19 Jan2018

Body-Mounting Kadee Couplers

Written by Larry Cooper. Posted in Couplers & Trucks

BEFORE BEFORE AFTER AFTER

Introduction and Overview

In my personal quest for more realism in my 1/29 models and more reliable operation of long trains, I have made the decision to body mount all my couplers. Since this is an area that only a few venture into but many are curious about, I thought you might like to see a little more information on the subject.

The couplers that come on most Large Scale cars from the factory are grossly oversize. When combined with the extremely short radius curves of the original factory track systems, the truck mounting of these couplers makes long trains impossible and contributes to many derailments. Replacing these with Kadee couplers and body mounting them can repair both of these problems.

Should You Consider Body Mounting?

First, let's talk about the physical stuff. If you are still using any really small radius curves (say less than 6 ft. diameter) or if your trackwork undulates up and down a lot (this is especially a problem if your layout is outdoors) you may not be a candidate for body mounted couplers. The factory couplers were designed with these limiting factors in mind and you should retain them. If you have already fixed these problems, then you could benefit from body mounted couplers, running longer, more prototypical looking trains with fewer cars pulled off the track on curves.

Success with body mounted couplers can best be obtained when strict track, wheel, and height standards are rigorously implemented on your layout. Repeating, for emphasis, success with body mounted couplers has more to do with good, prototypical (long radius curves and switches) trackwork than any other factor. I model indoors on hand-laid track in order to be able to better control these elements of my hobby and, as a result, have had no problems at all with finer flanges, more tightly laid switches and crossovers or with body mounted couplers. However, outdoor railroaders can adhere to the same standards by using the new larger radius curves and paying some attention to seasonal maintenance.

If you are like me and want to see more realism in your Large Scale Railroading then this article may help.

Correct Height Cars?

Next let me say that I am writing this article, and illustrating it, from the perspective of mounting Kadee #820 couplers on to cars that are the "correct" height off of the rails. This implies that, if the original car stands too high off the rails, it must be lowered to the correct height first and then the techniques I describe will work without modification. (See my other article on LOWERING ARISTO BOX CARS TO IMPROVE THEIR SCALE APPEARANCE).

One of the things that affects this height is the diameter of the car's wheels. I am using MDC plastic wheels that are slightly smaller than the original Aristo Wheels. The MDC wheels measure 1.175 inches in major diameter at the tread while the Aristo wheels measure 1.195 inches. (See my other article – Project #1 IMPROVING ARISTO’S FREIGHT CAR TRUCKS).

An Essential First Step

One thing you will most certainly want to do is cut off the truck mounted coupler tongue that is built into the truck bolster. For both freight and passenger car trucks, it is a simple cut across the width and then some dress up filing to clean the piece up.

In the process of cutting. The finished product.

Order of Presentation

I will be describing how to body mount Kadee #820 couplers on several different cars, progressing from the simplest task to the most complex, as measured by the difficulty encountered in making the "coupler height” adapters. Here is the order of the cars that I will present:

Aristo Flat Cars and Gondola Cars, which are at the correct floor height right out of the box.
LGB 40 foot Box Cars, which require only a very simple coupler height adapter.
USA Trains Depressed Center Flats, which require a slightly more complex height adapter.
USA Trains "Ultimate" Series Box Cars and Reefers, which only require a simple adapter.
Aristo Tank Cars, which only require only a simple adapter.
LGB Airslide Triple Hoppers, which require a slightly more complex adapter.
Aristo Box, Stock, and Reefer Cars, which must be lowered & require a slightly more complex adapter.
USA Trains 3 bay Hopper Cars
Aristo 3 bay Hopper Cars
MDC 2 bay Hopper Cars
USA Trains Cabeese, which are at the right floor height but require a complex adapter.
Aristo 2 Bay Covered Hoppers, which must be lowered and require an even more complex adapter.
Aristo Streamlined Passenger Cars, which must be lowered and require a pretty thick adapter.
USA Trains Streamlined Passenger Cars, which require a pretty thick adapter
Aristo Heavyweight Passenger Cars, which are the right floor height but require a complex adapter.
Aristo FA and FB locomotives
Aristo RS-3 locomotives
USA Trains GP-7 locomotives
Aristo Vanderbilt Tender
Aristo Pacific Tender
LGB Mikado Tender
USA Trains Hudson Tender

A note of interest to those of you who may want to try one of these projects. Since my goal is to make it possible to pull long trains, it makes sense that I should use the largest screws that I can to attach the couplers without them looking unsightly. This spreads the tension over a larger surface area and makes the mounting more sturdy. In addition, I needed to choose a size of screw that is readily available at my local hardware store, since I do not live near a large hobby shop. In light of these considerations, I chose 4-40 machine screws to mount my couplers. If you have them, 2-56 will work too, but not be quite as strong.

