Aristo Flat & Gondola Car

Lowered, Weighted, and

Fitted with Kadee Centerset Couplers

Aristo Flat & Gondola Car - Lowered, Weighted, and Fitted with Kadee Centerset Couplers
Ted Doskaris
September 1, 2011
Rev. GE-A

September 10, 2011
Rev. GE-B, added material

September 23, 2011
Rev. GE-C, added alternative solid aux. weights & bulkhead end car type

November 18, 2012
Rev. GE-D
Added Aristo Gondola car Appendix A; Bracket drawing update of Oct. 19, 2012 includes threaded hole at more exact location

November 19, 2012
Rev. GE-E, added bracket installation picture to Gondola Appendix A

December 1, 2012
Rev. GE-F
Replaced Appendix A redundant gondola picture with bolster notch picture

December 19, 2022
Rev. GE-G
Added custom lengthened Gondola; Added Table of Contents

Contents:

The Aristo Flat Car
Lowering the Aristo Flat car
Modifying a Truck To Lower the Car
Floor Modifications Needed - original "tall" Aristo floor type
Mounting Kadee 907 Centerset Coupler Assemblies
Notching the End bulkheads
Adding Weight to the Flat car
Aristo Flat Car Variations
Operational Results
Videos
Appendix A - The Aristo 40 ft. Gondola - Lowered
Gondola Disassembly
Gondola Car Body Modifications
Re-assembly of car body
Coupler Assembly Installation
Truck Installation
Adding Weights
Measured Result of Lowered Aristo Gondola
Custom Lengthened 52 ft. Gondola

The Aristo Flat Car

The Aristo-Craft flat car is fairly light in weight, and if you have older versions like I do (before Aristo started making the lowered floors for its 40 freight cars standard),  the car sits way too high from the rail head.

Since I have been retrofitting rolling stock with Kadee body mounted centerset type couplers, I decided to resolve the flat car height and weight issues at the same time; after all, if you have to determine and establish the proper coupler to railhead distance when mounting centerset Kadee couplers, then it's compelling to address the height issue at the same time.

Shown below is a comparison of an unmodified Aristo flat car on the left and the lowered car (by 0.200 inch) after modifications on the right.  Lowering the car has advantages other than just prototype aesthetics.  As the car weight becomes closer the rails it helps lessen the tendency for string-lining it around curve tracks.

 
Shown below is a Union Pacific Flat car on the left before I lowered it. The Southern Pacific lowered Flat car is on the right.


As to the weight issue, shown below is an example of a standard Aristo Union Pacific 40 foot flat car, equipped with Aristo ART-29111B metal wheels (before being modified) that measures about 1.7 pounds.


In comparison, an Aristo 40 foot box car with the same metal wheels weighs about 2.75 pounds.


That's about a whole pound more for the box car and enough to prevent "string-lining" the car around curves (depending on one's  layout parameters) when operated on the front of a long, heavy train consist.  In my case, a 270 degree 10 foot diameter loop back is critical for such a train.

Shown below is a lowered and fully weighted Aristo flat car fitted with Kadee 907 centerset coupler assemblies on the layout loop back being pulled behind the locos on a 62 car train.


The weights added to the flat car are out of view and the car's total weight exceeds that of an Aristo box car equipped with metal wheels.


Now for the how to's:

Lowering the Aristo Flat car

If you have a newer production run Aristo Flat car with the factory lowered floor, you won't have to lower it  more so unless you are striving for prototypical perfection as measured from the rail head with respect to car's floor surface.

The picture below compares the truck bolster area of the older production run (non lowered) Aristo 40 foot freight car floor with the newer production run lowered floor.  The Aristo NON lowered floor is on the top, and the newer Aristo lowered floor is on the bottom.

Looking at the above picture, it can be seen that the older NON lowered floor has a more pronounced bolster height and adjacent ribbing .  As it turns out, the larger volume within the older floor's bolster can be used to advantage for adding weight therein. This will be discussed later.

Shown below is a view of the floor bolster cavity with the simulated wood flooring detached - in this example a first generation Aristo Korean or early Chinese factory made with yellow colored floor before gluing it in place was adopted.


The following information applies to those cars that have the older Aristo (NON lowered) floors.

