Motor shims on Lionel Conventional Classic Geeps

Manufacturers generally do not include pieces that are not needed. They build things as cheaply as possible. If the shim tilts the motor, it may be there to put some play into the meshing of the gears. Maybe that was done to save a batch of gear boxes that were machined incorrectly. Chinese machining does not seem as precise as we were used to with postwar American made products.

Most likely they were used to get the proper mesh of the gears. Since the gears are now worn in, the shims may not be necessary.

Rod Miller

I performed a quick test where I ran one Geep with the shim, and then again without it. Although somewhat subjective, I thought the loco was a bit more quiet and smoother without the shim. I saw no difference between the two cases with respect to voltage or current. So I'm leaving the shims out and saving them if needed later.

Note that using the shim pushes the worm gear closer to the center gear on the shaft in the basic power truck thus giving a tighter gear mesh. The center gear on the truck drive shaft that mates with the worm gear is made of bronze so it will take a long, long time before those gears show any wear. The outer spur drive gear and idler gears are made of a plastic material and will probably wear out long before the inner bronze gear or steel worm gear!

The motors and basic power trucks on the CC Geeps and F3's are probably the same. I don't know if shims were used in the CC F3's so I 'll have to check them out whenever I get a chance.

Ken

Digging into the memory bank...

Wasn't there a gear mesh issue with some of the CC locos a few years back? Thinking of the Alcos, especially the MStL engine that came with the Orbiter Set. Seem to recall several here installing their own shims to reduce a grinding/rough running situation.

Hotbox posted:

I performed a quick test where I ran one Geep with the shim, and then again without it. Although somewhat subjective, I thought the loco was a bit more quiet and smoother without the shim. I saw no difference between the two cases with respect to voltage or current. So I'm leaving the shims out and saving them if needed later.

Note that using the shim pushes the worm gear closer to the center gear on the shaft in the basic power truck thus giving a tighter gear mesh. The center gear on the truck drive shaft that mates with the worm gear is made of bronze so it will take a long, long time before those gears show any wear. The outer spur drive gear and idler gears are made of a plastic material and will probably wear out long before the inner bronze gear or steel worm gear!

The motors and basic power trucks on the CC Geeps and F3's are probably the same. I don't know if shims were used in the CC F3's so I 'll have to check them out whenever I get a chance.

Ken

If you aren't noticing any difference in operation with or without the shims, you should leave them in place. 

The shims provide for a higher percent of full mesh between the worm gear and worm wheel. You want the mesh to be as full as possible without binding. Postwar service manual instructions stated this point. 

If you remove the shims and reduce your percentage of full gear mesh, it places more stress and wear on a smaller contact area. You may not notice the increased speed of wear, but it is occurring. 

In the course of my repair work I have seen many modern era locos chew up a brass worm wheel long before a failure in the plastic pinion or spur gears ever occurs. 

johnstrains posted:

Digging into the memory bank...

Wasn't there a gear mesh issue with some of the CC locos a few years back? Thinking of the Alcos, especially the MStL engine that came with the Orbiter Set. Seem to recall several here installing their own shims to reduce a grinding/rough running situation.

This particular Alco engine needs a lot of help out of the box to run smooth. On mine, I drilled out and installed a new brush plate bearing, shimmed the brush plate, ground a few mills of the armature laminations and put a ball bearing at the bottom of the armature. Then I had to glue on the little tabs on the truck side frames that prevent the frame from slipping from side to side. They missed that detail among many others on their new tooling.