Custom Made Coupler Boxes & Kadee Centerset Couplers for Selected Aristo-Craft Locos

(Includes GP40, SD45, Dash-9, RS-3, RDC, and E8 / E9)

By Ted Doskaris

January 2, 2011 Rev GE-A
January 19, 2011 Rev GE-B  Added material, including Appendix A for GE Dash-9 application

February 19, 2011Rev GE-C  Added material; Appendix B for ALCO RS-3 application

February 21, 2011 Rev GE-D  Added material

February 28, 2011 Rev GE-E Added Appendix C for Budd RDC application

March 9, 2011 Rev GE-F  Added RS-3 material

March 10, 2011 Rev GE-F1  Clarifications

July 3, 2011 Rev GE-G  Added Appendix D for E8 / E9 application

July 5, 2016 Rev GE-G1 - removed links to video hosted by ill-fated flipshare, and added embedded youtube video link

October 6, 2018 Rev GE-G2  Fixed stale links

December 16, 2018 Rev GE-G3 Added local links for GP40 & SD45 installation

May 13, 2019  Rev GE-G4 Fixed stale links, including embedded video link; Restored non appearing image

December 3, 2019  Rev GE-H Added Info. for obtaining Datum Precision Boxes

February 11, 2024 Rev GE-J Added optional "CamPac" Laser Cut E8/9 metal support plates

Coupler Box Features
 

• Applicable to Aristo's GP40, SD45, Dash-9, RS-3, and E8 / E9 locos for mounting Kadee centerset couplers with potential for other applications
• Meant for operational use on locos pulling long, heavy trains with commensurate drag
• Non flexing, strong metal box made with 6061 type aluminum, CNC machined - including 2-56 screw thread for lid mounting
• Black anodize finish
• Tighter tolerance restricts up and down coupler wobble to a bare minimum
• Accepts Kadee couplers that include the new "G" scale AAR E type model 901 centerset coupler
• Accepts Kadee plastic lid and centering springs

Note: Loco operation is intended for 8 foot diameter or greater curves. Layouts with "S" bends are to have a straight section the length of the longest loco / car, or greater, between opposite diverging paths.

Preface

I have been converting "G" scale locos and rolling stock to Kadee centerset type couplers having completed over 400 items as of this writing.
In this regard, the Kadee Quality Products Company provides a variety of offerings for the modeler to do the conversions fairly easy. Of particular significance, couplers are offered in centerset, medium offset and large offset type configurations housed in many different types of coupler boxes with Kadee recommending the 787/ 908 having medium offset couplers for use in the Aristo-Craft GP40, SD45, and RS-3 locos and the centerset 789 / 907 couplers for the Dash-9 locos and RDC.
Whilst vertically offset couplers make conversions friendly to do, they do have the trade-off of diminished operational performance when loaded (tend to lever downward) and, of course, their poor aesthetics (side view not prototypical).

For more information about this, see:

Vignette, "Kadee Coupler Body Mounting Considerations" (Car Height & Attitude, Floors, Trucks, Wheels & Prototypes)

AND:

"BAGRS 2/’18 Clinic presentation, "Body Mounting Kadees with focus on 1/29 Scale"

The Metal Coupler Boxes - GP40 & SD45
For a description about the metal coupler boxes and information pertaining to the GP40 & SD45, first see:
The GP40 & SD45 application
For the GP40 & SD45 installation, see:
The Aristo GP40 & SD45 Installation

The Dash-9

When using the Kadee 789 or 907 centerset coupler assemblies on the Dash-9, I found them to have a low horizontal alignment when checking with a Kadee track height gauge. Also, the plastic coupler box hole location used for the mounting on the loco's pedestal results in having the box project out more than it needs or should be.
See Appendix A for the Aristo Dash-9 Datum Precision coupler box application.

The RS-3

The installation of the coupler boxes on the RS-3 require more time and effort compared to that of the drop-in application of Aristo's GP40, SD45, and Dash-9 locos using the same boxes.  In this regard, the RS-3 coupler mounting pedestal must have its vertical side ribs trimmed lower, and in most cases, the pilot must be somewhat notched out for the coupler box. Washers and shims may then be required to level the installed coupler box assembly for proper coupler alignment with a Kadee coupler to track height gauge.  Thus, this application requires a degree of "trial and error" for achieving a best end result - owing, in part, to factory build tolerances of the loco.
See Appendix B for the Aristo RS-3 Datum Precision coupler box application.

The RDC

The RDC is a less likely candidate for Datum Precision coupler boxes since the RDC would typically be operated by itself, or maybe with another RDC or two. Thus, the need for proper coupler alignment conforming to train cars or locos other than itself would not seem to be critical, nor would coupler box strength be as important like that of locos pulling heavy trains.  That said, the Datum Precision coupler boxes equipped with Kadee centerset couplers can be installed on the RDC, if only for aesthetic reasons having alignment consistency with the Kadee coupler height gauge.
The installation of the coupler boxes on the RDC is sort of a drop in, but it does require more time and effort compared than that of the application on Aristo's GP40, SD45, and Dash-9 locos using the same boxes.  Whilst the RDC coupler mounting pedestals are not altered, the mounting of the coupler box itself necessitates washers / shims that can vary in thickness by a noticeable amount from one end of the car to other - let alone from car to car - so as to align the installed coupler box assembly for proper coupler alignment with a Kadee track height gauge. Thus, this application requires a degree of "trial and error" for achieving a best end result owing to factory build tolerances of the RDC.
See Appendix C for the Aristo RDC Datum Precision coupler box application.

