Changing Kato GP35 Trucks to AAR Type B

[dti406]

Has anybody changed the Kato GP35 Trucks to AAR Type B?

Would the RS2 trucks be a direct change out? Or would I have to modify the Athearn Trucks to fit.

Thanks

Rick Jesionowski

[Deleted]

I have a Kato GP35 and an Atlas C420 frame, the trucks look like a direct swap out so when I get back home tomorrow I can try swap them, see if I can come up with a solution for you?

[santafemikie]

Hi Rick,

Looking at the Kato picture, it should drop right in after you cut off the contacts for the frame mounted strips of the RS-2. You will then need to "hard wire" the contacts to the lighting board or your DCC receiver. When you order the trucks, they will sell you the wires also if you like. The mounting holes on the Kato trucks are at a different height so they will NOT interchange with either the Atlas or the Athearn trucks without some serious machining and fabrication in the bolster areas.

Cheers, Mike

[e86900]

Rick,
I use AAR type B sideframes from Bowser. For the most part, they are a direct fit on the Kato GP35 truck. I had to do a tiny bit of filing on the locking slots on the mounting pins. The tabs on the gearbox cover that lock the sideframes in place were just a little to wide to fit in the locking slots. The bearing plates from the Kato trucks fit the AAR sideframes perfectly. Bear in mind that the prototype AAR type B truck is longer that a Blomberg truck, and Bowser's sideframe has been shortened to fit the Blomberg truck. I find that it still looks good, and if you add sanding lines, it's not noticable. My whole GP35 fleet has this conversion. The Bowser part number for the AAR type B truck is 691-176@ $1.38x4. The brake cylinders are seperate pieces, part number 691-191@ .35x16 to do one engine

[dtinut]

Rick,

I have done this, they do fit, but a couple things must be done.
The RS-2 trucks have a gear bump that sticks up, and will make contact with the frame.
I was able to mill the cavity required into the frame on both ends of the frame inboard of the truck bolster. This could be accomplished with a dremel also.
The bolster thickness (inside the shell) needs about .060" added to it because the GP frame isn't as think as the RS2 frame was, so the trucks will have a lot of slop when lifted, and they may come of the truck pins without the added shim to make the clips fit better. The bowser/stewart sideframe will fit the Kato trucks, but are shorter because they are made to fit blomberg trucks, which are a scale 4" shorter than AAR-B's.
Also - you need to cut a scale 7" off each end of the fuel tank, as GP35's with the AAR-B's had a smaller tank to clear the brake levers on the trucks.

This is a bit of work without a mill, which makes it an easy job to do this stuff. But a hack saw will accomplish this part as well.

I decided after building my first Ann Arbor GP35 with these changes, to find P2K GP30's with the AAR-B trucks, and use the drive under the Kato shell. A little work to make it fit, but not as much, and the fuel tank and trucks are a little nicer on the P2K than the Kato versions IMHO... I sold the P2K shells for decent change afterwards, which help offset the cost, and I have Kato drives available for use under P2K GP30's.

[dti406]

Thanks to all that have responded to this question. I have a lot to think about in order to make my AA unit. I finally managed to nab a Phase 1b unit, but I know I needed the AAR trucks to make it correct.

Rick J

[dtinut]

Rick, Here is a image showing the work done to make those RS-2 trucks fit



Finished model