Kadee Body Mounts for Aristo Heavyweights

Kadee makes specialized components for body mounting Kadees on these cars.

Initially I just threw the truck mounted couplers on these cars, and I immediately had uncoupling problems behind my new E8. The couplers just rode over each other. (note Aristo couplers have a "shelf" under the coupler that prevents overriding, no wonder)

What helps make this overriding much worse is that the design of the Aristo 3 axle truck is such that pressure/weight from the body is not evenly distributed fore and aft since the pivot point is not in the center of the truck. This causes the truck to be way out of level. Also, the long coupler tang has too much leverage against the truck and it's springs. 

The result is excessive travel up and down of the coupler.

So I decided to try the Kadee body mounting system, even though I have some sharper than hoped for vertical transitions.

(Being body mounted, the coupler "attitude" is not from the coupler tang on the truck, but the overall attitude of the car, which should be worse on a long car over vertical transitions)

Initially, I only changed the first car in my train (RPO) with the Kadee-recommended mounting. The results seemed OK, but there was no close coupling.

Then Ted Doskaris developed the technique for close coupling with centerset couplers.

Finally, I tried sort of a hybrid, getting pretty much the same close coupling, but utilizing the Kadee spacers, instead of fabricating spacers.

The bottom line, correctly body mounting Kadees was worth it, but it was not just adding the couplers and "go", changing over to body mounts caused other issues that needed to be addressed on my tight curves and my "S" curves.

The Kadee solution:

The Kadee parts consist of:

The way it works, there is a square recess at the end of the car. You cut the old coupler tang off, screw the bracket to the coupler housing and then to the shim, and the whole works is glued into this square recess.

Unfortunately, the RPO, full baggage, and the platform end of the observation car, have no recess. (Thanks a lot Aristo!).

    • You also need to notch one side of the shim, because you need clearance there too!
    • To mark what to cut out, measure from the leading edge of the diaphragm back to the back of the shim, exactly 2 inches.
    • Then mark the crossmember with the angled end of the shim, and then cut it away, I used a carbide bit on a dremel.
    • Notch the other end of the shim to clear the end of the car, and the whole thing sits in place. Kadee says to glue, but use a number 44 drill (.086") through the two holes and use Kadee 2-56 screws and nuts to secure it. These are the long ones that used to come with Kadee 830's. Newer 830 and 906 come with self threading screws.

The picture below shows the assembly in place:


And, instead of gluing, I was able to use screws, you can see where they come up through the floor inside. They are the two screws in the center in the picture below.

This works ok, but I think it is not the best solution.

    • You don't really need the flex bracket for 8 foot diameter and above
    • It does not provide close coupling
    • The "slack action" coupler is really a poor choice for passenger cars and close coupling because of the in and out movement of the coupler forces you to increase car to car spacing.

Better body mount solution:

My friend Ted did find a way to use the recess for a center-mount Kadee and without the slack action. CLICK HERE to see Ted's vignette. He also solved the issue of the observation car that basically had no way to support the coupler.

But I wanted to see if there was a way to use the spacer block #881 with a fixed coupler mount, and not cut shims myself.

From my previous experience, the 830/906 is not a solution if you want close coupling, the coupler box would hit the truck, not to mention the unwanted slack action makes it pretty much impossible.

I found that a center-set coupler was pretty good spacing, height and setback in an 831 housing.

Here's a picture of it test fit in a car: (this is NOT the final configuration of the mounting screws)

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 Basically, the center of the trip pin should be close to even with the end of the diaphragm: (this picture does not exactly sight down the face of the diaphragm)

 20190907 144544

Checking with Kadee gauge: pretty darn close!


So the mount is pretty simple, below is the mockup (note the screw at a slight angle) Using some of my cache of Kadee 2-56 screws and nuts, the 881 shim and the stock coupler are bolted together. The second screw keeps the gearbox from shifting, increases strength, especially since the screw in the center is in the large hole of the gearbox, not a tight fit.



Above: Drill the hole from the outside while the center screw is pretty tight and push the gearbox "right" on the Kadee "block", this will give you the nice close coupling. This step has to be done because the other hole is too large for the 2-56 screw.



I decided to put the screw heads inside the block, so you have to mill down the inside a bit so the screw head is flush with the top of the block:

Look carefully, I only milled down half of the center "boss", so if you wanted to use a screw to secure the mount to the car, you can use the larger hole.

2-56 screws and nuts are used here.



To mount the assembly, I just used a high quality ACC glue to put in place, a bead of glue around the rim seems to be plenty strong.

So, mission accomplished, use a stock Kadee adapter block, with 2 simple mods and get correct coupler height, close coupling and no interference with the 3 axle trucks.

(or so I thought, the back side of the shim needs a 45 degree bevel to clear the truck. See the section on "Adding Truck Clearance".


Observation cars:


For the observation car, I used a "T" bracket just like Ted did, but since I cut off my plastic bosses and put 2 screws through the T bracket, the ones I added in my "clearance" procedure.

I just put holes in the bracket to match my screws, which are exactly 47.5 mm apart, then my 3mm truss head screws will go through the bracket.



I know the projection of the coupler here is more than needed, and will probably move it back in the future, but since this is the end that couples to the loco, it does not look bad. I want to revisit this after running for a while, and also maybe shim between the bracket and the platform floor to get things exactly level.

I used 2 of the flat shims that come with the #881 package.

Alignment came out well:






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