The E8 & E9

The Aristo EMD E8 / E9 (outward appearance virtually the same) at first seemed to be more of a challenge with two versions to contend with. One version is the so called "freight pilot", and the other version is the so called "passenger pilot". The pilots are held in place by a couple of screws; thus, the factory can configure a given version very easily by this part swap - along with the appropriate road name livery.  The passenger pilot protrudes outward more the freight pilot, so the coupler box mounting has to address this. It turns out that a user has choices that accommodates both operational and aesthetics considerations.
The implementation is relatively easy to do, and the results are very pleasing - being almost prototypical in appearance.
See Appendix D for the Aristo EMD E8 / E9 Passenger Loco Application

Obtaining Datum Precision Metal Coupler Boxes
Click on above for that info.

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The GP40 & SD45 Application

As a solution, I modified the plastic Kadee 831 type boxes (used in the 789 / 907 centerset coupler assemblies) for use on the Aristo GP40 and SD45 locos.
Modifications to the plastic boxes included making thin slice cuts in order to mount the boxes in the locos so that the centerset couplers can be used.
I wrote about this in the article, Aristo GP40 & SD45 loco retrofit with Kadee 789 centerset couplers .


Best Solution - Custom Made Metal Coupler Box

Though I had successfully completed many GP40 and SD45 conversions using the modified plastic boxes, I still had many more to do - so I discussed the prospect of custom made coupler boxes with owner, John Jans, of Datum Precision Incorporated.

This is the same company that I had custom make stainless steel wheels for use on Aristo's SD45, GP40, Dash -9s, and E8s. (See article, Stainless Steel Wheels For Aristo's "Prime Mover" Diesels - A viable alternative )

Proposed coupler box 3-D animations are shown below.


I provided an example modified plastic coupler box assembly and a preliminary drawing to John from which evolved a Solid Works model in order to produce a quantity of CNC machined 6061 aluminum metal, black anodized, coupler boxes. The new box is not an identical copy of the plastic box I had modified.

The new coupler boxes were made by Tim at Datum Precision using a MAZAK CNC machine in groups of 5, resembling crackers or wafers.


John explained that the metal boxes can be made of tighter tolerances than compared to what is allowed for molded plastic boxes; thus, the characteristic vertical wobble of installed couplers was virtually eliminated.

Quantity of received coupler boxes shown below.
(I had sufficient quantities made to satisfy my needs and to accommodate the piece part price trade-off for a minimum quantity order. Shipping, etc. not included.)

Coupler boxes are shown as received in honeycomb trays.


The new coupler boxes are intended to be used with the Kadee couplers, springs and plastic lid. Accordingly, the box was CNC machined with a drilled and tapped hole for a 2-56 flat head screw to secure the plastic lid.

Shown below are various views of the new aluminum, black anodized coupler box.



These new metal boxes are very strong and accept both the older style centerset couplers that come in the Kadee 789 kit and newer type AAR "E" type 901 centerset couplers that come in the Kadee 907 kit.  The boxes were made to be adaptable to other potential applications, so a longer than needed tail shank was decided upon that can be cut short for the GP40 application.

Shown below is comparison of coupler box assemblies


The shank repositioning on the new metal box with respect to the coupler pocket is very strong - something that can't be equaled with plastic - likewise for the pocket's reduced floor thickness.


Shown below are views of an assembled box with Kadee parts.

It's important that the screw that retains the coupler box lid not be so long as to protrude past the opposite surface so that an installed box will seat flat on the loco's pilot lip.
Accordingly, a readily available 2-56 x 5/16 inch long flat head screw is used to secure the lid in place of the Kadee screw.  

Kadee's newer 901 AAR "E" centerset couplers are installed in the examples here.  Note: The Kadee 901 (couplers only) are meant as replacements of couplers in the older Kadee 789 kit. The newer Kadee 907 kit includes the AAR "E" type 901 couplers.

The Aristo GP40 & SD45 Installation

The original Aristo knuckle coupler assembly can be removed from the loco without cutting it off (as purported by some folks) by dismantling and extracting it piece by piece in situ. For details on removal and installation techniques -albeit for plastic modified boxes, see article, Aristo GP40 & SD45 loco retrofit with Kadee 789 centerset couplers .

Example locos used for illustrating the new coupler box installation include a Wisconsin Central SD45, a Rock Island GP40 and a Union Pacific GP40.








Shown below is example Wisconsin Central SD45 rear pilot opening with removed coupler assembly from its mounting pedestal.  

The reinforcing ribs can be seen on the sides of mounting pedestal below the round pivot area.

Shown below is the loco turned upside down. Note the pilot's inner sill span with the "T" leg projection meant for retaining the original Aristo coupler's centering wire like spring.


The Aristo GP40 and SD45 pilots are virtually the same; however, the coupler mounting pedestals' vertical height differ slightly in relation to the locos pilot opening with the GP40 having a somewhat taller post.
Because the new coupler box is made with a long shank for other potential applications it can be installed on the SD45 with a little flexing of the pilot's inner sill, but the box cannot be installed on the GP40 without first trimming off the unnecessary portion off the shank's extremity. (Alternatively, the coupler box shank can be left as is by trimming off the loco pilot's inner sill interfering "T" leg projection meant for retaining the Aristo coupler centering spring.)  I chose to remove the unnecessary extremity of the new coupler box shank - amounting to separation of about 0.33 to 0.35 inch from the coupler pocket wall as shown below.


Before placing the new coupler box shank on the SD45 mounting pedestal, a spacer washer trimmed like a "D" is required to be first installed on the post. A nylon (1/4 inch hole) washer of 0.047 inch thick can be used. These washers can be purchased in quantity via mail order from Digikey - part no. 3182K-ND.

The picture below shows why the washer is to be trimmed like a "D" with it on the underside of the new coupler box assembly. Note, too, the notch machined in the box is to allow the box to envelop the pedestal's front rib.