I have had great luck with body mounting my couplers. I hope that this article helps you to have the same experience.

Adding Body Mounted Kadees to Aristo Flats and Gons

Let's start with the easiest car there is for this kind of project - the Aristo Flat and Gondola cars.

The unique construction of these cars, with the underframe mounted up inside the car sides, causes these cars to ride at almost the correct height right out of the box. The cast floor used in these cars is the same as that used for the Aristo box cars, reefers and stock cars in their original line of rolling stock, and it includes an improperly shaped and height body bolster that the trucks attach to. In the box cars, with the way their floors are mounted, this causes the car to be too high off the rails, but in these flats and gons, the vertical inset of the floor corrects this problem and the cars ride very near their correct height. This means that no coupler height adapter is needed, unlike the cars that follow.

The first step in this conversion will be to invert the car and remove the trucks. You will need to cut the coupler mounting tongue off of the truck, as we mentioned earlier in this article and put the large, unrealistic Aristo coupler in your scrap bin or sell them to other modelers on e-bay.

This leaves a bare end area like this:

Now we need to drill some holes in the plastic with a #43 drill bit (.089).

Place the Kadee #820 draft gear on the end of the car with the flange up against the car end, resting on the bottom of both the end of the car and the "coupler extension support tab" as shown below:

Now let's use this assembly as a jig to PARTIALLY DRILL two #43 holes through the side mount holes.

Make sure that you do not drill all the way through both layers of plastic. There is an underframe layer and then, next, the actual inside of the car floor. You can tell when you have started to drill through the inside of the car floor because the drill bit shavings will change color. Stop when you see that sign. DO NOT DRILL THROUGH THE CAR FLOOR or else the screws we use will show on the inside of the car.

See the image and note that I am angling the drill bit tip back toward the center of the car just a bit to ensure a snug fit.

When these two holes are drilled, the car end should look like this.

Now we will mount the Kadee #820 draft gear with two 4-40 round headed machine screws that are 3/4 inch long. These should self tap through the two #43 holes you just drilled and will only be long enough to go through and engage the underframe layer of plastic. Snug these screws down.

To ensure that the draft gear is secure, we will drill one more #43 hole. Carefully drill a hole straight down into the "coupler extension support tab" through the rearmost hole in the Kadee draft gear, as shown in this image:

Insert a 4-40 round headed machine screw that is 1/2 inch long into the hole you just drilled and snug it down. You should find that, if you tighten all the screws enough, they clamp down on the Kadee so tight that it refuses to swing. Starting with the side screws, back the screw off on each side evenly until the coupler head swings freely.

Repeat this whole process for the other end of the car. When finished, the car should look like this:

Testing for Correct Height

Re-attach the trucks, minus their coupler tongues, and place the car on the rails.

I use a Kadee #1 gauge coupler height gauge and I recommend that you do too.

In any case, make some kind of gauge that will allow you to apply the same standard measurement to all your cars without using another car to judge the correct height.

I think you will find that these cars, and their couplers, are now the correct height and that these are the simplest cars to perform this conversion on.

Building on what we have learned so far, we now go on to a car that is just slightly a bit more tricky.

Adding Body Mounted Kadees to LGB Box Cars

The process for LGB box cars is quite simple since, like the Aristo flats and gons and the USA Trains Depressed Center flats, the LGB Box Cars do not need to be lowered.

Start by removing the trucks and cut the coupler mounting tongue off of the truck and put the large, unrealistic LGB Horn/Hook coupler in your scrap bin.

Now drill two #43 holes in the car floor along the centerline spaced at .480 and 1.440 inches from the outside edge of the car end respectively. You can us

e the Kadee draft gear as a template by just setting the draft gear with it’s lip up against the end of the car and marking the holes on the floor. When finished, the car end will look like this:

The positioning of these holes is very important because, in determining the location of the Kadee draft gear, they can affect the overhang and car spacing adversely if done incorrectly. This hole spacing has been arrived at by trial and error and produces a mounting that just sticks out over the edge of the car and spaces cars apart about 1 inch. If you have a lot of cars to do, you can construct a drill guide so they will all be the same, as I did.

