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South Jersey S Scale Modelers

PRR GP7 8553


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I bought this Sunset GP7 many years ago with the intention of removing the roof top air tanks and making it a freight unit. This was made in Japan in 1984 as very early S Scale brass.


My procrastination of starting this loco lead to the discovery of PRR 8553, which ran with some frequency on the PRSL as a passenger unit. The PRR was ordering diesel locomotives purpose built with the equipment options almost to the point of pulling a particular train. So, this all fits my PRSL, the torpedo tanks stay, and I added the PRR antennas along with some other modifications and details.


Reworking The Drive


The drive was this horrid straight shaft running the length of the interior with cogged pulleys and rubber belts down to cogged pulleys on the trucks. The rubber belts likely took a set in sitting making for an awful runner. I hated the rubber belt drive so much I did not even pause to take any photos of it. I stripped out the parts in a frenzy and SOLD them!


Photos by Bill Winans and Rich Gajnak

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My delay starting this project worked well. The solution of using some extraneous Overland F Unit gearboxes came to me and was a surprisingly easy fix.


My first round of working on this project was in August 2013. Below are some photos of the drive mock up. The lack of good driveshafts likely killed progress for over 2 years. The later efforts are usually different and better than I could have done previously. I have since moved away from wanting to use flywheels, now depending more on the decoder programming for momentum. And I did not have 3D printing capabilities in 2013 to come to the rescue in solving the driveshaft problems.


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December 2015

Progress on 8553 is reignited because my friend Bob Frascella posted a photo of his completed 8551.

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3D Printing

These are the universal joints I designed and printed. There were various versions but I settled on using square brass tube as the drive shaft because I needed them to be telescopic.  I probably could have bought universal joints but making what I need is well apart of the challenge and the FUN of it all for me. I got pretty lucky in the design of the ball and socket. It mostly worked the first time with only some minor tweaking. The 3D material is very slightly flexible when first printed. That is how I can snap the socket onto the ball. But it gets harder and brittle in about a week if exposed to light. I give it a liberal shot of oil, and think (HOPE) it will be just as durable as plastic.


Universal Joints

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Motor Mount

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More work on the drive

The truck bolster screw originally attached right to the floor. Since the U Joint hubs are now permanently attached to the gear tower shafts accessing the truck screw would be difficult. I made these spanner bars to be able to access 2 screws on either side of the driveshafts.

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All Wheel Pickup

I made my usual all wheel pick up system. I cut grooves in the back of the wheels for the wiper wires to ride in. I use phosphor bronze wire only. All wheel pickup is a LOT of work but it greatly improves performance.

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The model as built had a reasonable draft gear casting I hoped to use. But the opening and coupler pad was originally designed for a Kadee #5 where I use Kadee #802 for S Scale. I designed a custom box where there really is no coupler box, at least in the draft gear. The 802 fits and centers well. The opening is just a little wider than I would prefer, but does not bother me enough to change it.

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This is the layout of the Tsunami decoder and speaker I chose. The decoder is not visible in the roof of the cab. The speaker is available from RailMaster. http://www.railmasterhobbies.com/Speakers.htm I use lots of Miniatronics plugs to make working on it easy. There is a 4 wire plug to separate the shell from the drive for “power up – motor down” since the decoder is attached to the roof. All the electronics and lights stay in the roof of the shell. This is the general layout I use most of the time. I am using all LEDs from now on.

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Some test running before disassembly



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Fuel Tank and Train Control Box

The fuel tank was too long so I shortened it almost 1 inch. For the first time I am using 3D printed parts without getting them cast in brass on a brass model. This is the train control box.

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Rooftop “Torpedo” Air Tanks

I decided the original Sunset torpedo air tanks were too wrong to keep. Among other things they are too short. Bill’s Train Shop http://www.btsrr.com sells a tank kit that is just perfect including the piping. The old tanks had to go to use the BTS kit. The before photo is at left. They are various stages of laying out the new holes, filling on the old holes, tapping the new tanks and tank replacement completed. This improvement is 1 of the most important changes I made.


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PRR Antennas & Ultrasonic Cleaning

There is great angst and procrastination in adding antennas to a PRR loco. Getting the stanchions in the correct place is important. I am obsessed with making them in a straight line. That requires good measuring and layout. I have never seen real PRR stanchion placement drawings. Finding overhead photos is difficult. In this case I started with the stanchions on either end of the air tanks and used them to set the shorter stanchions on the tanks. I could have never soldered the stanchions to the air tanks without my resistance soldering unit. I worked my way out in both directions until I was done. The shorter cab stanchion was the last installed. Note that the steam generator exhaust stack has been moved. It took all this time to notice it was on the wrong side of the short hood!


I got very lucky and won a photo on eBay of the Trainphone receiver coil of 8553! I am sure it is an EMD photo. So I had a good reference to make my receiver coil. Soldering the coil to the roof was a challenge without it falling back into 3 pieces. Again, this work was not possible without my resistance soldering unit.


I used solder flux for a lot of the detail work. This concerned me that there was some flux left in areas I could not reach with the blast gun that could corrode later and push the paint off. So I used my ultrasonic cleaner machine for the first time. There are brass ultrasonic cleaning solutions that I was scared to use, so I used water and some Dawn dish soap. I was skeptical that it was doing anything, but after a few minutes the water was not as clear and there was some debris in the bottom of the tank.


That body modifications are done at this point. Onward to completing the new handrails.


 I still blasted the body just before paint.


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I must not have taken any in progress photos of making the handrails. They are very fragile.

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2017 Reboot


Added 5-28-17

Procrastination hit again, that put 8553 back in the box for another 18 months. Among other things in that time, I made a Reading Trainmaster, Reading SW1, and completed my 2 PRR L1 and 2 PRR I1. Completing the 4 steam locos was a major accomplishment.


Again, this has taken a turn to become a different and better model. I am now frequently using WOW4 decoders with a Keep Alive capacitor bank. The original Tsunamis are going away. I also switched to the Overland HO diesel driveshafts. The 3D printed U Joints I designed were fun to make, but very brittle. I had my doubts even in back 2015 that they would durable enough to last as a wear part. The Overland driveshafts are a little short so I used heat shrink tubing to help keep them concentric. I used a barbeque lighter to shrink the tube with the motor running! I skimmed the heat shrink tubing with a Dremel drum sander to try and balance that rotation a little more. It helped a bit.


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Since I changed a few things in the drive I threw it back together for another test run. It has never run before with the detailing done. I am pretty happy with the results. I like flame throwing headlights. These LEDs are awesome. I found a few distracting light leaks that have to be fixed before painting.


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Completed 6-10-17


The fuel tank is completely open without a gear tower, so it was perfect for adding weight. I saw a mention of “Liquid Gravity”, instead of my idea to pour molten lead in risking complete disassembly. It was a literal 2 minutes. It worked very well. I gave a liberal dose of ACC. An hour later is it a rock. I gained almost 6 ounces.


It worked well, but was a little boring instead of the molten lead. Maybe sometimes boring and safe are good! I still think it is a steel shot blast media, not anything developed for model railroad use.


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Updated 2-25-18

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