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PVC Motor Retainer

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DynaSoar

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I hacked myself an alternative to the 29mm Universal Engine Retainer at http://silent1.home.netcom.com/umrs.htm

I took a 1 1/4" PVC bushing and cut off the threaded portion. (Could be any male threaded 1 1/4" PVC). I cut 3/4" of 29mm motor tube, slit it down the side, and glued it to the inside of the threaded part with CyA. This made a good fit with the existing 29mm tube (the PVC part being a bit loose). I squirted epoxy down into the space between the bird's BT and the engine tube, and slid the threaded part down over the motor tube until the lower few threads were in the epoxy. This displaced the epoxy a bit and pushed it up so it filled up the BT/MT gap completely.

Then I got a 1 1/4" insulated PVC bushing (found in the electrical conduit components, rather than the plumbing parts). It's much smaller and lighter than the cap used in the article. It's also made with ribs on the side since it's designed for easy tightening and loosening, so it looks good and it's easy to turn on/off. The hole in it is the same size as the motor tube, so I got a 1" E clip (like a snap ring, but with three ears/tabs on it) and put it in the bushing cap. It fit down inside the cap perectly, and has plenty of space for the motor nozzle to protrude through.

The bushing with E clip inside then screws down onto the tube, holding the motor in place. The outer diameter of the busing is 1.75", so the bird needs to be that size or larger, or it will stick out. In this case, the bird was an NCR Renegade-X, which is 1.75" diameter, so it ended up a perfect fit.

Since I bought a part for the threads that was more than I needed, and could only find the E clips in a package of 2, I ended up spending about $3.
 

DynaSoar

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Here, finally, is a picture of the retainer, open (top right) and closed (bottom right) on an NCR Renegade-X (left). Turnaround time (opening, removing engine, inserting new engine, closing) is under 30 seconds.
 
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