Red Caboose GP9 Aluminum Frame

GP9 aluminum frame is designed specifically to replace the plastic frame delivered with Red Caboose GP9 locomotives.

Machined from 6061-T61 aluminum alloy as a drop-in fit, no modification is needed to the locomotive shell. Machined in prototype underframe detail (see below). Pre-drilled for speaker wiring under the fuel tank. Pre-drilled accessory tray post holes. The GP9 aluminum frame also replaces the flat brass frame sold by others.

Unlike the flat brass frame counterpart sold by some, the FineScale aluminum frame features machined relief pockets on the underside of the frame.

Why go to the extra effort?

The bolsters included with the original GP9 were designed to mount on the top side of the frame. The relief pockets I have machined into the frame allow space for the locomotive trucks to rotate without rubbing the frame. As a result, the trucks sit lower on the frame giving the locomotive a more prototypical stance.

Red Caboose GP9 metal frame with bolster and fuel tank added
With bolsters and fuel tank added

In addition to the relief pockets for the trucks, I have added relief pockets along the sides of the frame. These side frame reliefs let the frame tuck under the locomotive shell and create the side profile of the steel beam that can be seen in the section drawing of a prototype GP9 underframe.

Prototype GP9 Frame Detail
Section detail – GP9

Some argue that the brass frame is a better solution because it adds additional weight. In reality, the brass frame raises the profile of the locomotive, and to me, that negates any benefit of additional weight gain. Add in the absorbent cost of quality brass and aluminum becomes a clear winner.

If you need the extra weight, stick-on lead weight can be added to my frame in any configuration needed to fit the many types of DCC decoder installations, battery onboard installations, and sound installations.

This project started when I considered building my first O-scale layout. I wanted a Proto 48 switching layout that was super detailed. After inquiring online about highly detailed locomotives the Red Caboose GP9 kept coming up in the conversation. I decided to purchase one in the hopes of having a finely crafted GP9 that had an incredible low-speed performance.

To my surprise, the performance of my first O-scale locomotive was dismal! A far cry from the HO scale locomotives I enjoyed so much. The poor performance started me on a quest to improve this fine locomotive. I never intended on selling upgraded parts but as the word spread the demand grew. The GP9 aluminum frame was my first product and is still popular to this day.

GP9 metal frame upgrade kit is intended to be used in conjunction with the P&D hobbies re-power kit #PDP2201K. This metal frame will work with both the plastic and cast brass truck conversion kits offered at P&D hobbies.

Ready to purchase… jump over to the online store.