The LGB Box Car Coupler Height Adapter

Even though this car is sitting at the correct height, if the couplers were mounted directly under the floor, they would be a little too high, so we are going to introduce, at this time, the concept of a “coupler height adapter”. The piece for this car is as simple as it gets. Simply start with some 1/8" thick by 3/4" wide stock. Plastic will do but I found some aluminum bar stock at my local hardware store and used it. Cut the stock to just fit between the body bolster and the inside lip of the car end. Drill two oversize holes in this piece to provide wiggle room for the 4/40 screws (try a 1/4 drill bit).

Now file all the burrs off and paint the piece flat black so that it looks like this.

Place the adapter on the car end like this:

Next mount the Kadee #820 draft gear using two 4/40 by 5/8ths inch long round head machine screws by screwing them into the plastic and allowing them to self tap as on the Aristo car. Snug them down until the coupler shank starts to stick in it's swing and then back off 1/4 turn.

Repeat this process for the other end of the car. Replace the trucks and turn the car over and it should look like this:

Testing for Correct Height

As before, test with a coupler height gauge but I think you will find that it comes out just fine.

Adding Body Mounted Kadees to USA Trains Depressed Center Flat Cars

The process for USA Trains Depressed Center Flat cars is similar to the LGB Box cars we have already talked about. Like the Aristo flats and gons and the LGB Box cars, the Depressed Center flats do not need to be lowered. However, we are going to introduce a different method for attaching the coupler height adapter in this effort and we will need a variation of it again later for a USA Trains caboose. In this special effort we will use 2-56 machine screws instead of the 4-40 screws we have used up till now.

Let’s start by removing the trucks and cut the coupler mounting tongue off of the truck and put the large, unrealistic LGB Horn/Hook coupler in your scrap bin. When finished you will have a surface that looks like this:

The Depressed Center Flat Car Coupler Height Adapter

Before doing anything else, we will go on to making the coupler height adapter because we will need to drill holes in the frame using it as a template.

For this adapter, I use metal because it is convenient and because I trust the 2-56 screws more if they are threaded into metal. Start with a piece of material that is 3/16 ths of an inch thick (or, if you can find it, .20 bar stock). It should be 1 and ¼ inches wide and 1 and 15/16th inches long. A special shape is my preference here, where the edge of the piece that shows on the end of the car is only as wide as the coupler raft gear, like this:

While this shape may not be absolutely necessary, when you do it this way the finished product looks much better, as you will see later on.

If you look carefully at the piece above, you will see that we have drilled 2 small holes very near the edges on each side. These are clearance holes for the 2-56 machine screw we will use to attach the adapter to the frame. They are created by using a #43 or #44 drill bit.

When drilling holes like this, that have to be precisely at a certain spot on the piece, it is best to mark the center of the holes with a hammer and a pointed center punch. Then the drill bit will not wander as you start the drilling process.

Once you have drilled the holes successfully through the edges of the adapter, you should lay the piece on the car frame in it’s correct final position and carefully mark through the holes you just drilled onto the frame for the tap holes. These tap holes are for the 2-56 machine screws we will use to attach the piece to the frame.

For the frame tap holes we will use a #50 drill bit, and will make sure not to wobble as we drill so that holes in the frame come out as close to that #50 diameter as possible. Wobbling makes the holes oversize, so avoid it in this operation especially.

Now place the piece on your workbench and position the Kadee 820 draft gear on the adapter as it will be when mounted on the car, with the top lip just over the edge of the end of the piece. Put a mark through the two center holes in the draft gear. Removing the draft gear that you have used as a template, carefully drill the two holes you have just marked with a #50 drill bit and, if you have used metal for the adapter, thread the holes with a 2-56 tap. Paint the adapter flat black and let it dry.

Now we are ready for assembly. Using four 2-56 round head machine screws that are 3/8ths inch long, attach the adapter to the frame through the edge holes. When finished, your car end will look like this:

Now we can finish up by using two 2-56 round head machine screws that are 5/8ths inch long to attach the Kadee coupler draft gear to the adapter so that the car end now looks like this:

Now let’s repeat the process for the other side, reattach the trucks and you will have a car that looks like this:

Testing for Correct Height

As before, test with a coupler height gauge but I think you will find that it comes out just fine.

Adding Body Mount Kadees to Aristo Box Cars

While the title of this section states "Box Cars" it should be obvious that the same technique applies to Aristo Stock Cars and Aristo Reefers as well. Rememeber that these cars come from that factory standing 3/16th too tall off the rails and need to be lowered to achieve the realism we seek.

