Aristo Heavyweight Passenger Car & Body Mount Kadee 907s

Aristo Heavyweight Passenger Car & Body Mount Kadee 907s
Ted Doskaris
October 5, 2015
Rev GE-A

October 6,2015
Rev GE-B1 Added picture of factory cars' truck mount coupler & car Cylinder, etc. R&R

March 7, 2017
Rev GE-C  Added info. with respect to 3 axle trucks

April 6, 2017
Rev GE-D  Major update: Added remaining heavyweight car types

April 9, 2017
Rev GE-D1 Corrected value in note below RPO & Baggage car spacer dimensional drawing

September 11, 2019
Rev GE-E  Added Kadee coupler projection measurement illustrations

November 8, 2019
Rev GE-F  Washer requirements for mounting trucks clarified

November 13, 2019
Rev GE-G Added appendices C-E for: Vestibule R&R; Backwards Lavatory Commode; Step and Reproduction


An example Aristo-Craft Dining car fitted with body mounted Kadee 907 centerset couplers is shown below.





Heavyweight Car Types
Preliminary Preparation
Required Spacer Plates
Spacer for Car with Plain End
Spacer & Shim for Car with Vestibule End
Spacer & "T" Plate for Car with Platform End
Appendix A - Aristo 3 Axle Truck Wheel Gauge
Appendix B - Adding Weight

Appendix C - Vestibule R & R Method
Appendix D - Lavatory Commode
Appendix E - Step Reproduction




The Aristo-Craft Heavyweight passenger car is factory equipped with truck mounted Aristo knuckle couplers. 

Shown below are example like kind cars having different factory coupler projections. The more the projection the farther distance the cars are from one another when coupled together.  Replacing these truck mount couplers with body mount Kadee couplers, also, brings the cars closer together for much more realism.


The factory couplers are done away with - being replaced with body mounted Kadee centerset type couplers.  Accordingly, this "vignette" describes and illustrates body mounting Kadee 907 (or older Kadee 789) center set coupler assemblies on Aristo-Craft Heavyweight cars.  (The examples shown herein are cars having 3 axle trucks.  Cars having 2 axle trucks would not impact using these type Kadees.)

The coupler box mounting location is chosen so cars can operate down to 8 foot diameter track whilst, also, being compatible for "mix and match" operation when coupled to locos like the Aristo E8/9 as well as Aristo Streamliner, Smoothside, and USA Trains passenger cars - providing those had been equipped with body mounted Kadee centerset coupler assemblies as described in their respective "vignettes".

I strive for train operation down to 8 foot diameter track (since this size provides access to a rail yard) and for assured operation on 10 foot diameter track that is used in some parts of the overall main layout.  

The Aristo-Craft brand track identified as being 8 foot diameter, when measured, is actually 1 and 5/8 inch narrower!  This diameter will establish how close cars and locos can be without touching or  binding, thus, determining where body mount couplers are to be located. The trade-off is: the tighter the curve track, the farther apart coupled cars will be noticeable on straight track.


Shown below are example Aristo "head end" type heavyweight baggage & RPO cars having been equipped with body mounted Kadee 789 center set couplers.

Shown below are the cars having been equipped with body mounted newer type Kadee 907 center set couplers with chosen coupler mounting location so as to be compatible when operated on 8 foot diameter track.

As shown above, note the distance spacing between coupled cars that resulted from the coupler box mounting location that was established so cars would not bind on 8 foot diameter track yet be as close as possible.

Shown below is another example that depicts an Aristo heavyweight observation car coupled to an Aristo E8 loco.

Note how close the car & loco diaphragms are when their couplers are in tension.  They would be closer and virtually touch if the train were to be backing up.  This worst case proximity establishes where the body mount couplers are to be located on car type having a vestibule end.

Similarly, the observation car's platform coupler mount proximity was establish as shown below.

Shown below is the resultant relationship of the platform car end coupled with the plain end RPO car.


Heavyweight Car Types

Aristo-Craft heavyweight cars include "head end" types of Baggage, Railway Post Office (RPO), and Combination (Combine).  Other heavyweight car types include the Coach, Diner, Pullman (sleeper) and Observation.

As previously indicated, the ends of these cars can differ, and, as such, impact what is done for body mounting couplers.

Accordingly, the detail that characterizes car ends can be described as follows:
(1) Plain (applicable to RPO, Baggage car)
(2) Vestibule (applicable to Combine, Coach, Pullman, and one end of the Observation car)
(3) Platform (applicable to the other end [rear] of the Observation car)

The Illustration below depicts examples of the 3 different car ends with characteristic detail.




Preliminary Preparation:

In order to accommodate an installed body mount coupler, two things should first be done:

(1) Remove Truck Mount Coupler & its Tang.

