels/flanges on it. Since then I've found one post that states the standard for flange height is .022” and that matches the height on some MT trucks that I have.

    I did have a set of Kato GE U30C trucks that Spookshow calls low-profile and states they work fine on code 55 and they have for me also. I measured those and also a set of freight car wheels/trucks that I use when building hand-laid turnouts. To determine what I would use as a flange height I measured them.

    Truck Type ------------------Outer Flange Measurement ---- Wheel Diameter Measurement ---- Difference in Diameter ----Flange Depth

    GE U30C ------------------------------- .310 ------------------------------------- .254 ---------------------------------- .056 --------------------- .028
    Freight Car Truck -------------------- .270 ------------------------------------- .217 ---------------------------------- .054 --------------------- .027
    Stock Minitrix FM H-12-44 -------- .344 ------------------------------------- .274 ----------------------------------- .070 -------------------- .035
    Modified FM H-12-44 --------------- .332 ------------------------------------- .274 ----------------------------------- .058 -------------------- .029

    NOTE: Measurements above are in inches and were taken with dial calipers not a micrometer. For a better view of the data above go to my site ( HERE ).

    I worked with one truck at a time and the first took a couple hours as I made some mistakes. Was slow on getting the first truck frame off the wheels/axles and gear tower as I wasn't for sure how they came apart and didn't want to break one. Then lost one of the axle bearings getting to aggressive filing the flange down. The wheel I was filing came off the axle and I believe the bearing next to it must of come off at the same time. Spent 15 minutes looking for it but finally made a new on (more below).Then forgetting that the wheel/axles had to be put in the gear tower so that the insulated side of the wheels was on the same side as the wheel wiper I put one in backwards. I couldn't run the loco on my DCC++EX layout and it took a little while to figure out that the backwards wheel/axle was causing a short between the track rails. Also found out that the Arduino based DCC++EX Command Station does a good job of shutting track power when you have a short. Then I worried that I might have fried the Digitrax DZ16T decoder but it proved to have survived just fine.

    The main way I've found to avoid mistakes is not doing something in the first place but what is the fun in not learning something new because of your mistakes. I did the second truck in less than 30 minutes so now won't be intimidated by doing this job again if it is needed.

    With that out of the way let's move on the the actual modification to the wheels/flanges.


    It felt to me that I might break the frame getting it off but didn't. Gently pry out the end opposite the coupler and pull up on the gear tower at the same time.


    Take note of the fact there are electrical wheel wipers on one side of the truck and that is the side that the wheel that is insulated from the axle is also on. Make sure it is reassembled the same way (I didn't and lost time because of it).


    I used a battery powered drill I have and the wheel set down on top of the chuck with the chuck grabbing the wheel. Worked great and the wheels/axle turned very true with no wobble.


    I couldn't get a picture of the actual process but held the file on the table edge and then with the drill in the other hand filed down the flange. Take it easy. Press on the file hard enough that you see very small shavings coming off the flange.


    I got over aggressive on one wheel/axle set and the insulated wheel walked off the end of the axle onto the floor. Also the round bearing block on that side must of come off at the same time and disappeared. I'll probably find it a year or so from now. I made a new bearing block from some Plastruct 90603 3/32” styrene tubing. The inner diameter seemed perfect but the outside diameter was a little large for where it sits in the bearing tower. I filed the outer diameter down just a bit and it seems fine. The loco runs as good or better at low speed than it did before and it isn't like I'm going to put hundreds of hours on this loco. I also used ½ drop of Labelle's #108 oil on the axle. Take your time and this won't happen to you.


    I also carefully dressed up both sides of the flange a bit with the file. Don't take much off, taper it slightly on the wheel side and flatten it on the back side. I followed that with going over the filed surfaces very lightly with very fine sandpaper.


    I ended up being able to do a wheel in just a couple minutes.



    The main thing on reassembly is taking your time putting the one (to the right above) wheel axle in to avoid bending the wheel wiper (which I did the first time). Put the second (to the left) wheel/axle in the gear tower and then insert all of that down into the rear of the coupler housing at an angle. The other end of the gear tower will slide down onto the other wheel/axle.

    Then snap the plastic truck frame up onto the clips on the end of the gear tower.

    Be sure to put the large gear (not shown) back into the top of the gear tower before putting the gear tower/truck back into the frame. You then reinsert the metal pin that goes through the frame on both sides and the gear tower and the large gear. I used a toothpick to help center the gear while putting the pin back through.

    With the trucks oriented in the gear towers in the proper direction and not shorting the track the loco ran very smooth and with less noise. Didn't hit some of the ME code 55 rail/ties and went through the hand-laid turnouts really nice. In the video above or ( HERE ) you can see the loco goes through that near turnout better with less bumping around (that turnout isn't perfect so some of the problem is the turnout). The loco did run on the code 55 before the flange mod but now does run noticeably better.

    You can find the decoder install for this loco ( HERE ).

    In conclusion I was conservative on how much I reduced the flange height and according to the standards I could of maybe gone .010 inches further. The end result though was very close to the Kato GE U30C that I used as a standard and I'm happy with the results. In the future I'll take about the same off and won't worry if I take a touch more off the flanges.

    Link to this info on my site ( HERE ).

    Last edited: Jul 29, 2021
    eposte12, freddy_fo, newt749 and 6 others like this.
  2. Shortround

    Shortround TrainBoard Member

    Thanks for the info. I was a machinist/inspector so I do have the mics to check the size. Just wishing for a little lathe. And a mill. Etc., etc., etc...
  3. Doug Gosha

    Doug Gosha TrainBoard Member

    With my Atlas/Mehanotehnikas in the very early seventies, which had the deepest flanges of any N scale locos I've ever seen, I just filed the flanges down with a file and the loco powered up on its back. I took my time so as to not overheat the motor and covered any openings with masking ape. Easy.

    They all still run to this day and operate on code 55.

  4. PRR 65000

    PRR 65000 New Member

    I sanded down my flanges by rolling the trucks on sandpaper at a skew angle. Roll the truck, but twist it a little; the wheels still roll but a little sideways, so you get even flange reduction.
  5. r_i_straw

    r_i_straw Mostly N Scale Staff Member

    All my old Trix/Model Power and Arnold Rapido Pacifics got the flange treatment. I have an old Unimat lathe that I used to turn them down. I removed the drivers from the axles and temporarily mounted them on a piece of drill stock to turn them while filing down the flanges. I then had to press them back on their axles and quarter each driver set to get the correct offset. Here are two Trix mechanisms wheel to wheel to show the differences between stock and cut down.
    CSX Robert likes this.

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