Start the coupler conversion process by inverting the car and removing the trucks.

You will need to cut the coupler mounting tongue off of the truck and put the large, unrealistic Aristo coupler in your scrap bin.

When finished, you will be presented with this view.

Now drill two holes in the floor with a #43 drill bit (.089 diameter) approximately .40 from the outside edge of the end of the car and .70 apart so that the midline of the distance between the holes is on the centerline of the car.

I use a jig that ensures that the holes are centered and in virtually the same place every time.

The positioning of these holes is very important because it determines the location of the Kadee draft gear and can affect the overhang and car spacing adversely if done incorrectly.

When you are finished, you will be presented with this view.

The Aristo Box Car Coupler Height Adapter

Now make a Coupler Height Adapter like the one shown in this picture.

The Coupler Height Adapter is a simple piece of plastic (mine is a casting) that is no wider than the Kadee coupler body. Mine is 1/2 inch wide.

The adapter's length can either be short or long. The short version, as shown, is made to match the distance to the end of the car from the "coupler extension support tab" that is cast into the floor and measures approximately 1.1 inches long. The long version would be made to match the distance between the truck bolster and the end of the car in cases where you had removed the "coupler extension support tab".

The most important dimension for this adapter is it's thickness. For Aristo Box Cars that have been lowered by 3/16th of an inch, the thickness should be .155 inches. If you have not lowered your car then it should be .3425 inches (.155+.1875 inches).

I put a 1/4 inch diameter hole in my adapter to permit the head of the attachment screw on the end of the body to have some clearance. You might want to do the same.

I also made a small lip on the end of my adapter to allow it to space the Kadee coupler out from the end of the body by about .040 of an inch to create the car spacing I was looking for and to present a pleasing visual image. The height of the lip is about .040 inches as well. However, this lip is optional as long as the #43 holes are drilled correctly as noted above.

When you have made the adapter (by the way, I have these castings available and will gladly share them with anyone who wants to copy them) you should paint it flat black and place it on the car floor as shown.

Now assemble the Kadee #820 coupler components and note that they come with a mounting hole on the back end of the coupler. I trim this off to produce a flat-backed piece that then buts up against the "coupler extension support tab" that is cast into the floor. You would not need to do this if you have removed that tab.

I now place two round head 4-40 x 5/8ths machine screws in the two side holes on the Kadee coupler body and screw them into the plastic. The #43 holes that you drilled earlier are the correct diameter to permit these screws to self tap and you will find that they go in very snuggly and will hold forever without a nut on the inside of the car.

Tighten these screws until the coupler sits parallel to the car body and the coupler shank just swings freely. Take care to make sure that the adapter is centered on the Kadee draft gear. I snug them down until the coupler shank sticks a little and then back them off a quarter turn.

When finished, it should look like this.

Testing for Correct Height and Spacing

Re-attach the trucks, minus their coupler tongues, and place the car on the rails.

I use a Kadee #1 gauge coupler height gauge and I recommend that you do too.

In any case, make some kind of gauge that will allow you to apply the same standard measurement to all your cars without using another car to judge the correct height. If your adapter is the correct thickness, as outlined above, you should see this image when you measure the coupler's height.

And if you positioned the #43 holes so that the Kadee draft gear just overhangs the end of the car, you should have about 1 inch of clearance between two coupled cars. I have found this to be satisfactory for all my trackwork and it presents a pleasing visual image.

Adding Body-Mounted Kadees to USA Trains Cabeese

The new USA Trains extended vision and bay window caboose models are a beauty to behold but they present a real problem when trying to body mount couplers.

The area where you would normally put a machine screw to hold the draft gear is a see-through casting that is so beautifully done and so delicate that I hated to mar it with screw heads.

I also wanted to develope a method that would not require the removal of the trucks so that the modeler would not have to unsolder the pick-up wires.

To meet this challenge, I developed another coupler height adapter that fixed the problem.

Through trial and error I found the right dimensions and used a longer adapter style that allowed me to put 4 small 2/56 flat headed machine screws into the underside of the frame of the car in a hidden location. This permitted me to attach the coupler draft gear to the adapter without drilling any holes in the see-through walkway on the end of the car.

The USA TRAINS Caboose Coupler Height Adapter

Here is a picture of the adapter before I countersunk some of the holes.