Though, if careful, removing the truck's tang can be done without removing the truck, it's much easier and safer to temporarily remove the trucks so the cut can be done on a work bench.

Note:  For production run differences with respect to 3 axle trucks, including fixing possible electrical wiring issues whilst done with trucks removed, see vignette, title:
Aristo-Craft Heavyweight Passenger Car 3 Axle Truck Types.

Next to be described is an example late version heavyweight car with 3 axle trucks having a fulcrum rib across its bolster mid point as shown in the above illustration.
Advisory:  Shown below is a metal washer to be placed over the chassis post on a late version car that the truck pivots on, but a Nylon type washer (or washer stack) of 0.060 to 0.070 inch thick is preferable to use. Older version cars having trucks without the fulcrum rib will use a different washer thickness and, also, use a thin washer over the chassis sliding slot post. Washer requirement are described in "Mitigation Fixes" for all version cars in same vignette previously referenced.


(2)  Notch the Diaphragm.

The car end diaphragms need to be notched at the bottom so as to allow the installed body mount Kadee coupler to swing freely and completely side to side.  This is most important for the bulkier Kadee 907 compared to the older 789.  Some production run Heavyweight cars have  rigid plastic diaphragms and some have flexible diaphragms.
The notch dimensions are Illustrated below with an example RPO car; however, it's the same for all car end types having a diaphragm.

Note:  Cars with plastic diaphragms can be cut using a razor saw, small pair of cutters, and then finished with a file whilst later production run cars having flexible diaphragms can be cut using a sharp pair of scissors)

The illustration below shows how an installed coupler can freely move side to side with sufficient diaphragm clearance provided.


Illustrated below is another example car (Diner) with plastic diaphragm




Required Spacer Plates:

A spacer plate is required  for mounting couplers in order to attain proper coupler alignment with the Kadee 980 track height gauge.  There are 3 different ones depending on car end detail.  Each one will be described separately.

The spacer material used is black ABS plastic that can be obtained inexpensively from


They offer several nominal size widths (actually slight thinner when measured that can be advantages) and will cut it to as little as 1 inch wide in 3 to 4 foot long strips.

Spacer for Car with Plain End
(Applicable to RPO, Baggage car)

Spacer Drawing for plain end car shown below.

The drawing dimensions shown above were determined for car operation down to 8 foot diameter on Aristo brand curve track.  Layout "S" bends are to have a straight track section the length of the longest car between opposing directional transitions.  If a layout has 10 foot minimum diameter track, then the coupler assembly could be moved further in from the end sill of the car.  In this case I would anticipate the "L"  dimension distance could be reduced by 0.075 inch (from 0.300 inch to 0.225 inch).  Likewise, the group of two holes would be moved down by 0.075 inch (from 0.425 inch to 0.500 inch).  Hole spacing would remain the same at 0.450 inch.  The distance between like kind coupled cars would reduced by 0.150 inch.


Required Mounting Location:

Shown below is where two holes are to be drilled and tapped into the car floor.

Note that the example car is equipped with 3 axle trucks.
After holes are drilled, a # 2-56 tap is used for the long length 2-56 screws needed to mount the box with spacer:


Mounting Coupler Box:

An older style Kadee 789 coupler assembly profiled with the spacer is shown below.

Both older Kadee 789 and newer Kadee 907 assemblies will work, however, I chose to use the newer Kadee 907 coupler assembly as shown below.   I found that coupler holding retention to be better with the Kadee 907 when operating a long heavy train on my layout with its grades and curves.


Illustrated below is the mounting of a Kadee 907 assembly.
A #2-56 screw,1 inch long, is used in the front and 0.7 inch long screw is used in the tail.
(Shown below example - Allan head at front & cut-off Kadee stainless at tail)



Spacer & Shim for Car with Vestibule End
(Applicable to Combine, Coach, Pullman, and one end of the Observation car)

An example observation car is shown below.

The vestibule underside includes a pocket in which to place a shim that will also serve as a template for accurately drilling holes for mounting the Kadee box.  Accordingly, the shim is sized to fit within the pocked having minimal surround clearance.


Spacer & Shim Drawing for Vestibule end car shown below

The drawing dimensions shown above were determined for car operation down to 8 foot diameter on Aristo Brand curve track.  Layout "S" bends are to have a straight tack section the length of the longest car between opposing directional transitions.  If a layout has 10 foot minimum diameter track, then the coupler assembly could be moved further in from the end sill of the car.  In this case I would anticipate the "L"  dimension distance could be reduced by 0.075 inch for spacer (from 0.225 to 0.150 inch).  Likewise, the group of two holes would be moved down by 0.075 inch for both spacer & shim (spacer from 0.425 to 0.500 inch; shim from 0.200 to 0.275 inch).  Hole spacing would remain the same at 0.450 inch for both.  The distance between like kind coupled cars would reduced by 0.150 inch.