Preface

Prior methods folks used to lower cars included cutting out the floor bolsters, trimming them down and then reinstalling them (using glue) or fabricating new ones (maybe using home made molds) to make shallower bolsters to replace the cut out ones.  It would seem such methods require a high skill level with much time and effort to bring to fruition.

A simpler way of being able to lower the Flat car (and others) without using Aristo's newer lowered floor assembly is to fit the car with trucks that can serve to lower the car .  (BTW, this approach, also, applies to other Aristo 40 foot freight cars, like the Gondola, Box car, Stock car, and Reefer car.)
When using trucks to lower the Aristo 40 foot freight cars, both trucks and car floor have to be modified to coherently work together.

Modifying a Truck To Lower the Car
 
The truck I used is the USA Trains (USAT) brand plastic Bettendorf truck, no. 2033.  An alternative similar truck that could be used is the AML brand metal Bettendorf truck version that resembles the USAT plastic one, but when doing modifications metal is more difficult to work with than plastic.
 
I first used the USAT modified truck method for lowering the Aristo covered hopper car.
See article, "Aristo Covered hopper, Lowering & Kadee Coupler Installation" hosted for me on Greg E's web site.


Since these type trucks do not employ actual working springs (like the Aristo ones do) their design allows lowering the bolster within the truck assembly without having any external visual affect; thus, the car will be lowered when these modified trucks are attached to the car.  Moreover, as a side benefit, the wheel base of the USAT truck is more prototypical than the Aristo one being it scales out to the more common 5 foot 6 inch wheel base model, whereas, Aristo's truck scales out larger to 5 foot 8 inches.

Depicted below are areas of the USAT Bettendorf truck that are modified to lower its bolster 0.210 inch within the truck as well as what else needs to be done for operational fitment.


As to metal wheels, I used the Aristo ART-29111B since I already had them, but if metal wheels are to be  acquired, the USAT wheels are preferable since they are about 0.040 inch smaller in diameter at the tread than Aristo's and will serve to lower the car an additional amount by half that (e.g. 0.020 inch).

As shown below, the USAT lowered truck with Aristo ART-29111B wheels (I painted them black) is out of level (slightly taller) than the USAT lowered truck on the right with its USAT metal wheels.
 

To lower the car by approximately 0.200 inch, the USAT truck bolster is to be lowered within its side frames by 0.210 inch. (The car / trucks could be lowered an additional small amount, but complications arise to deal with, such as removing the shallow ribbing on the underside of the floor where wheel flanges would then interfere as the trucks pivot.)

Shown below is a dimensional drawing of the USAT truck modifications.


Shown below are pictures that further illustrate areas of the truck bolster as it was being modified.

The sides of the bolster are cut down (along with the side frame pockets) so the bolster will assume a lowered position when the truck is reassembled.  Also, the rib at the base of the bolster is notched so the bolster will fully seat in the side frame pocket.



Both inner ribs are to be removed flush with the surrounding surface.  One of them is shown being cut away with a razor saw.  This allows the mounted truck to freely pivot.


The truck's tang must be removed so as not to interfere with the installed axle.


The side fame modifications are illustrated in the following pictures:


Material from the side frame pocket is to be removed so that 0.245 inch remains.

An Xacto no. 235 Razor saw can be used to make both vertical and horizontal cuts to remove the excess pocket section.


Comments:
In the event either the side frame pocket or bolster side were cut a bit too short, it is to be appreciated that the longer of the two will dictate the overall assembled result of the truck.  For example, if the side frame pocket were to be less than its targeted 0.245 inch height but the bolster side height is at its targeted 0.345 height, the assembled truck will be OK.  Likewise, if the bolster side height were to be less than its targeted 0.345 inch height but the side frame is at its targeted 0.245 inch height, the assembled truck will be OK.  This, of course, may not work out if either of them were grossly wrong. 

Reasonable corrections can be made after cutting the material from either the side frame pockets or bolster.  If a bit too much material was inadvertently removed, then the cut surfaces can be built up with small pieces of thin tape - acting like shims.  Conversely, if the material on either the side frame pockets or bolster is too much, a file can be used to take off the extra amount needed.

