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Installing a Kadee #5 Coupler Box and Coupler

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  • Member since
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  • From: Chamberlain, ME
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Installing a Kadee #5 Coupler Box and Coupler
Posted by G Paine on Wednesday, July 13, 2011 1:09 PM

In a recent post, I started describling how to convert a Tyco or similar car from truck mounted couplers to body mounted couplers. In that post, part 1, I described installing removing the old post mounted trucks and replacing them with new screw mounted trucks.

Some older horn-hook couplers were installed in a narrow body mounted coupler box that would not fit a Kadee 5, just cut and file away the old box and install a new one as described here.

Here, I will describe installing a Kadee #5 coupler box and coupler. Just to get our nomenclature straight, this is a picture from the Kadee coupler instructions with the parts named

The first thing to do after the new trucks are installed is to file or cut away anything that sticks out and would interfere with a flat area for coupler box installation. Once this is done, measure the height of the underside of the car to see if it is correct for the coupler box installation using the back side Kadee #205 coupler height gage.

The top of the gage should just fit under the end of the car.

If the gage hits the car, it will have to be raised or parts of the car body will have to be cut away to make room at the correct height. Kadee makes fiber washers: #208 for 0.015" thick (red)and #209 for 0.010 thick (gray). Remove the trucks and place a washer or washers between the truck and bolster. A third alternative is to use a #42 Overset Shank coupler where the coupler head is lower than a standard #5.

In my case, the car was a bit too high. I used scrap styrene to measure the gap, starting with 0.010" thick and working up in thickness until the styrene would not fit the gap.

Select the next thinner styrene and cut two mounting pads slightly larger then the dimensions of the Kadee coupler box cover. Glue the mounting pads to the underside of the car and on the car centerline. The outer end of the pad should be flush with the end of the car. You should have the body of the car mounted when instaling this part. 

In the above picture, I have shown a coupler cover on the right pad, DO NOT glue the covers yet.

Next, mark a centerline on the coupler pad; the line should be the centerline of the car. Then place the coupler box cover over the mounting pad and mark the center of the mounting hole. Note the small lip on the end of the cover, this lip goes on the outer end of the mounting pad and assures the coupler box is mounted correctly in the lengthwise dimension.

Drill a hole in the coupler mounting pad using a #43 drill and tap it with a 2-56 tap. Kadee sells a kit #246 that includes the 2-56 tap, the #43 tap drill and a #50 clearence drill (not used for this installation).

Glue the coupler lids to the mounting pads making sure that the hole in the lid is centered over the mounting hole on the pad. If you are using a viscous glue,be careful not to get glue down the mounting hole.

Then a quick trip to the paint shop to cover up all the white styrene; I use Floquil Roof Brown. Put all the screws in, both coupler and truck, so the heads are painted and paint does not get into the threads.

Check that you have all the parts for the coupler. Inspect the centering spring for correct alignment. Note the misaligned leaf spring on the left side od the photo. Correct this by gently pulling the leaf so it pops into the correct position. The coupler will not work correctly if the spring leafs are not in the proper position.

I lightly spray paint all my couplers with Floquil Roof Brown when I buy them, to give them a rusted look. I leave the coupler trip pins on, many others remove them - there has been a recent lengthy discussion about this. Follow you personal preference on this. After painting, I puff a small amount of Kadee #231 Greas-em Lubricant on the coupler shank and burnish it with the end of a hobby file. This is a powered graphite dry lube.

Install the couplers and trucks. Check the coupler height with the Kadee gage. Adjust the coupler trip pin if it is too low. A low trip pin may hit on turnouts, and grade crossings causing a derailment or other problems.

Add some weathering, if you want and put the the car into service on your layout.

George In Midcoast Maine, 'bout halfway up the Rockland branch

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Posted by IRONROOSTER on Wednesday, July 13, 2011 1:17 PM

Nice tutorial. 

You might add that Kadee makes a trip pin adjustment tool  I find it very easy to use.



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Posted by jeffrey-wimberly on Wednesday, July 13, 2011 1:34 PM

I've done that with some older trainset cars that had truck mounted couplers. I found very quickly that it's very important to put a shim between the car body and the coupler box. If not the coupler will be too high. Being that I don't have sheet styrene laying around I use whatever is laying around, even card stock. Many times I use old coupler box covers from junk cars. I had one car (boxcar or reefer) that had what was for lack of better name, an abbreviated frame. The frame ran from one bolster to the other bolster leaving an open gap at each end of the cars underside. This presented a problem as there was nothing to attach a coupler box to. I cut a couple of pieces of scrap plastic to fill in the gaps and attached them to the existing frame with more scrap plastic bridging the pieces. I didn't want it getting any ideas about going anywhere so I used JB Weld to glue them together. This gave me a surface to mount the coupler boxes to and the problem was solved. I ended up using two shims on each one as the bottom of the car was slightly recessed.

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Posted by Catt on Thursday, July 14, 2011 9:38 AM

I no longer replace the trucks on train set cars.I bought one of the truck reamers and use it on any truck that does not free roll.I have discovered that these trucks can be extremely free rolling even with the origonal plastic wheel sets though I do prefer metal wheels for looks and staying clean longer.

As for body mounting the couplers I find the OP is dead on with his mounting method.Though when it comes to shimming the couplers I will put the car on the track and check to see if it sets to high itself.If that is the case I file down the bolster to get the correct car height and coupler alignment.

Johnathan(Catt) Edwards  (My railroad's logo) Co-founder of The North American Rail Alliance A purrveyer of Possible Actualities
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Posted by rrinker on Thursday, July 14, 2011 2:26 PM

 Take note of the pictures of the springs. That's a common failure mode for the #5-type bronze pan spring. If you have a coupler that spring back from one side but not the other, take a look - I'll bet your spring looks liek the one on the right.



Modeling the Reading Railroad in the 1950's


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Posted by joe323 on Thursday, July 14, 2011 2:29 PM

Where do you get the tiny screw that most body mount couplers need?  Kadee does not include it in the envelope.


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Posted by cf-7 on Thursday, July 14, 2011 4:15 PM


Where do you get the tiny screw that most body mount couplers need?  Kadee does not include it in the envelope.


I always use the Kadee part number 256.  It is a 2/56 nylon screw.


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Posted by G Paine on Friday, July 15, 2011 2:19 PM

Walthers sells a variety of small screws, this is a search on 2-56 screw

If you think you will be needing a lot of these screws, ask at a good, old fashioned hardware store (not one of those all-computer boxbox ones). You may be able to order a box of 100 at a real good price compared to the bag of a few at hobby shop prices.

George In Midcoast Maine, 'bout halfway up the Rockland branch

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