Shown below is an example spacer and shim.

Shown below is the shim being installed within the pocket and using it as a drilling template. The shim with the two predrilled pilot holes closest to one of its edges, when installed, should face the car's end sill.


Mounting Coupler Box:
It's best to glue the shim within the vestibule pocket as previously illustrated.  If not glued, then the shim must be firmly held down whilst drilling & tapping and then the coupler box with spacer must be held down when fastening it.  If this is not done the shim could lift off the pocket when fastening the coupler box.

Note:  The Kadee coupler box front mounting screw length should be not less than 0.9 inch.  A box of inconspicuous black # 2-56 by 1.0 inch long screws can be obtained via Amazon.



Resultant measurements after installation of a body mounted Kadee assembly are shown in the following illustrations:

The Aristo heavyweight car example shown below has a rigid plastic diaphragm that is about 0.3 inch thick. Sometimes the diaphragm is loosely fitted and may need to be glued.


Because later production Aristo heavyweight cars were factory equipped with flexible diaphragms, the following measurement would be more appropriate:





Spacer & "T" Plate for Car with Platform End
(Applicable to the rear of the Observation car)

First, some preliminary information:

The Aristo heavyweight observation car's rear platform has an intrinsic downward warp owing to its attachment design to the main floor.

The platform with downward warp is not only displeasing to look at but unacceptable for body mounting a coupler due to its warp and flexibility.  However, may folks may not be concerned with body mounting a coupler on the rear of the observation car being it's normally the last car on the train.

That said, the prototype Napa Valley Wine Train that operates in California, indeed, has two observation platform cars, one at each end of the train.  They do this so the two back to back MLW (ALCO) FPA-4 cowl type locos can uncouple from one end of the train and run past it on a siding and couple to the other end of the train for the return trip, thereby, not requiring a large loop around track or Wye type turnout for directional change.

Since I have the Aristo Napa Valley Train with two observation cars, I chose to body mount the Kadee 907 coupler assembly on the rear of these cars by employing a rigid "T" Plate structure to straighten the platform in conjunction with using a spacer.

The Kadee coupler assembly is to be mounted on the leg of a modified "T" plate (described later) with spacer sandwiched between it and the plate.

Spacer used on "T" Plate:
Spacer drawing for platform end car shown below

The drawing dimensions shown above were determined for car operation down to 8 foot diameter on Aristo brand curve track.  Layout "S" bends are to have a straight tack section the length of the longest car between opposing directional transitions.

The "T" Plate:
The "T" plate with coupler assembly will then be mounted on the underside of the platform end of the car as shown below.

The T part of plate includes cutout notches that serve to "lock-in" the mounted plate so it won't move laterally. ("T" Plate modifications will be described later.)

Note: If not choosing to body mount a coupler, the modified "T" Plate by itself can be used to straighten the platform.

"T" Plate Modifications:
The "T" Plate is modified from a common construction metal fastener that can be obtained from a hardware store or mail order, namely the Stanley - National No. 116 that is 3 inch by 3 inch by 0.070 inch thick.

For how to modify the "T" plate and how it will fit on the car floor, see the following Illustrations:

The cardboard template is useful for establishing the shape of the cutouts since it can be made by "trial & error" if need be until it fits the car floor bosses as shown.  Be sure the two cutouts are at the same depth at 0.035 inch.


Mounting "T" Plate with Coupler Assy:
Car preparation for mounting the "T" plate requires drilling & tapping a precisely located hole in the car floor using the plate as a template.  The location of the mounting hole in both "T" plate and floor was chosen to act as a leverage point.  As the mounting screw is progressively tightened down, the stiff metal leg of the plate forces the flexible platform to become straight whilst at the same time establishing the correct coupler height from the rail head.

The "T" Plate with coupler is mounted using only one # 2-56 by 0.5 inch long screw with lock washer as Illustrated below.




SP 9 Car Daylight Train with mix &  match cars on outdoor Layout



Appendix A - Aristo 3 Axle Truck Wheel Gauge:

Based on operation on my layout with the long wheel base 3 axle trucks, traversing Aristo Wide Radius turnouts may be problematic.

I found it behooving to adjust the gauge for back to back spacing of the wheels to minimum NMRA spec. to ameliorate operational ill effects.

Shown below is an example method for gauging the Aristo wheels.  The wheel with plastic insulated hub need only be adjusted.

Lubrication of the axle tips can be done before reinstalling the axle/wheel sets.  When installing the wheels, be sure to pay attention to which way the insulated hub is facing - whereby it's tip should go into the side frame bushing that does not have a wire connected to it.