The truck assembly process is illustrated in the following pictures:

Checking and adjusting wheel gauge for back to back spacing.  An Aristo gauge can be used to check the back to back wheel spacing, and an automotive battery terminal  puller can be used to pull the wheel out if too narrow in gauge - typical of Aristo ART-29111B metal wheel sets.



Spacer washers of 0.032 inch thickness are needed to be placed on the axle tips to minimize axle side play (axle skew, angle of attack) that can cause drag when a car is operated on curve track. 


The truck side frames can be lubricated before the axles are installed.  A squirt of Labell 134 Teflon powder in each journal box can be used.

In the above picture, note the blue tape on the side frame pocket. This is an example where I removed a bit too much material, so I "shimmed it up" with a piece of blue painter's tape.

The truck is then reassembled


In the above picture, note the black tape on the butt end surface of the truck bolster. This is an example where I removed a bit too much material, so I "shimmed it up" with a piece of duct tape.

NOTE: When mounting the truck on the car the pivot post will protrude some.  A 1/4 inch hole size by 0.047 inch thick washer (Digikey #3182K-ND) should be placed over the protruding part of the post and under the screw mounting head so as to minimize excess vertical movement.

Floor Modifications

The floor must have some simple to do  modifications to it so that the modified truck when installed will freely pivot.
The bolsters must be notched near the screws and the little rib next to the pivot post where the truck mounts must be removed.  These modifications allow the mounted lowered truck assembly to freely pivot.


The reason for removing the rib adjacent to the truck pivot post is provide for a leveled attitude of the truck when it is installed.  Without doing this, the car actually would not be lowered as best possible (by a very small amount), and the car may have trouble articulating when crowning over less than ideal track work.


A file can be used to horizontally notch the bolsters. The notches are to be placed (counting bolster rivets) at the 7 to 9th rivet from sides of the car.  The bolster screws are to be removed during the filing process. (When the bolster screws are replaced, the heads may be higher than the notched area; however, when the truck is installed, it will not interfere with it.)







Depending on tolerances or other reasons - intended or not, it may be necessary to notch the two inboard floor ribs for each truck to provide some wheel flange clearance as shown below.

The halfmoon (actually a crescent) clearance is advisable on the floor ribs just under the inboard wheels.

Mounting Kadee 907 Centerset Coupler Assemblies

Note the traditional Kadee 789 centerset coupler assemblies will mount the same way.
Mounting is done such that no screws will show on the top decking surface of the flat car.

Kadee 907 coupler assemblies were chosen for their small footprint.  Though I believe Kadee 906 / 830 (also centersets) may perform better, the smaller footprint of the 907 / 789 is  more visually appealing  and prototypical looking on a car with such little end bulkhead area that would be overwhelmed with the larger 906.

Shown in the below picture is a mounted Kadee 907 coupler assembly.  As can be seen, the car's end bulkheads must be removed first.  The bulkheads are to notched out before they can be reinstalled - discussed later.

As can be seen in the above picture, a metal bracket is used to mount the coupler box assembly.

Bracket detail is shown below.

The bracket is configured in such a way that screws will not be noticeable on the top surface of the car . The below picture shows the top of the flat head screw that retains the front of the Kadee coupler box assembly in conjunction with the bracket.  When the end bulkhead is fully installed, this screw head will not show.


The dimensional drawing used for fabricating the bracket is shown below.



The bracket installation process is illustrated in the following pictures:

The bare bracket can be used as a template to locate its rear mounting hole in the floor's coupler pad rib as shown below.  A scribe is used as a punch to locate the hole center in the soft plastic rib.


Once the hole location is established, it can be drilled and tapped for the 2-56 screw.




The "stud" (a flat head no. 2-56 x 7/16 inch long screw) is to be fastened to the bracket with a lock washer and nut, then the bracket is screwed to the floor pad rib as shown below.

It may seem a bit awkward to tighten down on the bracket's rear screw with the stud in the way, but the screw merely needs to be lightly snugged - besides which the installed coupler box rear tail will keep it in place.  Alternatively, a tight clearance hole can be used in place of the threaded hole in the plastic rib so the screw could be pushed in since its purpose is the keep rear of the bracket tight against the floor pad rather than tight against the rib as the front screw is sufficient to keep the bracket from  horizontally pulling away.  That said, I believe it preferable that the rear screw be threaded into the plastic floor  rib, and if not threaded, that it be  retained by a nut.