Shown below is example Wisconsin Central SD45 coupler box mounting (upside down view) with shank placed over washer on mounting post ribs. During installation, it may take some maneuvering of the washer with a thin pointed tool (scratch all) to properly line up its "D" side so everything correctly slides down on the post.


Before installing the new box on the GP40, the 15/64, 0.234 inch, hole sized for the SD45 in its shank must be somewhat enlarged to 0.242 inch (Letter C drill size) (Though a letter "C" size drill is not typically available in stores, it can be purchased from Granger, item #2G440)

The increased hole size is required due to the increased angle that the box must tilted at when installing it through the pilot opening and because the diameter of the pivot on the GP40 pedestal is somewhat larger than that of the SD45.

See installation picture illustrations to follow:

Shown below is example Union Pacific GP40 coupler box mounting (upside down view) with shank placed directly on mounting post ribs - no spacer washer used.

Likewise, below is an example Cotton Belt GP40 (right side up view).


For both GP40 and SD45, fasting down the new coupler box requires using a washer to take up the area of the exposed pedestal pivot. I used a nylon step washer (1/4 inch hole) purchased in quantity via mail order from Digikey - part no. 7687K-ND. The overall thickness of this washer, including the step, is about 0.062 inch. The picture below shows why the washer is to be trimmed like a "D" nearest the step portion with it placed on the lid side shank of the new coupler box assembly.


Shown below is new coupler box assembly screwed down with the step washer having been placed over the exposed area of the pivot post.

The depicted examples GP40 above and SD45 below are the same. (Note the pilot inner sill downward "T" leg projection that originally housed the Aristo knuckle coupler centering spring. This "T" leg could be removed to facilitate the new coupler box installation so that its shank extremity would not have to be removed - particularly for the GP40 installation.)


Shown below is a side view of the installed coupler box assembly with the step washer on the top (loco turned upside down). The "D" trimmed step washer is used for both SD45 and GP40 locos. The whole coupler box assembly, including nylon washer/s, is held down and fasten to the mounting pedestal using Aristo's original screw and metal washer. It is important that the metal washer is positioned to bear against the entire ridge surround of the step washer. This ensures that the coupler box is squared-up and rests against the loco's pilot lip.

A closer view is shown below. Note the coupler box underside "D" trimmed washer at the pedestal base is only for use on the SD45 as depicted in these examples.


Shown below is the intended fitment of the new coupler box assembly with its front resting on the loco's pilot lip.

Using the step washer facilitates the desired effect of a two surface point mounting of the coupler box when the retaining screw is tightened down on the washer's step ridge; thus, the coupler box becomes "squared-up" with the pilot opening.

In some cases, thin shims are used on selected areas of the pilot or under the coupler box to further align the coupler box assembly so that the proper rail head to coupler alignment conforms with the Kadee coupler height gauge. (Kadee 880 / 980).
Kadee provides 0.010 inch thick shims in some of its coupler assembly kits. These or similar substitutes can be notched to best slip under screw areas as shown below.

Though many locos did not require doing this, shown below is an example Rock Island GP40 that benefited greatly for ones like this that trend to have pitched in pilots. Inserting the small shims under the pilot fastening points has a profound effect on leveling the pilots front lip for aligning the coupler.

Shown below is how the thin shims served to square-up the front pilot. Though the example here is of a GP40, the same technique is used for both GP40 and SD45 locos.

A Rock Island GP40 example is depicted above whilst a Union Pacific GP40 is depicted below.

Shown below is the proper coupler alignment of the example Rock Island GP40 using the Kadee 980 coupler height gauge.

Shown below is an overhead view.


Shown below is the proper coupler alignment of the example Wisconsin Central SD45 using the Kadee 980 coupler height gauge.






For both GP40 and SD45, the operational use of these locos with the new coupler boxes is intended to be on a track diameter of 8 foot or greater.
The coupler box as mounted on SD45 has the closer proximity to the trucks.
Shown below is the example Wisconsin Central SD45 on 8 foot diameter track sections.

Shown below is the underside view of the SD45 on the 8 foot diameter track. Note there is sufficient clearance of the new coupler box shank - even with its extremity not being trimmed short.



Operational Results

First, a little about the layout

My layout is both indoors and outdoors. The indoors portion consists of a suspended roadbed system under my house - which is a walk space changing to crawl space as the house is located on somewhat of a slope on a hill. There is about 180 feet of mainline track consisting of somewhat circuitous "S" bends and curves (of mostly 10 foot diameter) to get around the various plumbing and furnace system. The longest straight portion is about 8 feet. The layout, somewhat shaped like a U, can be considered as a modified "dog bone" that consists of a self contained loop at each end. See article, Under house suspended layout article .

The test train & results

A test train comprised of 61 cars equipped with Kadee couplers was used to see how the new Datum Precision made coupler boxes performed. With the 61 car train at rest and couplers in tension the digital fish scale measured about 5.5 lbs to bring the train to an incipient rolling condition, after which maintaining movement dropped to about 5 lbs.

Example locos used for illustrating the new coupler box operation include 1 ATSF yellow bonnet SD45, 2  ATSF Kodachrome SD45s, 1 Southern High Hood SD45 and 2 Cotton Belt GP40s. All of the these locos have the Datum Precision made coupler box assemblies installed having the Kadee 901 center set couplers. (They also happen to have the Datum Precision made stainless steel wheels installed, too.)

The train was pulled with the 3 ATSF SD45 locos for a first test - shown below .


The following pictures taken on the layout's 270 degree 10 foot diameter loop back illustrate the trailing SD45 loco coupled to the first car of the 61 car train. The loop back is the most stressed area for checking train operation.
Overhead view shown below

Inside SD45 view shown below

Outside SD45 view shown below

Outside SD45 view close up shown below


Shown below is an outside view of the two Kodachrome SD45s coupled to one another on the 270 degree loop back.