A heads up!
Whilst operating one of the Wine Train cars on the layout, smoke billowed out from under one of its trucks!  The cause was an electrical short circuit between one of its insulated metal wheels and axle due to excess residue plating material - shown below.




Appendix B - Adding Weight:

The weight of the Aristo Heavyweight cars that include all but the RPO and Baggage cars is adequate, though maybe they could be increased by a half pound depending if operation with a long train is on tight curves.
An example Dining car fitted with Kadee 907 body mount couplers without any additional weight is shown below.


However, weight should be added to the relatively lighter RPO and Baggage cars to avoid "string lining" on a layout with tighter radius curve tracks when operating these lighter weight plastic Aristo Heavyweight car in a consist of other physically heavier metal passenger cars (e.g. Aristo Streamliner, Smoothside or USA Trains car).

Two 8 inch long, 1/2 inch square, steel bar stock can be used.

This will add about  1.1 pound.

The additional weight is best placed within the underbelly of the car for low center of gravity.
The added weight will fit virtually out of view between the car's underbelly ribbing.

A little more "how to" detail is shown below.



Shown below is the weight of an example Heavyweight Baggage car before weight was added.

Shown below is the weight of the same Heavyweight Baggage car after weight was added.

Shown below is the weight of an example Heavyweight RPO car after weight was added.

As can be seen, the weight of a plastic Aristo Heavyweight car (admittedly a misnomer) is increased from about 5 to 6 pounds, whilst dramatically establishing a low roll center due to the low proximity of the added weight.



Appendix C - Vestibule R & R Method

Illustrated below is an example of how to remove Aristo's Heavyweight car end bulkhead and vestibule subassembly.



Reinstalling the Vestibule:

Included in the illustrated below are suggestions for reinstalling the vestibule subassembly.
Note: Placing and then seating the vestibule within the car body's side slots may need some help by using careful, repetitive back & forth force at its middle and sides as shown in the illustration.



Appendix D - Lavatory Commode

It has been noticed by many folks that the commode and /or commode lid in heavyweight cars can be oriented backwards during factory assembly. Normally, you can't see this from the outside of the car, but if there is a reason to access the car's interior, the opportunity is presented to correct this.

Illustrated below are excerpts from Aristo Exploded Parts Diagrams for Coach, Diner, Observation, Combine and Doodlebug that show lavatory components. Only the observation car depicts the backwards orientation of the commode!

For one of my cars, the lavatory wall had been dislodged and rattled around within, so during the processes of correcting it, the commode was discovered to be in backwards, too, - illustrated below. (Of necessity, the vestibule subassembly had to be removed to expose the car's end interior as previously described in Appendix C.)


Testing car's interior lamps:

With the end of a car exposed, the interior lamps can been seen, so they can be tested to see if all will light. An example test method is illustrated below:




Appendix E - Step Reproduction

One of my cars, obtain used, had a missing vestibule step.


Replacement factory steps can be difficult to obtain, so at the time I dealt with it, I did not realize Gilbert Lacroix's GLX Scale Models Inc. has a 3-D printed replica listed for the Aristo Doodlebug - which shares some parts with the heavyweight car; however, looking at the picture of Gilbert's 3-D printed step shows it has a tongue on each of its sides, whereas, the step in my cars have pegs.

The tongues or pegs are intended to mate with the vestibule and end bulkhead corresponding groves or holes.
Note: Because the Doodlebug is a product adapted from the heavyweight car, the step would be expected to be the same for the heavyweight cars.

Illustrated below is an Aristo factory step from the opposite side of the vestibule that was removed for examination so a replica could be made:


It seems easier to purchase the Doodlebug step from Gilbert Lacroix, and modify it if need be for the heavyweight car, but if choosing to make one, illustrated below are measurements of the step.

Note: The other side of a car's vestibule will have "mirrored" sides of the step with respect to its pegs and notch serving as a key used to mount it. This means for a car having a vestibule at each end, there would be 4 total steps with 2 steps mirrored.

Illustrated below is the measured step put to practice.
The step components can be made from a sheet of ABS plastic of about 0.060 to 0.090 thick obtainable from TAP Plastics.


Illustrated below is how a factory step relates to the vestibule and end bulkhead with its notch and pegs.

Unlike shown above, to remove or install a step, only the end bulkhead needs to be temporally unfastened and tilted outward.
For simplicity, the replacement step was neither made with one side having a cutout for truck tang clearance, nor with flared bottoms nor with mounting pegs, consequently, it was CA glued only to the vestibule, not to the end bulkhead. This, also, allowed for the step to be better horizontally aligned given the poor build quality of the particular Aristo first version car it was installed on - illustrated below.

Note how the factory steps have cutouts to clear the factory truck tang. If using body mount couplers, the cutouts can be plugged with a glued on piece of plastic for prototypical appearance.



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