It's OK (even desirable) if the bracket somewhat sticks up in the front once the rear screw is in place.  This ensures the rear corner of the bracket will be firmly seated on the floor pad when bracket is forced  flat as the front screw is fastened through the floor, bracket and coupler box assembly.


Mounting the Kadee Coupler Box

The three pictures that follow are for the purpose of illustrating the coupler box relationship with its mounting bracket and NOT meant to imply that they should be pre assembled.


If the clearance hole method  in the floor rib was chosen, the coupler box assembly could be pre attached to the bracket; otherwise, do NOT pre attached the box assembly to the bracket.



Note how the Kadee coupler box tail's "half moon" envelopes the pan head screw at the rear of the bracket when installed.  This helps to center the Kadee box and confine the screw at the same time.



The existing  hole located near the ends of the floor's upper surface must be counter sunk.


Mount the Kadee coupler box over the bracket stud with lock washer and nut, but LOOSLY fasten it at this time.

Install a no. 2-56 x 3/4 inch long flat head screw through the hole at the end floor surface - passing through the front hole of the Kadee coupler box assembly,  then place lock washer and nut on the screw.



Tighten both nuts so the Kadee couple box assembly is firmly in place.  (Shims may be required under the box after checking with the Kadee 980 / 880 gauge when the car is placed on the track.)

The Kadee 907 kit includes a capsule containing several small 0.010 inch thick shims.
On  the cars modified for lowering I've completed thus far, I found that placing a stack of 3 shims under the front of the coupler box and one shim at the rear allowed the coupler to align with the Kadee 980 gauge.



With the trucks mounted on the car and the car placed on the track, check with Kadee 980 / 880 gauge for coupler to railhead height.


IMPORTANT:  Shim under the box as required for proper coupler alignment with the Kadee gauge before putting the end bulkheads on. 

Notching the End bulkheads

Before the end bulkheads are installed on the car they are to notched in order to fit over the Kadee coupler box assembly.

Shown below is a dimensional drawing that can be helpful for locating the notch.


A razor saw and Dremel tool can be used to cut out the notch as illustrated in the following pictures:

Making a cardboard template may be helpful in locating the notch on the bulkheads if doing many cars.

The completed notch is shown below.

 

The end bulkheads should only be installed after the proper coupler height is established since shimming can't be done with bulkheads in place because the end screw would be covered up with the bulkhead.

Shown below is the car "buttoned up" with end bulkheads installed and coupler height re verified with the Kadee 980 gauge.


Having checked in various railroad books, the slight projection of the installed Kadee 907 coupler box assembly "striker plate"  is prototypical.



After the coupler boxes and modified trucks are mounted, the flat car measures 1.60 inches from the railhead.  That's 0.200 inch lower than before the car was modified

Adding Weight to the Flat car

The Aristo 40 foot flat car as it comes from the factory, and then fitted  with Aristo ART-29111B metal wheels, weighs only about 1.7 pounds.
 


Thus, depending on the layout the flat car is operated on, it is at high risk of "string-lining" around curves when placed in a long train.  To prevent this, most folks are probably happy to place a load on the car and be done with it.  On the other hand, if you like to emulate prototypical operations with out any load, the flat car can be weighted without noticing it from the outside.

There are two separate methods that can be selected from or collectively combined to increase the weight of the car.  The fist method is to add weight along the underside spine of the car, including the bolsters.  The second method is to add weighted box tubes (one each) nestled against the drop down (fish belly) underside of the car.



Method 1, Adding Weight Within the Spine & Bolsters of Car Floor

The first thing to do is to remove the underside brake rigging apparatus



A 25 pound bag of lead shot used for weight can be purchased at a Gun Store.  The no. 9 lead shot size is fairly small in diameter and will easily fit through a drilled hole.



Since most Aristo production run floors have the upper and lower parts glued in place, a 3/16 or 7/32 inch size hole will have to be drilled into the base of the bolster to gain access so lead shot can be inserted. 



