Dash 9

(remember: links to sub-pages at the bottom of this page)

click to jump to the bottom


The longest diesel loco made in G scale. Often purchased for that reason, much to the chagrin of people who don't have broad curves. Nicely made, same power trucks as the other Aristo 3 axle diesels.

In 2012, with very little fanfare Aristo revised the wheel contours on their diesels. The first loco to see this change is the Dash 9. I contacted Scott Polk about getting a set of wheels to try and evaluate, but since the only new ones were on the new Dash 9's he sent me the entire loco for evaluation. (unfortunately the company went under before these were implemented across all diesels). I'm not positive if they made them to the last run of the SD45's, which were high nose.

At the same time,I have been evaluating the beta versions of the new QSI Titan plug and play decoder, so you will see references to it here also.

The Aristo socket is there, you need to remove the "lid" which has the horns and the smoke stack. It just pulls up. Be careful when replacing, the connector for the smoke unit is very  close and can interfere with the tab holding the lid in, it seems you could even damage the connector if it's not properly installed.

Pull out the 6 screws on the trim panel that holds the switches and smoke unit (don't remove the smoke unit screws it stays attached to the panel).

When installing a decoder, the "tightest" wire will be the one to the regulator screwed to the metal chassis. If you ever modify the loco, attach it to the other side of the frame.


Prototype info:....deck ..walk way ..70"
....plow clearance.  ..4"
....fuel tank clearance.  ....8"

Bachmann re-issue

2022 or so, Bachmann announced they would re-issue this, arrived mid year 2023, see link at end of this page

New wheel contours February 2012

As noted above, in 2012 Aristo released a new wheel contour, and the only 3 axle locomotive shipped was the dash 9.

(note these measurements were done on 2 different Dash 9's, one owned by RJ DeBerg, and one loaned to me for evaluation by Scott Polk.

Please remember that the measurements for the flange depth are calculated and are relative to the wheel diameter at the flange. In reality, the wheels will normally be riding in the middle of the wheel tread, and so the flange depth might be more, but this measurement (middle of tread) is very hard to make repeatable.

Measurements of original Dash 9 wheels:

Overall diameter (including flange): 1.615
Tread diameter close to flange: 1.375-1.378
Difference (should be flange times 2):  0.24
Calculated flange depth: 0.12"
Flange thickness at base: 0.077 - 0.079

Background / comparision data, Limited run of Aristo SS wheels:

Overall diameter (including flange): 1.533"
Tread diameter close to flange:1.379"
Difference (should be flange times 2): 0.154"
Calculated flange depth: 0.077
Flange thickness at base:

Background / comparision data, Ted Doskaris' custom SS wheels:

Overall diameter (including flange):1.558
Tread diameter close to flange:1.393
Difference (should be flange times 2): 0.165
Calculated flange depth is 0.0825
Flange thickness at base: 0.065

Measurement of new Dash 9 wheels - RJ:

Overall diameter (including flange):1.573
Tread diameter close to flange:1.380
Difference (should be flange times 2): 0.193
Calculated flange depth: 0.0965
Flange thickness at base: 0.063

Measurement of new Dash 9 wheels - Greg:

Overall diameter (including flange):1.571
Tread diameter close to flange:1.379
Difference (should be flange times 2): 0.192
Calculated flange depth is:0.096
Flange thickness at base is 0.066

Wheel back to back for front truck starting at front leading wheel set. - RJ

1.580 L
1.586 M
1.583 T
Rear truck wheel set closest to fuel tank
1.566 L
1.593 M
1.581 T

Wheel back to back for front truck starting at front leading wheel set. - Greg

1.575 L
1.583 M
1.571 T
Rear truck wheel set closest to fuel tank
1.573 L
1.569 M
1.570 T

Conclusions and observations:

Aristo is to be congratulated for making what I believe are the first Large Scale wheels that meet the NMRA standard.

Candidly, it's not often the NMRA gets things "right" for large scale, but this time, with the help of real hobbiests, they did a good job.

The improvements needed were, back to back spacing, flange thickness, wheel gauge, and flange depth.

Improvement on back to back:

The NMRA target is 1.575". The Aristo wheels varied from 0.018 over to 0.009 under. This is a pretty sloppy tolerance, but almost all wheelsets were within NMRA tolerances. The design of the tapered axle tip and tapered hole in the wheel probably makes it impossible to get more consistency. The bottom line, is that it meets the standard. Possibly swapping wheels around a bit could get things closer.

Improvement on wheel gauge:

The wheel gauge is actually less important than back to back. Basically if your flange thickness is within NMRA tolerances, and your back to back gauge is also, then your actual wheel gauge will be ok.

Previously, the flange thickness was 0.078", the new flange thickness is 0.063 to 0.066. This is quite a change. The NMRA standard for flange thickness is 0.059" + 0.002" -0.018, the G1MRA is 0.060" + 0.0" -0.020.

As you can see, this is a radical change and a huge improvement. Basically with the previous excessive flange width, it was impossible to have both back to back gauge and wheel gauge correct, since the flange was way too thick.

This is a great step by Aristo, since they risked many people complaining that something was wrong. Clearly some trackwork may now cause problems since the wheel gauge may effectively been changed, but if people make sure their trackwork meets NMRA standards their track.



Let me restate the situation about these new wheel standards: If your trackwork meets NMRA standards, not only will you have not problems, but your locomotives will run more reliabily with these new wheelsets and standards.

Other than the somwhat sloppy variation in gauge, these wheels seem just about the best that can be made for these locomotives.

Remember that since the Aristo 3 axle truck is not sprung, vertical transitions can and will lift either the leading or trailing axle. Any further reduction in flange depth could easily cause more running problems that would not justify the improvement in appearance of the wheels.



At first, the Dash 9's shipped with 3 weights, one installed and 2 more. They were lead and 2 pounds:

Later, all Aristo lead weights were replaced with zinc, which is about half the weight, and no longer shipped in the carton.



Unfortunately, in early 2012, the lead weights and the zinc weights are gone, replaced by a stack of steel plates:


Here is an excellent page by Paul Norton that shows how to disassemble the loco, and also fitting of a battery: 


  1. Remove the 4 screws that hold on the fuel tank.
  2. There are now 14 more screws, remove the 4 screws that are under the center of the fuel tank.
  3. Remove 2 at the back end, not the outer 2 that hold the rear deck, but the inner 2 that hold on the shell.
  4. Remove 2 at the front (cab end), again not the 2 that hold the deck, but the 2 in the extreme corners that hold the shell
  5. 2 more under the inner axle of the rear truck
  6. 4 more under the front truck, 2 on the engineers side are 1/2 inch apart, the 2 on the firemans side are about 2 inches apart.

remove grab irons on front nose.... also be careful to open a bit and unplug the front headlight wire, it's short.



Click the links below to go "deeper" into details on the Aristo Dash 9

  Dash 9 QSI Install   Early Dash 9 Issues   Bachmann re-issue                                                 
Weather Underground PWS KCACARLS78