The adapter started out as a piece of aluminum stock 1/4 inch thick and 1 inch wide. I cut it to be just under 2 inches long. I drilled 4 holes on the end of the block with a #44 drill bit to clear the shaft of a 2/56 machine screw. Placing these holes is not very critical except that they need to be along the edges (preferably within .1 of the edge) and no further from the end than 3/4 of an inch. On my piece the two end holes are .1 inches from the end and the side edge and the other two holes are .1 from the edge and .75 from the end.

Next, drill two 1/8 holes on the centerline of the piece at the opposite end from the 4 holes you just drilled. On my piece they are .330 inches and .990 inches from the other end respectively.

Now comes the tough part. I temporarily mounted the Kadee #820 draft gear to this block using the two holes you just drilled and some 4/40 flat head machine screws. Next I traced the outline of the daft gear in the metal.

Removing the draft gear and the machine screws, I then mounted the block in my milling machine and removed material to thin out the place where the draft gear was going to be mounted so that what remained was .10 inches thick.

After this I used a countersink bit to prepare all the holes for flat head screws. For the two 4/40 crews I countersunk on the side that will be the top of the piece. On the four holes for 2/56 screws I countersunk on the other side (the bottom of the piece).

Here is a picture of the adapter mounted on the underside of the car with Kadee #820 daft gear attached.

Here is a picture of the end of the car after the coupler has been attached.

Finally, here is a picture of the walkway showing that it has been undisturbed by my conversion.

Testing for Correct Height

Naturally, as with all these conversions, the final step is a check with the Coupler Height Gauge. Since this car sits about the correct height off the rails right out of the box, this adaption method should bring the coupler height right to within specs.

Another Approach by Brandy Bruce-Sharp

I normally favor a physical attachment of couplers with machine screws to make sure that the attachment can withstand the significant forces that long trains can put on them. However, in the case of a caboose which only appears at the end of a train, the couplers are only pulling the weight of that one car. In this special circumstance, other attachment methods may become more convenient.

One such method was recenlty employed by Brandy Bruce-Sharp, who should need no introductions since he has also written articles for Large Scale Central.

Brandy made up a special coupler adapter to mount a Kadee #821 shortened draft gear unit. His drawing of the styrene assembly is shown in this image.

Brandy used Cyano-Acrylic glue to bond the adapter to the caboose frame, as shown in this image.

Whether you use my method or Brandy's, the finished product looks great!

ADDING BODY MOUNTED KADEES TO ARISTO COVERED HOPPERS

In many respects, beause of some unusual angles, this is the most difficult car we have discussed so far.

Start by removing the trucks and couplers in the usual way. Remember to cut off the tang that holds the stock couplers to the trucks. Now remove the floor from under the body casting.

The ARISTO Covered Hopper Coupler Height Adapter

Note that the end of this car includes some angled floors making body mounting of couplers a bit tricky. The spacer that I came up with compensates for the angles and puts the Kadees at just the right height. While I was at it, I thought it might be an interesting challenge to try to include some aspects of an I beam in the casting.

This picture shows the final product from the side, and you can see the lower lip of the I beam shape that I managed to make. Here's another image showing the adapter from the bottom. And lastly, another image showing the adapter from the end.

Needless to say, I copied this part in resin castings and, when mounted on the underside of the car floor it looks like this.

I attach these to the car floor with 2-56 flat head machine screws and some epoxy glue. I then use 4/40 round head machine screws to attach the Kadee draft gear.

When you have the adapters attached, paint them flat black and then assemble the Kadees.

After reassembling the car floor to the body, here's what the final assembly looks like after you have put the car back together.

Testing for Correct Height

Reinstall the trucks and test for correct coupler height with a gauge as with the other cars we have mentioned.

ADDING BODY MOUNTED KADEES TO ARISTO STREAMLINED PASSENGER CARS - BOTH SHORT AND LONG

This section of this article is still under construction but will be finished soon, so check back for updates after the national convention.

ADDING BODY MOUNTED KADEES TO ARISTO HEAVYWEIGHT PASSENGER CARS

This section of this article is still under construction but will be finished soon, so check back for updates after the national convention.

I will gladly furnish copies of my coupler height adapters to anyone who wishes to copy them for themselves and will sell limited quantities to anyone who has neither the time or the skill to copy them for themselves.

Well that's all for this session. I hope this article gives you enough information to try a couple of these projects for yourself.

If you have any additions, corrections, or comments on the content of this , or any of my articles, please send them to me at This email address is being protected from spambots. You need JavaScript enabled to view it..

Thanks for your attention. Now get busy!

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