When pouring in the no. 9 lead shot, be sure to shake and tap the floor assembly so that the bolster cavity is completely filled as best as can be done.



After inserting the lead shot, the hole can be sealed by CA gluing a small rectangular plastic cap over the opening.  The cap can be cut from a 3/32 thick ABS plastic strip that is 0.315 inch wide. The cut length (height) should be 0.360 inch.  The plastic can be purchased from TAP Plastics, Inc. 
The picture below shows an excess amount that must be cut.



After installing and CA gluing all the litte0.315 inch wide x  0.360 inch deep bulkheads in the spine of the car  needed to retaining the lead shot (5 places - 10 bulkheads), the lead shot can be poured into the each location and leveled off so a length of precut 0.315 inch wide material for lids can be fastened. 



Before pouring the lead and after leveling it, put some glue in.  I used a non damp, non foaming  urethane glue.  This keeps the lead shot in place as well as assuring the lids are  bonded.

Note that some Aristo Flat Cars have the sides glued in place on the floor, and with some cars the glue does not hold too well.  On these cars, you may as well remove the sides from the floor. They can be easily glued on later using CA glue.  That said, you don't need to take the sides off.  For the second UP car I modified, the sides were left in place as they appeared well fastened at all points.



You can progressively go from one end of the car to other whilst clamping all locations - leaving the clamps in place until the glue cures.



Method 2, Adding Auxiliary Weights

An pair of weights made from 6 inch lengths of square steel tubing filled with no. 9 lead shot can increase the weight of the car by 0.70 pounds.  This can be used to augment the weight added to the spine and end bolsters of the car, or in place of it. 



After adding the no. 9 lead shot to the spine and bolsters of the car, the weight becomes 1.7 pounds + 0.5 pounds for a total of 2.2 pounds - shown below.


If the pair of lead filled square tubing is used as an alternative to adding weight to the spine, the car will become 1.7 pounds + 0.7 pounds for a total of 2.4 pounds rather than 2.2 pounds. Some folks may find this to be the easier method of the two to do.

But If using the auxiliary weights to augment the weights added to the spine and bolsters, the total becomes 1.7 pounds + 0.5 pounds + 0.7 pounds for a total of 2.9 pounds. The following two pictures show two example cars, the SP one is below . 

The UP car is the second car I had modified.  It appears to be fairly consistent as seen below.


Thus, there is flexibility for adding weight depending on one's layout needs whether none, one or both methods are employed.

Shown below is dimensional drawing of the steel tubing weights and  retaining clips that can be helpful for making them.



Shown below it the small forked bracket for retaining the weight against the underside belly of the car.
The curvature of the belly makes for a natural niche such that only one  retaining clip is needed, being fastened with the existing floor screws.


Shown below is how the no. 9 lead shot can be added to the tubing weights and then plugged.
Like when adding weight to the floor bolsters, a large coffee can be used to hold all 25 pounds of no. 9 lead shot.  Then with the tube partly immersed, a small detergent measuring cup is used to pour the little balls into the tubes.  Of course one end of the tube must be plugged first.   I also, put some glue in the ends before pressing them in.



As luck would have it, the plugs used are salvaged from the USAT truck coupler tangs, cut like a square with ends beveled so they can be press fit in the tube ends with a small plastic mallet.



Once the tubes are filled with no. 9 lead shot, they are to be plugged.


Any excess plug ribs sticking past the tubing ends could be removed / filed off.

Using Solid Steel Stock as Weights

Half inch square solid steel stock  can be used as an alternative to the lead filled hollow steel tubing.  Since the lead shot, small as it is, can't be packed into the hollow tubing like it would if melted and poured in, the solid steel will actually weigh marginally more.

I purchased half inch square solid steel stock from Orchard Supply Hardware that they had in one foot lengths.  Cutting it in half is best done with a power saw; otherwise, it might be a very laborious task.



I installed the solid steel stock as weights in the Aristo Western Pacific flat car after doing the other modifications to it.
Since this particular car had bulkier washers under the screws where the weights would rest on, added clearance was needed so a small dimple was ground at the center edge of each weight.  The solid steel stock has square corner edges compared to the hollow steel tubing - so this, too, contributed to the need for grinding the dimple.