Shown below is the trailing SD45 loco with the same 61 car train at a different location on the layout on an "S" bend track area.



Then for a second test, the train was pulled with a GP40 / SD45 / GP40 lash up - shown below.


The following pictures taken on the layout's 270 degree 10 foot diameter loop back illustrate the trailing GP40 loco coupled to the first car of the 61 car train:
Overhead view shown below

Inside GP40 view shown below

Outside GP40 view shown below

Outside GP40 view close up shown below


The train and both GP40 and SD45 type of locos having the Datum Precision made coupler boxes with Kadee 901s performed flawlessly whilst continuously operating on the layout.

Conclusions

Though it can be seen that an occasional slight amount of coupler vertical mismatch on some areas of the layout happens as anticipated under stress conditions, no coupler vertical slip outs, pull-aparts, or un couplings were prevalent during train operation - nor did the train string-line as it was stressed whilst going through the 270 degree loop back.

Obtaining Datum Precision Metal Coupler Boxes

The Datum Precision metal coupler boxes were designed by me (Ted Doskaris) in concert with Datum Precision, Inc. which makes the boxes.

The mechanism to procure these custom made coupler boxes requires a minimum quantity to be determined at the time of an order.

It is to be appreciated, too, that Datum Precision primarily makes high precision parts for various customers and may interleave coupler box orders with other work loads, hence, there can be a lead time of obtaining material and to schedule when boxes can be made. Datum Precision can neither be expected to enter into a dialog nor accept orders for the boxes from individuals.
That said, to accommodate those interested in obtaining the Datum Precision Metal Coupler Boxes, please Contact Colin Camarillo (who, also, provides our plastic 3-D printed CamPac BoxesTM for various applications). .

General Info. about coupler box assembly:

Appendix A - The Aristo GE Dash-9 Application:

Shown below are Aristo Dash-9s with Datum Precision made coupler boxes equipped with Kadee centerset couplers.


I equipped and tested a pair of Aristo Dash-9 locos with the same Datum Precision made coupler boxes using the same mounting hole location as used for the SD45 and GP40 application, and they worked excellently on my layout consisting of  mostly circuitous 10 foot diameter curves and some eased in & out "S" bends.  And this is with the coupler projection being minimal and almost prototypical with the new boxes mounted in the Dash-9s.

I, also, operationally tested what I believe to be the worst case configuration on my layout - that being two Dash-9s coupled nose to nose pulling a 61 car test train (The lash up also included two GP40 lead units, of course, equipped with the same Datum Precision coupler boxes.

I tried and installed both older type Kadee couplers from the 789 assembly and the new Kadee 901 AAR "E" couplers. A Union Pacific Dash-9 test loco got the older style couplers with a Southern Pacific Dash-9 test loco getting the newer style couplers.

I, also did a static test on the two Dash-9s coupled nose to nose on an 8 foot diameter track. With the couplers in tension or a in a relaxed state, there is still some minimal clearance between the closest points (ditch lights).
Shown below are the locos coupled together on 8 foot diameter track.



Shown below is a close up view

With the locos physically pushed together, the ditch lights touch. So when I get to testing live operation on 8 foot diameter track, they just may very well work unless used as pushers on a train - again this may only be an issue if coupled nose to nose, as nose to tail or back to back configurations has a bit more room.

When using the newer Kadee 901s in the Datum Precision coupler boxes on the front pilot of the Dash-9, the under side ridge of the coupler needs to trimmed a bit so it does not interfere with the snow plow opening when swinging side to side.




Shown below are the two Dash-9 coupled nose to nose on a straight track.


The Datum Precision coupler box is actually easier to install on the Dash-9 compared to the SD45 and GP40 - though its tail shank, like the GP40, must be trimmed short - in this case no more than 0.400 inch from the coupler pocket wall.


Removing the original Aristo knuckle coupler assembly involves first taking off its centering spring. If it's not intended to restore the original coupler back on the loco, it's easiest to cut the spring off.  I chose to remove and save the spring, but to do so the motor block must be temporarily removed to gain access as shown below.

Then the original Aristo coupler assembly can be removed


Before installing the new coupler box, the MU cable (if not used) can be tucked in as shown below. This will prevent it from dropping into the track work with consequential chaos. This happed once on my layout as an MU cable got snagged into a turnout frog! (Like a Navy airplane landing on a carrier with arrestor hook.)
 

The new coupler box can then be easily inserted through the pilot opening and pressed down over the pedestal pivot as shown below.


The same nylon step washer as previously described for SD45 & GP40 is placed on the top of the installed coupler box assembly before fastening the original Aristo screw and metal washer. Note the inner sill area "T" leg nub where the original centering spring had been. This can get in the way during installation. If so, the sill can be flexed away as the box is pushed on the mounting pedestal.


Shimming:

Before adding shims, first check the coupler alignment with the Kadee 880 / 980 coupler height gauge to see if any are needed.
In many cases I usually had to do the pilot attachment point shimming to tweak for best coupler alignments - in this example using 0.015 inch thick washers.


I noticed when looking close at sides of Dash-9 front and rear porch areas near the pilots, there is a trend for them not being squared up. Some SD45s and GP40s were like this, too. Sometimes it is a subtle thing to see unless you check with a carpenter's square, but this can have a notable affect on coupler alignment.


In one rare case I needed to add a shim under the rear of the coupler box shank to further help tweak for best alignment. Using a duct tape cut to fit as shown below makes it easy.


One thing I noticed was that Dash-9 porches can be flexed up and down somewhat just using your thumb. (The SD45s and GP40s are not nearly as severe.) One reason is that the porch extensions do not have the chassis reinforcing ribs extending all the way beyond the pilot inner sill / bulkhead through to the end - as shown below.

With a Dash-9 pulling a heavy train, the porches with pilot ends (along with their coupler box mounting pedestals) can somewhat flex upward. In this regard, a SLIGHT downward coupler alignment tilt with respect to the Kadee track height gauge may be acceptable.

Shown below is the UP Dash-9 front pilot coupler alignment with the Kadee 880 gauge

Shown below is the SP Dash-9 front pilot coupler alignment with the Kadee 980 gauge


The picture below shows that the Kadee magnetic uncoupling feature works OK with two Dash-9s having been coupled nose to nose. I was able to operate the locos over the track magnet so that the couplers deflected properly and then uncoupled as they should.


Dynamic coupler actions can be observed the video below with two GP40s and two Dash-9s pulling the 61 car test train on my under house layout.

Appendix B - The Aristo ALCO RS-3 Application:



RS-3 examples described include five first generation production run locos (Southern Pacific, Union Pacific and D&RGW) characteristic of fully suspended trucks and little internal electronics, and one newer generation Rock Island RS-3 having ball bearing trucks, MU cables, and internal "DCC ready" circuit boards.  Externally, the generations of locos look the same (except for end railings) and are virtually the same height.  Both generations utilize the same techniques for installing the Datum Precision made coupler box assemblies.

To follow are self explanatory, annotated pictures for the Aristo RS-3 with Datum Precision made coupler boxes equipped with Kadee 901 centerset type couplers:

Overview:



Pilot subassembly removal:

The pilot subassemblies must be removed for modifications along with facilitating access to the coupler mounting posts for their modifications.  Each of the loco's end pilots can be removed as an entire subassembly. The newer generation RS-3 pilot has a captive MU cable through it, but it can be removed and set beside the loco with cable left in place.


 

Comments about needing to notch the RS-3 pilots:

I have completed fitting Datum Precision coupler box assemblies with Kadee 901 centerset couplers to six RS-3s that I have - the latest being the D&RGW early production run, non ball bearing motor block units.



I have found that most (but not all) RS-3s need to have their pilots notched to some extent to obtain proper coupler alignment with the Kadee coupler height gauge.  Of the six total RS-3s I have, 75% of the pilots needed to be notched (two D&RGW RS-3 pilots and one Rock Island RS-3 pilot did not.)



Of these three D&RGW units, two did not need to have of their pilots notched (one end only) in order to properly fit the Datum Precision coupler box assemblies. This is evidently due to factory build processes resulting in mounted pilots having an upward warp.

Shown below are two units with their short hood ends coupled together with the unit on the right having a notched pilot whilst the example unit on the left not notched.

Looking at the above picture clearly shows the unit on the left has a pronounced upwardly warped pilot compared to the unit on the right.
Shown below is the example short hood end unit having its upwardly warped pilot that did not need notching for proper coupler alignment with the Kadee 980 gauge.




Shown below is the same unit, but with its long hood end pilot having been notched for proper coupler box fitment and coupler alignment with the Kadee 980 gauge.


Shown below is the other D&RGW RS-3 (on the right) whose long hood end pilot did not need to be notched.


Shown below is the D&RGW unit coupled to the SP unit on the left - where the SP RS-3 pilot has been notched.

The comparative upward warp to the D&RGW unit's pilot can be seen on the right.

Notching the pilot:

Note: If an RS-3 pilot appears to have a pronounced upward warp, it is advisable to not notch it until first trying to mount the Datum Precision Coupler Box after having trimmed down the mounting pedestal ribs.

That said, the pilots more often than not must have their upper opening notched to accept the Datum Precision Coupler box.

Issues affecting installation and the newer generation RS-3:

Trimming the pedesal ribs:

The loco's coupler mounting pedestals must have their reinforcing ribs trimmed lower in order to properly position mounted Datum Precision coupler boxes.

Preparing the Datum Precision Coupler Box:

The Datum Precision coupler boxes must have unneeded tail shank material removed so that they can be installed with the pilots having been refitted to the loco.


 

Datum Precision Coupler Box Installation:

After the Datum Precision coupler boxes are placed on the loco's mounting pedestals, they are to be retained using a thin-wall sleeve to cover the exposed end of the pedestal, and then the original Aristo hardware is to be fastened.  A nylon flange bearing can be used for the sleeve.  Alternatively, the mounting post portion projecting above the installed coupler box shank can be cut-off flush with the shank; however, this is NOT recommended if for any reason you would want to restore the original Aristo knuckle coupler.



The RS-3 in a test train:

Example locos used for illustrating the coupler box operation include the one Rock Island RS-3 as the trailing unit along with four Rock Island GP40s. (Operation is desirably checked with the RS-3 as the trailing unit coupled to the first car of the train.)  All of the these locos have the Datum Precision made coupler box assemblies installed having the Kadee 901 center set couplers. (The 3 lead units also happen to have the Datum Precision made stainless steel wheels installed, too.)



The 61 car test train requires several locos to pull it through all the curves and "S" bends on the layout. That said, 5 total locos is more than needed.







The RS-3 and GP40s performed well together.





With the RS-3 coupled to the first car of the 61 car train, some vertical coupler off-set is normal for such a load on the 270 degree loop back.



The RS-3 and GP40s all equipped with Datum Precision Coupler box assemblies having Kadee 901 centerset couplers performed without incident pulling the load of a very heavy 61 car test train. There were no coupler pull-aparts or separations of any kind.

Appendix C - The Aristo BUDD RDC Application:



The RDC example to be described is of the Southern Pacific RDC1 characteristic of ball bearing trucks originally equipped with traction tires on the wheels of one axle for each truck.  I believe Aristo's newer generation RDC3 has done away with traction tires as they are unnecessary on a self propelled car weighing about 9 pounds - let alone not having the need to pull a train.
 