Aristo Flat Car Variations

The remaining type of Aristo flat car to be modified includes the bulkhead end flat car - with and without factory installed load. 
The example bulkhead type car without the factory load is a Pennsylvania car.
Here the car is shown having been lowered and fitted with Kadee 907 centerset couplers.


Before the car was modified, but having Aristo ART-29111B metal wheels, it had a measured weight of 1.9 pounds.


After the car was fully weighted (lead filled floor spine and auxiliary metal tubing), it measured 3 pounds.


The example bulkhead type car with the factory pipe load is a Southern Pacific car.
Here the car is shown having been lowered and fitted with Kadee 907 centerset couplers.


This car did not need to be weighted since it measured 2.76 pounds with the factory pipe load - virtually the same as an Aristo box car with metal wheels.

Operational Results

The lowered SP flat car was tested for Kadee coupler operation in my loft - just using a GP40 and box car coupled to it.





The modified, lowered flat car uncoupled and re coupled as expected with no problems.



The modified, fully weighted (2.9 lbs), lowered Aristo 40 foot flat car performed without incident when operated on severest part of the 270 degree loop back of my under house layout.  With the car being the first behind the locos in a 62 car train, the couplers stayed coupled.  There was some evidence of slight wheel lifting when with the car in the train was nearing the exit of the 270 degree loop back - but no more so, actually slightly better,  than a standard Aristo box car (with metal wheels).



An overhead view is shown below on the 270 degree loop back.



Shown below are inside and outside views of the modified flat car coupled to the trailing loco on the  270 degree loop back.



Note the high stress loading of the 62 car train on the flat car's 907 coupler caused it to assume an upward attitude.  The loco has been retrofitted with Datum Precision made CNC machined metal coupler boxes that house the same coupler from the  907 kit but to a much finer tolerance so the coupler can't move up and down as much as the one in the car that is loosely housed in a Kadee plastic box.



Shown below is a slight wheel lifting when with the flat car in the train was nearing the exit of the 270 degree loop back - but very impressive with such a load on it.  The Kadee 907 coupler action is surprisingly good, too.

 

Videos

Operating the modified Aristo flat cars on the under house layout:

Appendix A - Aristo 40 ft. Gondola - Lowered With Kadee Centerset Couplers

Example Aristo-Craft 40 foot gondolas - both equipped with Aristo ART-29111B metal wheels: The otherwise as received Aristo Factory Rock Island gondola is shown on the left, and the lowered Union Pacific Gondola at the right having been modified (equipped with Kadee 907 centerset body mounted couplers & modified USA Trains brand Bettendorf trucks).

The Aristo Gondola is lowered using the same techniques as done with the flat car; however, it is a bit more involved as the drop-doors along with the "U" ends must be removed. This should be done one at a time so the sides of the car maintain some support whilst working on the car.

The end view shown below is of the modified Union Pacific car.

Like the flat car, the ends of the car ("U" shaped ends for the gondola) are held in place with several small screws - resembling those used to hold eyeglasses together, albeit with a different thread pitch. Nonetheless, if screws are lost or missing as happened on one car, some of the screws in repair kits for eyeglasses can be substituted. The kits may be found in drug stores.

Gondola Disassembly

First, remove the original Aristo truck assemblies from the car.

The brake wheels are to be removed so as to gain access to an adjacent tiny screw fastener. Though it may seem a screw driver could be inserted through a brake wheel slot, this will not work too well since the screw driver is restricted at an angle just enough that it won't properly engage the screw head - risking stripping it out.

Shown below are self explanatory pictures illustrating the process of removing the brake wheels, "U" ends and drop-doors from the car.

The hole that the brake wheel fits into may be very tight restricting movement of the wheel due to paint buildup when the car was made. If the force needed to twist the wheel seems like it will bust it like it did on the SP gondola shown below, a pin vise with small drill can be used to drill a small hole from the back side in order to free it up.

Gondola Car Body Modifications

With the drop door removed and out of the way, countersink the upper side of the floor's end hole to accommodate a 2-56 flat head screw. Not much material needs to be removed, and the plastic is very soft - so this is preferrable to do by hand using a large drill bit requiring only a couple or so light twists.