The RDC1 and RDC3 may externally look somewhat different; however, it is anticipated for them to be same with respect to installing the Datum Precision Coupler boxes.  In this regard, I only have the one RDC1 for evaluation.

RDC Preparation:

For RDCs having traction tires, it is desirable to replace them with wheels without traction tires, particularly if the tires are cracked and bulging above the wheel tread area as this may affect the car's coupler alignment.  Moreover, if using track power, having all wheels touching the rail head with metal tread surfaces assures power pickup so the car won't stall-out like the example SP RDC1 did on turnout / rerailer sections of my layout.





As shown below, to help remove wheels, the tip of the Philips P1 screw driver can be dipped in automotive valve grinding compound to get a good grip on the screw head.



An automotive battery terminal puller can be used to extract the wheels in order to avoid certain damage to the gear box assemblies.

Shown below is a replacement wheel being put on the axle.


The Aristo couplers and centering springs are to be removed.



Before mounting the Datum Precision Coupler box assembly, tuck under the MU cables if they are not to be used.



Mounting the Coupler box assembly:

Shown below is the example SP RDC1 Datum Precision Coupler Box Assembly mounting:
 


Note that spacer washer and shim thickness may vary from one end to the other end of a car and from car to car from what is exemplified above.

Shown below is the Datum Precision Coupler box assembly mounted on the RDC pedestal with (in this example unused) MU cable tucked under it.



Shown below is the coupler alignment with the Kadee 980 gauge that was obtained using spacer washers and shims.



RDC Operation:

Since I only have one RDC car, the next best thing I could use to evaluate proximity to another unit is to couple an Aristo Dash-9 (plow end) to it and try it on some tracks. Shown below is the RDC and Dash-9 on an 8 foot diameter curve track.



As shown below, the RDC and Dash-9 are very close on the 8 foot diameter curve track, but do not touch.



Shown below, the RDC and Dash-9 are on two Train Li brand R7 turnouts separated with a 6 inch track section. This arrangement constitutes an "S" bend.


The overhead view below shows adequate clearance, and coupler action did not suffer.


Shown below are a couple of pictures with RDC coupled to an AML brand box car equipped with Kadee 830 centerset couplers.


The overhead view below shows plenty of clearance.


Shown below is the RDC as the trailing unit pulling a 61 car test train on the under house layout 10 foot diameter, 270 degree loop back. Other locos coupled to the RDC include the RS-3, and 3 GP40s (out of view). Though this lash up is not prototypical (except maybe for emulating a "dead in tow" RDC) it is a worthy operational test to see how the RDC coupler action performs.


Shown below is an overhead view of the Rock Island RS-3 coupled to the Southern Pacific RDC1.

Shown below is an inside view of the RDC coupled to the RS-3.

Shown below is an outside view of the RDC coupled to the RS-3.

Shown below is an inside view of the RDC1 coupled to the first car of the 61 car train.
The car is a USAT 4 bay cylindrical hopper.


The RDC1 coupled to the 61 car train being assisted with an RS3 and 3 GP40s performed without incident pulling the train. (All locos and the RDC are equipped with Datum Precision Coupler box assemblies having Kadee 901 centerset couplers.)  There were no coupler pull-aparts or separations of any kind.  Due to the length of the RDC with resultant belly overhang, it did "kiss" one of the Aristo Wide Radius turnout switch stand lanterns; however, this is not relevant to its operation on the track. (The switch stand can be repositioned, or its lantern removed.)

The Aristo EMD E8 / E9 Passenger Loco Application - Appendix D 

Topics described include the following:

The EMD E8 / E9 Passenger Loco Application
Comparison Of Aristo Locos
The  Datum Precision / Kadee combination with realism performs well
Possible E8 / E9 Datum Precision Coupler Box Configuration Choices
E8 / E9 Applications List -
Support Plate Purpose
Support Plate Types - Detail & Drawings
Coupler Pin Shapes Illustration
Kadee Coupler Pin R & R
Installation of Plates and DP Coupler Assemblies
Operation on Under House Layout - E9s having  freight pilots
Operation on Under House Layout - E8s having  passenger pilots
Selected Videos
Summary


The Aristo EMD E8 / E9 Passenger Loco Application

The locos in this application have Datum Precision (DP) made CNC machined aluminum coupler boxes fitted with Kadee couplers from Kadee no. 789 kits or the newer generation, AAR "E" types,  from Kadee no. 907 kits. The no. 907 kit includes the Kadee no. 901 separately sold couplers. Both of these coupler types are "centerset" - meaning there is no up or down offset of the coupler head and knuckle with respect to their shank.

The example locos used include a pair of Southern Pacific (SP) E9s equipped with DP boxes having couplers obtained from the traditional  Kadee 789 kit and a  pair of Union Pacific (UP) E8s equipped with DP boxes having the newer 901 couplers. Both  traditional and newer couplers will work OK in either of the loco types. I chose to try both type couplers to establish the universality of the application.

The Aristo E units to be described  with Datum Precision Coupler boxes fitted with Kadee centerset couplers include locos having so called "freight pilots" and "passenger pilots"- whereby, the passenger pilot on the lower part of the front of the loco protrudes outward more so than the freight pilot version.

Comparison Of Aristo Locos

First, a comparison of locos equipped with factory Aristo knuckle couplers is shown below.

The Dash-9, having been retrofitted with Datum Precision boxes with Kadees, was previously discussed, but it is included in the picture to show relative size comparison.

Shown below is an under side view of example Aristo Southern Pacific (SP) E9 having "freight pilot" in the foreground and Union Pacific (UP) E8 having "passenger pilot" in the background. Both units here are retrofitted with Datum Precision metal coupler boxes having Kadee centerset type couplers.

The picture below shows the UP unit on the top, SP unit on the bottom.


To further contrast Kadees to Aristo factory knuckle couplers can be seen in the following pictures:



Looking at the above and below pictures, note the drastic difference from the Aristo toy like separation between the noses and tails of the E units when coupled together.



The  Datum Precision / Kadee combination with realism performs well

The more difficult arrangement of locos is to couple them nose to nose on curve track.

Shown below is the SP E9 freight pilot loco fitted with the more recessed DP / Kadee coupler configuration coupled  to an RDC-1.



Likewise, shown below is the UP passenger pilot loco fitted with a more projected DP/ Kadee coupler configuration to the same RDC-1.



Shown below are various coupled configurations of the E units equipped with Datum Precision boxes having Kadee centerset couplers.



Shown below are relative views with measurements of both units coupled back to back.
Note that passenger pilot and freight pilot version locos are the same for the rear of the units.



Possible E8 / E9 Datum Precision Coupler Box Configuration Choices

There are several possible loco coupler mounting configurations to chose from.  These include the freight pilot loco with and without front recessed coupler and the passenger pilot loco with and without front recessed coupler. The rear of both type locos uses the same coupler configuration.

Datum Precision Coupler boxes were initially developed for installation on the Aristo GP40 and SD45s. They were intentionally made with an extended shank for (the then future) applications that may make use of an additional mounting hole. Accordingly, there are some E8 / E9 configuration applications that make use of an additional hole located just aft of the standard hole.
Shown below is the Datum Precision coupler box with the added mounting hole to the right of the standard hole. The additional hole is to be centered with and located 0.235 inches from the standard hole.


Shown below are example Passenger Pilot configurations



E8 / E9 Applications List -
Based on Support Plates,  Coupler Box Mounting Hole Location, Coupler Pin Shapes

In order to accommodate the various possible E8 / E9 passenger & freight pilot configuration applications, "support plates" are used when mounting the DP coupler boxes, and, in some cases,  modified Kadee coupler "pin shapes" are required. The pins are those metal items that emulate brake hoses and work with Kadee track magnets for uncoupling purposes.
The following  application diagram references support "plate types" and pin "shape illustrations".  The detail about these will be discussed later.




Support Plate Purpose

Installed Datum Precision coupler box assemblies have a two point anchor system. First, the box is placed over the pivot post where the original Aristo coupler had been removed. This is the primary anchor point. 


Support plates provide the second anchor point that facilitates alignment of installed  coupler box assemblies -  both horizontally (so the boxes don't swing side to side) and vertically (so the coupler is at the proper height from the rail head).

The picture below shows the SP E9 on the left coupled nose to nose with the UP E8 on the right.
The bright metal support plates can be seen above the coupler boxes with the SP unit having a more recessed plate and coupler.


Shown below is the SP E9 underside view with the support plate (type F) intended for the more recessed front pilot coupler configuration. This plate and coupler mounting configuration can, also, be used on the UP E8 front passenger type pilot, but the loco with this type pilot will not be able to coupler nose to nose with another E unit; however, it will work when coupled back to back or to a car.



Included in the picture below are the support plates intended for more outwardly projecting coupler  box assemblies.  Also, shown on the bottom of the picture are the rear support plates and coupler box assemblies.

Support Plate Types - Detail & Drawings

There are 3 types of metal support plates identified as type "F", "FS", and "P". These are described and shown in the picture below. The user can choose to fabricate or obtain laser cut plates for the configuration application that he wishes to use.

Optional: To save time, or preferring not to fabricate these support plates, available are Laser Cut "CamPac" metal plates (shown below) that can be obtained by contacting Colin Camarillo via his website

Shown below are the dimensional drawings of the plates along with coupler trip pin,etc. info.
The user is to fabricate the plates for the configuration application that he wishes to use (previously described).

The coupler pins are better shown photographed later at "Coupler Pin Shapes Illustration".

The following drawing, also, includes the DP additional coupler box hole:



Plate fabrication

Referring to the drawing for dimensions, a plate can be marked (scribed) using a scratch-all, and cut with tools shown in the picture below.


If and when using tin snips, there is a tendency for the metal to curl, particularly for longer cuts.
Make sure the plate is flat after the cuts are made.  A vise with smooth jaws can be used with the plate in it to squeeze it flat. If the jaws are not smooth, put something smooth between them and the plate as a buffer.

Instructions for Adding Hole to Datum Precision Box Shank

Care must be taken when drilling the new hole.  One does not want to mess up on an costly part. Take your time and follow the instructions shown in the below picture.


Coupler Pin Shapes Illustration

The user is to bend the Kadee coupler pins for the configuration application that he wishes to use.
Shown below are pictures of the Kadee coupler pins for a given configuration application (previously described). 

Shown below is an example traditional Kadee coupler comparison of Kadee standard shape and modified (re-bent) pin shape.


It's important when a re-shaped pin is installed in the coupler that it be angled to one side like of the original - shown at bottom of picture.

With a pin is re-shaped, it should be of the same overall vertical distance as the originally shaped pin so that when mounted in the coupler it will have the proper clearance over the Kadee uncoupling track magnet.
 
If the pin were to stick down too far, it risks hitting the magnet and possibly other track work - like re-railer ramps and turnout frogs.

Kadee Coupler Pin R & R

The coupler pins can be removed fairly easily and then bent to shape using strong needle nose Vice Grips and needle nose pliers. Until you get "the hang of it", It may take a little effort to get them into the correct shape - usually along with some installation R&R in the loco.
Shown below, a nail punch is used to first push the pin down within the coupler.