After the coupler mounting bracket is fabricated the same way as described for the flat car it can be used as a template to locate its rear mounting hole in the floor's coupler pad rib or you can use measurements to locate the hole (centered and 0.20 inch up from the pad).

The no. 2-56 "stud" screw is to be installed in the countersink hole of the bracket - then the bracket as an assembly can be fastened to the floor.

The floor bolsters are to be notched using a file in the same way as described for the flat car where the notches are placed (counting bolster rivets) at the 7 to 9th rivet from sides of the car. The bolster screws are to be removed during the filing process. When the bolster screws are replaced, the heads may be higher than the notched area; however, when the truck is installed, it will not interfere with it.

The Kadee 907 or 789 coupler assembly can be mounted before or after the floor bolsters are notched - or wait until after the "U" ends are modified and installed; however, shimming - if needed - will be done after trucks are installed and the car is placed on a track with Kadee 980 / 880 coupler height gauge.

The "U" ends of the car are to be notched to accommodate body mounting Kadee 907 or 789 centerset coupler assemblies as shown. This is in concert with using the lowered USAT Bettendorf Trucks as described for the flat car.

Re-assembly of car body

Be sure to reinstall the drop-door before the "U" end is installed. The car's drop doors and "U" ends are installed in the reverse order of how they were removed. If the tiny screws that hold the "U" ends seem loose, a small dab of glue in their recesses can be used to help keep them in place fairly well since the forces on the screws will normally be in the car's longitudinal plane so they are unlikely to be pulled out.

The brake wheels can be reinstalled now - or preferably later if (and after) weights are added to the under frame of the car.

Coupler Assembly Installation

The Kadee 907 / 789 coupler box assembly installation is described and illustrated in the following pictures - commencing with the bracket:

Truck Installation

The USAT trucks modified as described for the flat car are installed on the Gondola.

Because the car bolster pivot post protrudes past the thickness of the USAT truck bolster, a nylon washer with a quarter inch hole is installed over the post under the fastening screwing. The outer edges of the washer may need to be trimmed off. The washer keeps the truck to car body from having excessive vertical slack which otherwise may cause undesirable car wobble.

Like the flat car, the floor ribs need to be ground as shown below so the truck wheel flanges don't interfere when the truck pivots.

The installed, shimmed coupler box assemblies align with the Kadee 980 track gauge as shown below.

Adding Weights

Like the flat car, adding weight to the Gondola can be done the same way. Shown below are clipped on added half inch square steel stock about 6 inches long to each side of the floor underside.

For comparison, the Aristo Wabash Gondola, factory unmodified but having ART-29111B metal wheels measured 2 lbs. (My digital scale stopped working so I had to resort to the old analog scale.)

The completed, lowered Southern Pacific Gondola having modified USAT trucks and metal wheels with Kadee 907 body mount centerset couplers measured 2 lbs, 12 oz (2.75 lbs).

If a covered top is included, the total car weight measured about 3 lbs, 2 oz (about 3.1 lbs).

Measured Result of Lowered Aristo Gondola

The Aristo Gondola lowered using modified USAT trucks measured about 0.22 to 0.23 inch lower than the Aristo unmodified factory car with original Aristo trucks. (Both cars have ART-29111B metal wheels.)

The Wabash car on the left is unmodified and the Southern Pacific car on the right is the modified, lowered car using modified USAT trucks and having body mounted Kadee 907 centerset couplers.

Custom Lengthened 52 ft. Gondola - using simpler coupler mount bracket

I acquired a lengthened Aristo D&RGW gondola from Paul Burch which was so well done by him it's difficult to see how it was accomplished!
The lengthened gondola measures about 21 &3/4 inch across the draft gear strikers, which for this 1/29 scale car, scales up to 52 feet and 7 inches. This car was not lowered but fitted with Aristo Barber emulated roller bearing trucks. Due to its longer length, it does not appear to be tall off the railhead.
However, the gondola had #1 scale centerset couplers, so I changed them to "G" scale centerset couplers to be compatible to my rolling stock. In so doing, a simple metal bracket was made to retain the G scale coupler housing without having to drill holes in the car's deck. This bracket is a simpler alternative to the previously describe bracket - illustrated below

End , -Ted