 Pliers can be used to remove the pin and then to re-install the pin after being re-bent into the desired shape for the given application.

With pliers well gripped on the pin, ensure coupler knuckle is aligned, then twist pin to proper angle and push firmly down.

When all is installed in the loco, the coupler should swing without interference along the pilot, including when nose to nose coupled to the pilot of another loco.






A properly bent pin is also not to interfere with the bottom of a coupled nose to nose E unit - as shown below.



Installation of Plates and DP Coupler Assemblies

There are methods to install coupler assemblies. I chose to prepare the coupler box assemblies using a method that takes advantage of adjustability when the assembly is installed in a loco that is applicable to all except those having a recessed coupler.

Shown below is an assortment of screw choices used in the process of mounting the DP coupler boxes.


The following  pictures serve to describe the coupler box preparation and installation process:



The UP passenger pilot version is shown in the above and below pictures.

Important Note:
When the DP coupler box assembly is installed and fastened down with the mounting screw on in the loco's pivot post, the mounted assembly should be predisposed so that the coupler end wants to force toward the support plate. If it does not, investigate why and correct. For example, if the nylon spacer washer placed over the loco's pivot post (under coupler box shank) is not seated flat, this will case such a problem. This condition is more likely for applications using the box's standard (front) mounting hole where the washer must be cut like a "D".


The rear installation method and plate is the same for both freight and passenger pilot type locos.

The pictures to follow show the freight pilot SP E9 loco example.

Note: For the freight pilot recessed coupler box installation the screw for the lid is installed after the box is mounted.  This is because the screw is too long for insertion with the box through the front opening space of the loco.

The picture below shows the adjustment for obtaining proper coupler height to rail head. It's the same for both freight and passenger pilot type locos.


Important Note:
Because of Aristo E8 / E9 build tolerances, the nylon spacer washer placed over the front or rear pivot post (under coupler box shank) may not be optimal at 0.032 inch thick as indicated in some pictures. Accordingly (after adjusting the coupler to rail head height to conform the Kadee 880 / 980 gauge) if the coupler box assembly appears to have a notable downward tilt toward the track, then the spacer washer should be thicker. Conversely, if the coupler box assembly appears to have a notable upward tilt, the spacer washer should be thinner.  Readjust the coupler height if changing the spacer washer.

The picture below shows part numbers for the various washers.


The following two pictures are of the SP E9 freight pilot loco having the recessed DP coupler box assemblies installed:

Shown below is the loco with the Kadee 789 type coupler having proper alignment with the Kadee 880 gauge.

The picture below is to illustrate that the newer Kadee type 901 AAR "E" type coupler, also, works in the freight pilot and aligns with the Kadee 980 gauge.


An alternative adjustable coupler height method

Shown below is an alternative method to using the spring to hold the coupler box lid, etc. for adjustability, but it is not as convenient.



Operation on Under House Layout - E9s having  freight pilots

A pair of freight pilot type SP E9s coupled back to back (assisted by a GP40) - all with Datum Precision Coupler boxes and Kadee centerset couplers - is shown below pulling a 61 car test train traversing the 270 degree, 10 foot diameter loop back.



Shown below is the trailing Aristo SP E9 having the recessed mounted coupler box  assembly coupled to the first car of the train (AML brand stock car).

The E9 Datum Precision coupler box is fitted with a traditional centerset coupler from the Kadee 789 kit whilst the stock car is fitted with the newer AAR "E" centerset Kadee 900 coupler. Both traditional and newer coupler types work equally well.


Shown below are the two SP E9s coupled back to back.

The flexible diaphragms do touch at the outer edges.

 The adjustable coupler boxes and "P" type support plates can be seen below.

Shown below is the in side curve view of the E9s coupled together on the loop back.
 

Shown below, the E9 with recessed coupler assembly is coupled to the GP40.

The custom "shape B" re-bent Kadee coupler pin can be seen on the E9. The bent pin allows for free movement of the coupler without interfering with the pilot of the loco; yet the coupler will still uncouple OK as intended using the Kadee track magnet.



Operation on Under House Layout - E8s having  passenger pilots

A pair of passenger pilot type UP E8s coupled back to back (assisted by a GP40) - all with Datum Precision Coupler boxes and Kadee centerset couplers - is shown below pulling the same 61 car test train traversing the 270 degree, 10 foot diameter loop back.



Shown below is the trailing Aristo UP E8 having the recessed mounted coupler box  assembly coupled to the first car of the train (AML brand stock car).

The E8 Datum Precision coupler box is fitted with the newer Kadee 901 AAR "E" type centerset coupler, and the stock car is fitted with the newer Kadee 900 AAR "E" centerset  coupler. Both traditional and newer coupler types work equally well.

The outside view is shown above, and the inside view is shown below.


Shown below are the two UP E8s coupled back to back.

The flexible diaphragms do touch at the outer edges. Shown below is the in side curve view of the E8s coupled together on the loop back.

The adjustable coupler boxes and "P" type support plates can be seen below.


Shown below, the E8 with the projected coupler assembly is coupled to the GP40.

The custom "shape D" re-bent Kadee coupler pin can be seen on the E8. The bent pin allows for free movement of the coupler without interfering with the pilot of the loco; yet the coupler will still uncouple OK as intended using the Kadee track magnet.



Selected Videos

For those interested in viewing videos, I made a number of them during the development process that I sent to Greg E. Though some are not of very good quality (jitter & and poor lighting) he decided to put all of them on his YouTube site. You can search for all of them there, but the examples I believe that may interest most folks are indicated below.

Video title below (4 to 5 minutes time)
"Aristo E8/E9  Passenger Pilot Datum Precision Coupler Box Mount Support Plates, Part F"

END

-Ted